Day14 - elm后端MyBatis版

## 一、设计数据库

#### 1、数据库结构

| No | 表名称   | 中文名   | 说明                             |
| -- | -------- | -------- | -------------------------------- |
| 1  | business | 商家表   | 存储所有商家信息                 |
| 2  | food     | 食品表   | 存储每个商家所拥有的所有食品信息 |
| 3  | admin    | 管理员表 | 存储管理员信息                   |

#### 2、表结构

约束类型标识：

- PK：primary key 主键
- FK：foreign key 外键
- NN：not null 非空
- UQ：unique 唯一索引
- AI：auto increment 自增

##### business（商家表）

| No | 字段名        | 数据类型 | size  | 默认値 | 约束       | 说明     |
| -- | ------------- | -------- | ----- | ------ | ---------- | -------- |
| 1  | bid           | int      |       |        | PK、AI、NN | 商家编号 |
| 2  | password      | varchar  | 20    |        | NN         | 密码     |
| 3  | bname         | varchar  | 40    |        | NN         | 商家名称 |
| 4  | address       | varchar  | 50    |        |            | 商家地址 |
| 5  | explain       | varchar  | 100   |        |            | 商家介绍 |
| 6  | starPrice     | decimal  | (5,2) | 0.00   |            | 起送费   |
| 7  | deliveryPrice | decimal  | (5,2) | 0.00   |            | 配送费   |

##### food（食品表）

| No | 字段名  | 数据类型 | size  | 默认値 | 约束       | 说明         |
| -- | ------- | -------- | ----- | ------ | ---------- | ------------ |
| 1  | fid     | int      |       |        | PK、AI、NN | 食品编号     |
| 2  | fname   | varchar  | 30    |        | NN         | 食品名称     |
| 3  | explain | varchar  | 30    |        |            | 食品介绍     |
| 4  | price   | decimal  | (5,2) |        | NN         | 食品价格     |
| 5  | bid     | int      |       |        | FK、NN     | 所属商家编号 |

##### admin（管理员表）

| No | 字段名   | 数据类型 | size | 默认値 | 约束       | 说明       |
| -- | -------- | -------- | ---- | ------ | ---------- | ---------- |
| 1  | aid      | int      |      |        | PK、AI、NN | 管理员编号 |
| 2  | aname    | varchar  | 20   |        | NN、UQ     | 管理员名称 |
| 3  | password | varchar  | 20   |        | NN         | 密码       |

#### 3、SQL语句

```SQL
CREATE DATABASE IF NOT EXISTS elm CHARSET utf8;
USE elm;
CREATE TABLE IF NOT EXISTS business
(
    bid           INT UNSIGNED PRIMARY KEY AUTO_INCREMENT COMMENT '商家编号',
    password      VARCHAR(20) NOT NULL COMMENT '密码',
    bname         VARCHAR(40) NOT NULL COMMENT '商家名称',
    address       VARCHAR(50) COMMENT '商家地址',
    `explain`     VARCHAR(100) COMMENT '商家介绍',
    startPrice    DECIMAL(5, 2) DEFAULT 0.00 COMMENT '起送费',
    deliveryPrice DECIMAL(5, 2) DEFAULT 0.00 COMMENT '配送费'
);

CREATE TABLE IF NOT EXISTS food
(
    fid       INT UNSIGNED PRIMARY KEY AUTO_INCREMENT COMMENT '食品编号',
    fname     VARCHAR(30)   NOT NULL COMMENT '食品名称',
    `explain` VARCHAR(30) COMMENT '食品介绍',
    price     DECIMAL(5, 2) NOT NULL COMMENT '食品价格',
    bid       INT UNSIGNED  NOT NULL COMMENT '所属商家编号',
    FOREIGN KEY (bid) REFERENCES business (bid)
);

CREATE TABLE IF NOT EXISTS admin
(
    aid      INT UNSIGNED PRIMARY KEY AUTO_INCREMENT COMMENT '管理员编号',
    aname    VARCHAR(20) NOT NULL UNIQUE COMMENT '管理员名称',
    password VARCHAR(20) NOT NULL COMMENT '密码'
);
INSERT INTO admin(aname, `password`)
VALUES ('admin', 'admin');
```

## 二、添加依赖库

这次用到的是`Maven`项目，所以在`pom.xml`文件添加`dependencis`，依赖的库有`jdbc9.4.0`、`mybatis3.5.19`、`log4j1.2.17`

```xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

<groupId>org.example</groupId>
    <artifactId>eml-MyBatis</artifactId>
    <version>1.0-SNAPSHOT</version>

<dependencies>
        
        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <version>9.4.0</version>
        </dependency>
        
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.19</version>
        </dependency>
        
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
    </dependencies>

</project>
```

## 三、添加配置文件

在`rescources`资源目录下创建下面的文件。

#### 1、数据库配置文件

创建`db.properties`

```properties
jdbc.mysql.driver=com.mysql.cj.jdbc.Driver
jdbc.mysql.url=jdbc:mysql://localhost:3306/elm?useUnicode=true&useSSL=false&serverTimezone=Asia/Shanghai&characterEncoding=utf8
jdbc.mysql.username=username
jdbc.mysql.password=password
```

#### 2、日志配置文件

创建`log4j.properties`

```properties
log4j.rootLogger=ERROR, stdout

log4j.logger.org.mybatis.example.BlogMapper=TRACE

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n
```

3、MyBatis配置文件

创建`sqlMapConfig.xml`

```xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>
    
    <properties resource="db.properties"/>
    <settings>
        
        <setting name="lazyLoadingEnabled" value="true"/> 
        <setting name="aggressiveLazyLoading" value="false"/> 
    </settings>
    <typeAliases>
        <package name="com.doooog.mybatis.po"/>
    </typeAliases>
    
    <environments default="development">
        <environment id="development">
            
            <transactionManager type="JDBC"/>
            
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.mysql.driver}"/>
                <property name="url" value="${jdbc.mysql.url}"/>
                <property name="username" value="${jdbc.mysql.username}"/>
                <property name="password" value="${jdbc.mysql.password}"/>
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
        <package name="com.doooog.elmMyBatis.mapper"/>
    </mappers>
</configuration>
```

## 四、创建`model`层

新建`com.doooog.elmmybatis.po`包

#### 1、`Admin.java`类

```java
package com.doooog.elmmybatis.po;

public class Admin {
    private Integer aid;
    private String aname;
    private String password;

public Admin() {
    }

public Admin(Integer aid, String aname, String password) {
        this.aid = aid;
        this.aname = aname;
        this.password = password;
    }

@Override
    public String toString() {
        return "Admin{" +
                "aid=" + aid +
                ", aname='" + aname + '\'' +
                ", password='" + password + '\'' +
                '}';
    }

public boolean isEmpty() {
        return aid == null && (aname == null || aname.isEmpty()) && (password == null || password.isEmpty());
    }

public boolean isUnsafe(boolean withPK) {
        if (!withPK) {
            return isEmpty() || aname == null || aname.isEmpty() || password == null || password.isEmpty();
        } else {
            return isEmpty() || aid == null || aid <= 0 || aname == null || aname.isEmpty() || password == null || password.isEmpty();
        }
    }

public Integer getAid() {
        return aid;
    }

public void setAid(Integer aid) {
        this.aid = aid;
    }

public String getAname() {
        return aname;
    }

public void setAname(String aname) {
        this.aname = aname;
    }

public String getPassword() {
        return password;
    }

public void setPassword(String password) {
        this.password = password;
    }
}
```

#### 2、`Business.java`类

```java
package com.doooog.elmmybatis.po;

import java.util.List;

public class Business {
    private Integer bid;
    private String password;
    private String bname;
    private String address;
    private String explain;
    private Double startPrice;
    private Double deliveryPrice;

private List<Food> foodList;

public Business() {
    }

public Business(Integer bid, String password, String bname, String address, String explain, Double startPrice, Double deliveryPrice) {
        this.bid = bid;
        this.password = password;
        this.bname = bname;
        this.address = address;
        this.explain = explain;
        this.startPrice = startPrice;
        this.deliveryPrice = deliveryPrice;
    }

public Business(Integer bid, String password, String bname, String address, String explain, Double startPrice, Double deliveryPrice, List<Food> foodList) {
        this.bid = bid;
        this.password = password;
        this.bname = bname;
        this.address = address;
        this.explain = explain;
        this.startPrice = startPrice;
        this.deliveryPrice = deliveryPrice;
        this.foodList = foodList;
    }

@Override
    public String toString() {
        return "Business{" +
                "bid=" + bid +
                ", password='" + password + '\'' +
                ", bname='" + bname + '\'' +
                ", address='" + address + '\'' +
                ", explain='" + explain + '\'' +
                ", startPrice=" + startPrice +
                ", deliveryPrice=" + deliveryPrice +
                ", foodList=" + ((foodList != null && !foodList.isEmpty()) ? foodList : "null") +
                '}';
    }

public boolean isEmpty() {
        return bid == null && (bname == null || bname.isEmpty()) && (address == null || address.isEmpty()) && (explain == null || explain.isEmpty()) && startPrice == null && deliveryPrice == null && (foodList == null || foodList.isEmpty());
    }

public boolean isUnsafe(boolean withPK) {
        if (!withPK) {
            return isEmpty() || password == null || password.isEmpty() || bname == null || bname.isEmpty();
        } else {
            return isEmpty() || bid == null || bid <= 0 || password == null || password.isEmpty() || bname == null || bname.isEmpty();
        }
    }

public Business copy() {
        return new Business(bid, password, bname, address, explain, startPrice, deliveryPrice, foodList);
    }

public List<Food> getFoodList() {
        return foodList;
    }

public void setFoodList(List<Food> foodList) {
        this.foodList = foodList;
    }

public Integer getBid() {
        return bid;
    }

public void setBid(Integer bid) {
        this.bid = bid;
    }

public String getPassword() {
        return password;
    }

public void setPassword(String password) {
        this.password = password;
    }

public String getBname() {
        return bname;
    }

public void setBname(String bname) {
        this.bname = bname;
    }

public String getAddress() {
        return address;
    }

public void setAddress(String address) {
        this.address = address;
    }

public String getExplain() {
        return explain;
    }

public void setExplain(String explain) {
        this.explain = explain;
    }

public Double getStartPrice() {
        return startPrice;
    }

public void setStartPrice(Double startPrice) {
        this.startPrice = startPrice;
    }

public Double getDeliveryPrice() {
        return deliveryPrice;
    }

public void setDeliveryPrice(Double deliveryPrice) {
        this.deliveryPrice = deliveryPrice;
    }
}
```

#### 3、`food.java`类

```java
package com.doooog.elmmybatis.po;

public class Food {
    private Integer fid;
    private String fname;
    private String explain;
    private Double price;
    private Integer bid;

private Business business;

public Food() {
    }

public Food(Integer fid, String fname, String explain, Double price, Integer bid) {
        this.fid = fid;
        this.fname = fname;
        this.explain = explain;
        this.price = price;
        this.bid = bid;
    }

public Food(Integer fid, String fname, String explain, Double price, Integer bid, Business business) {
        this.fid = fid;
        this.fname = fname;
        this.explain = explain;
        this.price = price;
        this.bid = bid;
        this.business = business;
    }

@Override
    public String toString() {
        return "Food{" +
                "fid=" + fid +
                ", fname='" + fname + '\'' +
                ", explain='" + explain + '\'' +
                ", price=" + price +
                ", bid=" + bid +
                ", business=" + ((business != null && !business.isEmpty()) ? business : "null") +
                '}';
    }

public boolean isEmpty() {
        return fid == null && (fname == null || fname.isEmpty()) && (explain == null || explain.isEmpty()) && price == null && bid == null && (business == null || business.isEmpty());
    }

public boolean isUnsafe(boolean withPK) {
        if (!withPK) {
            return this.isEmpty() || bid == null || bid <= 0 || fname == null || fname.isEmpty() || price == null || price <= 0;
        } else {
            return this.isEmpty() || fid == null || fid <= 0 || bid == null || bid <= 0 || fname == null || fname.isEmpty() || price == null || price <= 0;
        }
    }

public Integer getFid() {
        return fid;
    }

public void setFid(Integer fid) {
        this.fid = fid;
    }

public String getFname() {
        return fname;
    }

public void setFname(String fname) {
        this.fname = fname;
    }

public String getExplain() {
        return explain;
    }

public void setExplain(String explain) {
        this.explain = explain;
    }

public Double getPrice() {
        return price;
    }

public void setPrice(Double price) {
        this.price = price;
    }

public Integer getBid() {
        return bid;
    }

public void setBid(Integer bid) {
        this.bid = bid;
    }

public Business getBusiness() {
        return business;
    }

public void setBusiness(Business business) {
        this.business = business;
    }
}
```

## 五、创建`util`层

新建`com.doooog.elmmybatis.util`包

#### 1、数据库工具类

```java
package com.doooog.elmmybatis.util;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

public class DBUtil {
    private static final SqlSessionFactory sqlSessionFactory;

static {
        SqlSessionFactory sqlSessionFactory1;
        try {
            // 1、读取Mybatis配置文件
            InputStream input = Resources.getResourceAsStream("SqlMapConfig.xml");
            // 2、通过配置文件信息，创建SqlSessionFactory
            sqlSessionFactory1 = new SqlSessionFactoryBuilder().build(input);
        } catch (IOException e) {
            sqlSessionFactory1 = null;
            System.out.println(e.getMessage());
        }
        sqlSessionFactory = sqlSessionFactory1;
    }

public static SqlSessionFactory getSqlSessionFactory() {
        return sqlSessionFactory;
    }
}
```

#### 2、输入工具类

```java
package com.doooog.elmmybatis.util;

import java.util.InputMismatchException;
import java.util.Scanner;

public class InputUtil {
    private static final Scanner INPUT = new Scanner(System.in);
    public static int menuInputInteger(String msg) {
        int data;
        try {
            data = INPUT.nextInt();
            if (data < -2) throw new InputMismatchException();
        } catch (InputMismatchException e) {
            INPUT.nextLine();
            if (!msg.isEmpty()) {
                System.out.print("输入的类型错误！请重新输入" + msg + ":");
            } else {
                System.out.print("输入的类型错误！请重新输入:");
            }
            data = menuInputInteger(msg);
        }
        return data;
    }
    public static double menuInputDouble(String msg) {
        double data;
        try {
            data = INPUT.nextDouble();
            if (data < 0 && data != -1) throw new InputMismatchException();
        } catch (InputMismatchException e) {
            INPUT.nextLine();
            if (!msg.isEmpty()) {
                System.out.print("输入的类型错误！请重新输入" + msg + ":");
            } else {
                System.out.print("输入的类型错误！请重新输入:");
            }
            data = menuInputDouble(msg);
        }
        return data;
    }

public static String menuInputString(String msg) {
        String data;
        try {
            data = INPUT.next();
        } catch (InputMismatchException e) {
            INPUT.nextLine();
            if (!msg.isEmpty()) {
                System.out.print("输入的类型错误！请重新输入" + msg + ":");
            } else {
                System.out.print("输入的类型错误！请重新输入:");
            }
            data = menuInputString(msg);
        }
        return data;
    }
}
```

#### 3、其他工具类

```java
package com.doooog.elmmybatis.util;

public class CommonUtil {
    public static String copyChar(char c, int num) {
        if (num <= 0) return "";
        return String.valueOf(c).repeat(num);
    }
}
```

## 六、创建`data`层

新建`com.doooog.elmmybatis.mapper`包、`com.doooog.elmmybatis.sqlprovider`包

#### 1、`AdminMapper.java`接口

```java
package com.doooog.elmmybatis.mapper;

import com.doooog.elmmybatis.sqlprovider.AdminSqlProvider;
import com.doooog.elmmybatis.po.Admin;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface AdminMapper {
    @Results(id = "adminResults", value = {
            @Result(property = "aid", column = "aid", id = true),
            @Result(property = "aname", column = "aname"),
            @Result(property = "password", column = "password")
    })

@Select("select * from admin;")
    List<Admin> listAdminAll();

@Select("select * from admin where aname=#{username} and password=#{password}")
    @ResultMap("adminResults")
    Admin getAdminByLogin(@Param("username") String username, @Param("password") String password);

@Select("select * from admin where aid=#{aid}")
    @ResultMap("adminResults")
    Admin getAdminById(int aid);

@Insert("insert into admin(aname, password) values(#{aname},#{password})")
    int addAdmin(Admin admin);

@Insert("insert into admin values(#{aid},#{aname},#{password})")
    int addAdminWithId(Admin admin);

@Delete("delete from admin where aid=#{aid}")
    int deleteAdminById(int aid);

@UpdateProvider(type = AdminSqlProvider.class, method = "updateAdmin")
    int updateAdminById(Admin admin);

@Select("select count(aid) from admin where aname=#{aname}")
    int getAdminByName(String aname);
}
```

#### 2、`BusinessMapper.java`接口

```java
package com.doooog.elmmybatis.mapper;

import com.doooog.elmmybatis.po.Business;
import com.doooog.elmmybatis.sqlprovider.BusinessSqlProvider;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface BusinessMapper {

@Select("select * from business where bid=#{bid} and password=#{password}")
    @Results(id = "businessResults", value = {
            @Result(property = "bid", column = "bid", id = true),
            @Result(property = "password", column = "password"),
            @Result(property = "bname", column = "bname"),
            @Result(property = "address", column = "address"),
            @Result(property = "explain", column = "explain"),
            @Result(property = "startPrice", column = "deliveryPrice"),
            @Result(property = "foodList", column = "bid", javaType = List.class, many = @Many(select = "com.doooog.elmmybatis.mapper.FoodMapper.listFoodByBidLazy"))
    })
    Business getBusinessByLogin(@Param("bid") int bid, @Param("password") String password);

@Select("select * from business where bid=#{bid}")
    @ResultMap("businessResults")
    Business getBusinessById(int bid);

@Select("select * from business where bid=#{bid}")
    @Results({
            @Result(property = "bid", column = "bid", id = true),
            @Result(property = "password", column = "password"),
            @Result(property = "bname", column = "bname"),
            @Result(property = "address", column = "address"),
            @Result(property = "explain", column = "explain"),
            @Result(property = "startPrice", column = "deliveryPrice"),
    })
    Business getBusinessByIdLazy(int bid);

@Select("select * from business where bname=#{bname}")
    @ResultMap("businessResults")
    Business getBusinessByName(String bname);

@Select("select * from business where bname like concat('%',#{bname},'%')")
    @ResultMap("businessResults")
    List<Business> listBusinessByName(String bname);

@Select("select * from business")
    @ResultMap("businessResults")
    List<Business> listBusinessAll();

@Insert("insert into business(password, bname, address, `explain`, startPrice, deliveryPrice) values (#{password},#{bname},#{address},#{explain},#{startPrice},#{deliveryPrice})")
    @Options(useGeneratedKeys = true, keyProperty = "bid", keyColumn = "bid")
    int addBusiness(Business business);

@Insert("insert into business values (#{bid},#{password},#{bname},#{address},#{explain},#{startPrice},#{deliveryPrice})")
    @Options(useGeneratedKeys = true, keyProperty = "bid", keyColumn = "bid")
    int addBusinessWithId(Business business);

@UpdateProvider(type = BusinessSqlProvider.class, method = "updateBusinessById")
    int updateBusinessById(Business business);

@Delete("delete from business where bid=#{bid}")
    int deleteBusinessById(int bid);
}
```

#### 3、`FoodMapper.java`接口

```java
package com.doooog.elmmybatis.mapper;

import com.doooog.elmmybatis.po.Business;
import com.doooog.elmmybatis.po.Food;
import com.doooog.elmmybatis.sqlprovider.FoodSqlProvider;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface FoodMapper {
    @Select("select * from food where fid=#{fid}")
    @Results(id = "foodResults", value = {
            @Result(property = "fid", column = "fid", id = true),
            @Result(property = "fname", column = "fname"),
            @Result(property = "explain", column = "explain"),
            @Result(property = "price", column = "price"),
            @Result(property = "bid", column = "bid"),
            @Result(property = "business", column = "bid", javaType = Business.class, one = @One(select = "com.doooog.elmmybatis.mapper.BusinessMapper.getBusinessByIdLazy"))
    })
    Food getFoodById(int fid);

@Select("select * from food where fname=#{fname}")
    @ResultMap("foodResults")
    List<Food> getFoodByName(String fname);

@Select("select * from food where fname like concat('%',#{fname},'%')")
    @ResultMap("foodResults")
    List<Food> listFoodByName(String fname);

@Select("select * from food")
    @ResultMap("foodResults")
    List<Food> listFoodAll();

@Select("select * from food where food.bid=#{bid}")
    @Results({
            @Result(property = "fid", column = "fid", id = true),
            @Result(property = "fname", column = "fname"),
            @Result(property = "explain", column = "explain"),
            @Result(property = "price", column = "price"),
            @Result(property = "bid", column = "bid")
    })
    Food listFoodByBidLazy(int bid);

@UpdateProvider(type = FoodSqlProvider.class, method = "updateFoodById")
    int updateFoodById(Food food);

@Insert("insert into food ( fname, `explain`, price, bid) values (#{fname},#{explain},#{price},#{bid})")
    @Options(useGeneratedKeys = true, keyProperty = "fid", keyColumn = "fid")
    int addFood(Food food);

@Insert("insert into food values (#{fid},#{fname},#{explain},#{price},#{bid})")
    @Options(useGeneratedKeys = true, keyProperty = "fid", keyColumn = "fid")
    int addFoodWithId(Food food);

@Delete("delete from food where fid=#{fid}")
    int deleteFoodById(int fid);
}
```

#### 4、`AdminSqlProvider.java`类

```java
package com.doooog.elmmybatis.sqlprovider;

import com.doooog.elmmybatis.po.Admin;
import org.apache.ibatis.jdbc.SQL;

public class AdminSqlProvider {

public String updateAdmin(Admin admin) {
        return new SQL() {{
            UPDATE("admin");
            if (admin.getAname() != null && !admin.getAname().isEmpty())
                SET("aname=#{aname}");
            if (admin.getPassword() != null && !admin.getPassword().isEmpty())
                SET("password=#{password}");
            WHERE("aid=#{aid}");
        }}.toString();
    }
}
```

#### 5、`BusinessSqlProvider.java`类

```java
package com.doooog.elmmybatis.sqlprovider;

import com.doooog.elmmybatis.po.Business;
import org.apache.ibatis.jdbc.SQL;

public class BusinessSqlProvider {
    public String updateBusinessById(Business business) {
        return new SQL() {{
            UPDATE("business");
            if (business.getPassword() != null && !business.getPassword().isEmpty())
                SET("password=#{password}");
            if (business.getBname() != null && !business.getBname().isEmpty())
                SET("bname=#{bname}");
            if (business.getAddress() != null && !business.getAddress().isEmpty())
                SET("address=#{address}");
            if (business.getExplain() != null && !business.getExplain().isEmpty())
                SET("`explain`=#{explain}");
            if (business.getStartPrice() != null && business.getStartPrice() > 0)
                SET("startPrice=#{startPrice}");
            if (business.getDeliveryPrice() != null && business.getDeliveryPrice() > 0)
                SET("deliveryPrice=#{deliveryPrice}");
            WHERE("bid=#{bid}");
        }}.toString();
    }
}
```

#### 6、`FoodSqlProvider.java`类

```java
package com.doooog.elmmybatis.sqlprovider;

import com.doooog.elmmybatis.po.Food;
import org.apache.ibatis.jdbc.SQL;

public class FoodSqlProvider {
    public String updateFoodById(Food food) {
        return new SQL() {{
            UPDATE("food");
            if (food.getFname() != null && !food.getFname().isEmpty())
                SET("fname=#{fname}");
            if (food.getExplain() != null && !food.getExplain().isEmpty())
                SET("`explain`=#{explain}");
            if (food.getPrice() != null && food.getPrice() > 0)
                SET("price=#{price}");
            if (food.getBid() != null && food.getBid() > 0)
                SET("bid=#{bid}");
            WHERE("fid=#{fid}");
        }}.toString();
    }
}
```

## 七、创建`Controller`层

新建`com.doooog.elmmybatis.controller`包、`com.doooog.elmmybatis.controller.impl`包

#### 1、`AdminCtrl.java`接口

```java
package com.doooog.elmmybatis.controller;

import com.doooog.elmmybatis.po.Admin;
import java.util.List;

public interface AdminCtrl {
    // 管理员部分
    boolean login(String username, String password);

boolean addAdmin(Admin admin);

boolean deleteAdminById(int aid);

List<Admin> listAdminAll();

boolean updateAdminPasswordById(int aid, String oldPW, String newPW);

boolean getAdminById(int aid);
}
```

#### 2、`BusinessCtrl.java`接口

```java
package com.doooog.elmmybatis.controller;

import com.doooog.elmmybatis.po.Business;

import java.util.List;

public interface BusinessCtrl {
    // 商家部分
    Business login(int bid, String password);

boolean updateBusinessPasswordById(int bid, String oldPW, String newPW);

boolean updateBusinessNameById(int bid, String name);

boolean updateBusinessAddressById(int bid, String address);

boolean updateBusinessExplainById(int bid, String explain);

boolean updateBusinessPriceById(int bid,double startPrice, double deliveryPrice);

boolean deleteBusinessById(int bid);

boolean addBusiness(Business business);

boolean getBusinessById(int bid);

List<Business> listBusinessAll();
}
```

#### 3、`FoodCtrl.java`接口

```java
package com.doooog.elmmybatis.controller;

import com.doooog.elmmybatis.po.Food;

import java.util.List;

public interface FoodCtrl {
    Food getFoodById(int fid);

List<Food> listFoodAll();

List<Food> listFoodByName(String fname);

boolean addFood(Food food);

boolean updateFoodPriceById(int fid,double price);

boolean updateFoodById(Food food);

boolean deleteFoodById(int fid);
}
```

#### 4、`AdminCtrlImpl.java`类

```java
package com.doooog.elmmybatis.controller.impl;

import com.doooog.elmmybatis.controller.AdminCtrl;
import com.doooog.elmmybatis.mapper.AdminMapper;
import com.doooog.elmmybatis.po.Admin;
import com.doooog.elmmybatis.util.DBUtil;
import org.apache.ibatis.session.SqlSession;

import java.util.List;

public class AdminCtrlImpl implements AdminCtrl {

public boolean login(String username, String password) {
        if (username == null || password == null || username.isEmpty() || password.isEmpty()) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            AdminMapper adminMapper = sqlSession.getMapper(AdminMapper.class);
            Admin admin = adminMapper.getAdminByLogin(username, password);
            return admin != null && !admin.isEmpty();
        }
    }

@Override
    public boolean addAdmin(Admin admin) {
        if (admin == null) return false;
        if ((admin.getAid() == null || admin.getAid() <= 0) && !admin.isUnsafe(false)) {
            try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
                AdminMapper adminMapper = sqlSession.getMapper(AdminMapper.class);
                return adminMapper.addAdmin(admin) == 1;
            }
        } else if (!admin.isUnsafe(true)) {
            try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
                AdminMapper adminMapper = sqlSession.getMapper(AdminMapper.class);
                return adminMapper.addAdminWithId(admin) == 1;
            }
        }
        return false;
    }

@Override
    public boolean deleteAdminById(int aid) {
        if (aid <= 1) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            AdminMapper adminMapper = sqlSession.getMapper(AdminMapper.class);
            return adminMapper.deleteAdminById(aid) == 1;
        }
    }

@Override
    public List<Admin> listAdminAll() {
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            AdminMapper adminMapper = sqlSession.getMapper(AdminMapper.class);
            return adminMapper.listAdminAll();
        }
    }

@Override
    public boolean updateAdminPasswordById(int aid, String oldPW, String newPW) {
        if (aid <= 0 || oldPW == null || oldPW.isEmpty() || newPW == null || newPW.isEmpty()) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            AdminMapper adminMapper = sqlSession.getMapper(AdminMapper.class);
            Admin admin = adminMapper.getAdminById(aid);
            if (admin == null || !admin.getPassword().equals(oldPW)) return false;
            Admin tmp = new Admin();
            tmp.setAid(aid);
            tmp.setPassword(newPW);
            return adminMapper.updateAdminById(tmp) == 1;
        }
    }

@Override
    public boolean getAdminById(int aid) {
        if (aid <= 0) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            AdminMapper adminMapper = sqlSession.getMapper(AdminMapper.class);
            Admin admin = adminMapper.getAdminById(aid);
            if (admin == null) return false;
            System.out.println(admin);
            return true;
        }
    }
}
```

#### 5、`BusinessCtrlImpl.java`类

```java
package com.doooog.elmmybatis.controller.impl;

import com.doooog.elmmybatis.controller.BusinessCtrl;
import com.doooog.elmmybatis.mapper.BusinessMapper;
import com.doooog.elmmybatis.po.Business;
import com.doooog.elmmybatis.util.DBUtil;
import org.apache.ibatis.session.SqlSession;

import java.util.List;

public class BusinessCtrlImpl implements BusinessCtrl {

@Override
    public Business login(int bid, String password) {
        if (bid <= 0 || password == null || password.isEmpty()) return null;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
            return businessMapper.getBusinessByLogin(bid, password);
        }
    }

@Override
    public boolean addBusiness(Business business) {
        if (business == null) return false;
        if ((business.getBid() == null || business.getBid() <= 0) && !business.isUnsafe(false)) {
            try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
                BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
                int rs = businessMapper.addBusiness(business);
                return rs != 0;
            }
        } else if (!business.isUnsafe(true)) {
            try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
                BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
                int rs = businessMapper.addBusinessWithId(business);
                return rs != 0;
            }
        }
        return false;
    }

@Override
    public boolean deleteBusinessById(int bid) {
        if (bid <= 0) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
            return businessMapper.deleteBusinessById(bid) == 1;
        }
    }

@Override
    public boolean getBusinessById(int bid) {
        if (bid <= 0) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
            Business b = businessMapper.getBusinessById(bid);
            return b != null;
        }
    }

@Override
    public List<Business> listBusinessAll() {
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
            return businessMapper.listBusinessAll();
        }
    }

@Override
    public boolean updateBusinessPasswordById(int bid, String oldPW, String newPW) {
        if (bid <= 0 || oldPW == null || oldPW.isEmpty() || newPW == null || newPW.isEmpty()) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
            Business b = businessMapper.getBusinessById(bid);
            if (b == null || !b.getPassword().equals(oldPW)) return false;
            Business tmp = new Business();
            tmp.setBid(bid);
            tmp.setPassword(newPW);
            return businessMapper.updateBusinessById(tmp) == 1;
        }
    }

@Override
    public boolean updateBusinessNameById(int bid, String name) {
        if (bid <= 0 || name == null || name.isEmpty()) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
            Business tmp = new Business();
            tmp.setBid(bid);
            tmp.setBname(name);
            return businessMapper.updateBusinessById(tmp) == 1;
        }
    }

@Override
    public boolean updateBusinessAddressById(int bid, String address) {
        if (bid <= 0 || address == null || address.isEmpty()) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
            Business tmp = new Business();
            tmp.setBid(bid);
            tmp.setAddress(address);
            return businessMapper.updateBusinessById(tmp) == 1;
        }
    }

@Override
    public boolean updateBusinessExplainById(int bid, String explain) {
        if (bid <= 0 || explain == null || explain.isEmpty()) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
            Business tmp = new Business();
            tmp.setBid(bid);
            tmp.setExplain(explain);
            return businessMapper.updateBusinessById(tmp) == 1;
        }
    }

@Override
    public boolean updateBusinessPriceById(int bid, double startPrice, double deliveryPrice) {
        if (bid <= 0 || startPrice <= 0 || deliveryPrice <= 0) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            BusinessMapper businessMapper = sqlSession.getMapper(BusinessMapper.class);
            Business tmp = new Business();
            tmp.setBid(bid);
            tmp.setStartPrice(startPrice);
            tmp.setDeliveryPrice(deliveryPrice);
            return businessMapper.updateBusinessById(tmp) == 1;
        }
    }
}
```

#### 6、`FoodCtrlImpl.java`类

```java
package com.doooog.elmmybatis.controller.impl;

import com.doooog.elmmybatis.controller.FoodCtrl;
import com.doooog.elmmybatis.mapper.FoodMapper;
import com.doooog.elmmybatis.po.Food;
import com.doooog.elmmybatis.util.DBUtil;
import org.apache.ibatis.session.SqlSession;

import java.util.List;

public class FoodCtrlImpl implements FoodCtrl {
    @Override
    public Food getFoodById(int fid) {
        if (fid <= 0) return null;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            FoodMapper foodMapper = sqlSession.getMapper(FoodMapper.class);
            return foodMapper.getFoodById(fid);
        }
    }

@Override
    public List<Food> listFoodAll() {
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            FoodMapper foodMapper = sqlSession.getMapper(FoodMapper.class);
            return foodMapper.listFoodAll();
        }
    }

@Override
    public List<Food> listFoodByName(String fname) {
        if (fname == null || fname.isEmpty()) return null;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            FoodMapper foodMapper = sqlSession.getMapper(FoodMapper.class);
            return foodMapper.listFoodByName(fname);
        }
    }

@Override
    public boolean addFood(Food food) {
        if (food == null || food.isEmpty()) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            FoodMapper foodMapper = sqlSession.getMapper(FoodMapper.class);
            if ((food.getFid() == null || food.getFid() <= 0) && !food.isUnsafe(false)) {
                return foodMapper.addFood(food) > 0;
            } else if (!food.isUnsafe(true)) {
                return foodMapper.addFoodWithId(food) > 0;
            }
            return false;
        }

}

@Override
    public boolean updateFoodPriceById(int fid, double price) {
        if (fid <= 0 || price <= 0) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            FoodMapper foodMapper = sqlSession.getMapper(FoodMapper.class);
            Food tmp = new Food();
            tmp.setFid(fid);
            tmp.setPrice(price);
            return foodMapper.updateFoodById(tmp) > 0;
        }
    }

@Override
    public boolean updateFoodById(Food food) {
        if (food == null || food.isEmpty() || food.isUnsafe(true)) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            FoodMapper foodMapper = sqlSession.getMapper(FoodMapper.class);
            return foodMapper.updateFoodById(food) > 0;
        }
    }

@Override
    public boolean deleteFoodById(int fid) {
        if (fid <= 0) return false;
        try (SqlSession sqlSession = DBUtil.getSqlSessionFactory().openSession()) {
            FoodMapper foodMapper = sqlSession.getMapper(FoodMapper.class);
            return foodMapper.deleteFoodById(fid) > 0;
        }
    }
}
```

## 八、创建`view`层

新建`com.doooog.elmmybatis.view`包

#### 1、`MainEntry.java`类

```java
package com.doooog.elmmybatis.view;

import com.doooog.elmmybatis.util.CommonUtil;
import com.doooog.elmmybatis.util.InputUtil;

public class MainEntry {
    public static void main(String[] args) {
        boolean exit = false;
        while (!exit) {
            System.out.println(CommonUtil.copyChar('=', 30));
            System.out.println("|-- 欢迎进入饿了么后台管理系统 --|");
            System.out.println("|-- 1.系统管理员  2.商家");
            System.out.print("|-- 请输入编号(0.退出):");
            int choice = InputUtil.menuInputInteger("(1或2或0)");
            switch (choice) {
                case 0 -> exit = true;
                case 1 -> new AdminView().menuLogin();
                case 2 -> new BusinessView().menuLogin();
                default -> {
                }
            }
        }
    }
}
```

#### 2、`AdminView.java`类

```java
package com.doooog.elmmybatis.view;

import com.doooog.elmmybatis.controller.AdminCtrl;
import com.doooog.elmmybatis.controller.BusinessCtrl;
import com.doooog.elmmybatis.controller.impl.AdminCtrlImpl;
import com.doooog.elmmybatis.controller.impl.BusinessCtrlImpl;
import com.doooog.elmmybatis.po.Admin;
import com.doooog.elmmybatis.po.Business;
import com.doooog.elmmybatis.util.CommonUtil;
import com.doooog.elmmybatis.util.InputUtil;

import java.util.List;

public class AdminView {
    private AdminCtrl adminCtrl = new AdminCtrlImpl();
    private BusinessCtrl businessCtrl = new BusinessCtrlImpl();

public void menuLogin() {
        System.out.println("|-- 请使用管理员身份进行登录 --|");
        System.out.print("|-- 请输入用户名:");
        String username = InputUtil.menuInputString("");
        System.out.print("|-- 请输入密码:");
        String password = InputUtil.menuInputString("");
        if (adminCtrl.login(username, password)) {
            System.out.println("登录成功!");
            menuMain();
        } else {
            System.out.println("登录失败，请检查账号或密码是否有误!");
        }
    }

private void menuMain() {
        boolean exit = false;
        while (!exit) {
            System.out.println(CommonUtil.copyChar('=', 30));
            System.out.println("|--        管理员菜单        --|");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.println("|-- 1.管理员操作");
            System.out.println("|-- 2.管理商家");
            System.out.println("|-- 0.退出登录");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.print("|-- 请输入编号(0~2整数):");
            int choice = InputUtil.menuInputInteger("(0~2整数)");
            switch (choice) {
                case 0 -> exit = true;
                case 1 -> menuAdmin();
                case 2 -> menuBusiness();
                default -> {
                }
            }
        }
    }

private void menuAdmin() {
        boolean exit = false;
        while (!exit) {
            System.out.println(CommonUtil.copyChar('=', 30));
            System.out.println("|--        管理员菜单        --|");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.println("|-- 1.查看所有管理员");
            System.out.println("|-- 2.新增管理员");
            System.out.println("|-- 3.更改管理员密码");
            System.out.println("|-- 4.删除管理员");
            System.out.println("|-- 0.返回上一页");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.print("|-- 请输入编号(0~4整数):");
            int choice = InputUtil.menuInputInteger("(0~4整数)");
            switch (choice) {
                case 0 -> exit = true;
                case 1 -> menuListAdminAll();
                case 2 -> menuAddAdmin();
                case 3 -> menuRePasswordAdmin();
                case 4 -> menuDeleteAdmin();
                default -> {
                }
            }
        }
    }

private void menuBusiness() {
        boolean exit = false;
        while (!exit) {
            System.out.println(CommonUtil.copyChar('=', 30));
            System.out.println("|--        管理员菜单        --|");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.println("|-- 1.查看所有商家");
            System.out.println("|-- 2.新增商家");
            System.out.println("|-- 3.更改商家密码");
            System.out.println("|-- 4.更改商家名称");
            System.out.println("|-- 5.更改商家地址");
            System.out.println("|-- 6.更改商家介绍");
            System.out.println("|-- 7.更改商家配送价格");
            System.out.println("|-- 8.删除商家");
            System.out.println("|-- 0.返回上一页");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.print("|-- 请输入编号(0~12整数):");
            int choice = InputUtil.menuInputInteger("(0~12整数)");
            switch (choice) {
                case 0 -> exit = true;
                case 1 -> menuListBusinessAll();
                case 2 -> menuAddBusiness();
                case 3 -> menuRePasswordBusiness();
                case 4 -> menuRenameBusiness();
                case 5 -> menuReAddress();
                case 6 -> menuReExplain();
                case 7 -> menuRePrice();
                case 8 -> menuDeleteBusiness();
                default -> {
                }
            }
        }
    }

private void menuListBusinessAll() {
        List<Business> list = businessCtrl.listBusinessAll();
        if (list == null || list.isEmpty()) {
            System.out.println("未查询到信息");
            return;
        }
        for (Business business : list) {
            System.out.println(business);
        }
    }

private void menuListAdminAll() {
        List<Admin> list = adminCtrl.listAdminAll();
        if (list == null || list.isEmpty()) {
            System.out.println("未查询到信息");
            return;
        }
        for (Admin admin : list) {
            System.out.println(admin);
        }
    }

private void menuAddAdmin() {
        Admin admin = new Admin();
        int tmp;
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- ID(整数):");
        tmp = InputUtil.menuInputInteger("(请输入整数,或0跳过)");
        if (tmp == -1) return;
        if (tmp != 0) admin.setAid(tmp);
        System.out.print("|-- 账号(字母+数字)(必填):");
        tmp2 = InputUtil.menuInputString("(字母+数字)(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        admin.setAname(tmp2);
        System.out.print("|-- 密码(字母+数字)(必填):");
        tmp2 = InputUtil.menuInputString("(字母+数字)(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        admin.setPassword(tmp2);
        if (adminCtrl.addAdmin(admin)) {
            System.out.println("添加成功!");
            return;
        }
        System.out.println("添加失败,请检查输入是否有误,ID可以为空");
    }

private void menuRePasswordAdmin() {
        Admin admin = new Admin();
        int tmp;
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 需要更改的ID(整数)(必填):");
        tmp = InputUtil.menuInputInteger("(整数)提取方法…");
        if (tmp == -1 || tmp == 0) return;
        admin.setAid(tmp);
        System.out.print("|-- 旧密码(字母+数字)(必填):");
        tmp2 = InputUtil.menuInputString("(字母+数字)(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        admin.setAname(tmp2);
        System.out.print("|-- 新密码(字母+数字)(必填):");
        tmp2 = InputUtil.menuInputString("(字母+数字)(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        admin.setPassword(tmp2);
        if (adminCtrl.updateAdminPasswordById(admin.getAid(), admin.getAname(), admin.getPassword())) {
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuDeleteAdmin() {
        int tmp;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 需要删除的ID(0以上整数)(必填):");
        tmp = InputUtil.menuInputInteger("(0以上整数)");
        if (tmp == -1) return;
        if (!adminCtrl.getAdminById(tmp)) {
            System.out.println("未查询到信息");
            return;
        }
        if (!doChoice()) return;
        if (adminCtrl.deleteAdminById(tmp)) {
            System.out.println("删除成功!");
            return;
        }
        System.out.println("删除失败,未知错误");
    }

private void menuAddBusiness() {
        Business business = new Business();
        double tmp;
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");

System.out.print("|-- 名称(必填):");
        tmp2 = InputUtil.menuInputString("(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        business.setBname(tmp2);

System.out.print("|-- 密码(字母+数字)(必填):");
        tmp2 = InputUtil.menuInputString("(字母+数字)(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        business.setPassword(tmp2);

System.out.print("|-- 地址:");
        tmp2 = InputUtil.menuInputString("");
        if (tmp2.equals("-1")) return;
        if (!tmp2.equals("0")) business.setAddress(tmp2);

System.out.print("|-- 介绍:");
        tmp2 = InputUtil.menuInputString("");
        if (tmp2.equals("-1")) return;
        if (!tmp2.equals("0")) business.setExplain(tmp2);

System.out.print("|-- 起送价格:");
        tmp = InputUtil.menuInputDouble("");
        if (tmp == -1) return;
        if (tmp != 0) business.setStartPrice(tmp);

System.out.print("|-- 配送价格:");
        tmp = InputUtil.menuInputDouble("");
        if (tmp == -1) return;
        if (tmp != 0) business.setDeliveryPrice(tmp);

System.out.print("|-- 确认信息:");
        System.out.println(business);
        if (!doChoice()) return;

if (businessCtrl.addBusiness(business)) {
            System.out.println("添加成功!");
            System.out.println("您用于登录的编号为:" + business.getBid());
            return;
        }
        System.out.println("添加失败,请检查输入是否有误");
    }

private void menuRePasswordBusiness() {
        Business business = new Business();
        int tmp;
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 需要更改的ID(整数)(必填):");
        tmp = InputUtil.menuInputInteger("(整数)(必填)");
        if (tmp == -1 || tmp == 0) return;
        business.setBid(tmp);
        System.out.print("|-- 旧密码(字母+数字)(必填):");
        tmp2 = InputUtil.menuInputString("(字母+数字)(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        business.setBname(tmp2);
        System.out.print("|-- 新密码(字母+数字)(必填):");
        tmp2 = InputUtil.menuInputString("(字母+数字)(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        business.setPassword(tmp2);
        if (businessCtrl.updateBusinessPasswordById(business.getBid(), business.getBname(), business.getPassword())) {
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuRenameBusiness() {
        int tmp;
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 需要更改的ID(整数)(必填):");
        tmp = InputUtil.menuInputInteger("(整数)(必填)");
        if (tmp == -1 || tmp == 0) return;
        System.out.print("|-- 新名称(必填):");
        tmp2 = InputUtil.menuInputString("(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        if (businessCtrl.updateBusinessNameById(tmp, tmp2)) {
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuReAddress() {
        int tmp;
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 需要更改的ID(整数)(必填):");
        tmp = InputUtil.menuInputInteger("(整数)(必填)");
        if (tmp == -1 || tmp == 0) return;
        System.out.print("|-- 新地址(必填):");
        tmp2 = InputUtil.menuInputString("(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        if (businessCtrl.updateBusinessAddressById(tmp, tmp2)) {
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuReExplain() {
        int tmp;
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 需要更改的ID(整数)(必填):");
        tmp = InputUtil.menuInputInteger("(整数)(必填)");
        if (tmp == -1 || tmp == 0) return;
        System.out.print("|-- 新介绍(必填):");
        tmp2 = InputUtil.menuInputString("(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        if (businessCtrl.updateBusinessExplainById(tmp, tmp2)) {
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuRePrice() {
        int tmp;
        double tmp2, tmp3;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 需要更改的ID(整数)(必填):");
        tmp = InputUtil.menuInputInteger("(整数)(必填)");
        if (tmp == -1 || tmp == 0) return;
        System.out.print("|-- 新起送价(大于0的小数)(必填):");
        tmp2 = InputUtil.menuInputDouble("(大于0的小数)(必填)");
        if (tmp2 == -1 || tmp2 == 0) return;
        System.out.print("|-- 新配送价(大于0的小数)(必填):");
        tmp3 = InputUtil.menuInputDouble("(大于0的小数)(必填)");
        if (tmp3 == -1 || tmp3 == 0) return;
        if (businessCtrl.updateBusinessPriceById(tmp, tmp2, tmp3)) {
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuDeleteBusiness() {
        int tmp;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 需要删除的ID(整数)(必填):");
        tmp = InputUtil.menuInputInteger("(整数)(必填)");
        if (tmp == -1 || tmp == 0) return;
        if (!businessCtrl.getBusinessById(tmp)) {
            System.out.println("未查询到信息");
            return;
        }
        if (!doChoice()) return;
        if (businessCtrl.deleteBusinessById(tmp)) {
            System.out.println("删除成功!");
            return;
        }
        System.out.println("删除失败,请检查输入是否有误");
    }

private boolean doChoice() {
        System.out.print("|-- 确认无误(1.是,2.否):");
        int tmp = InputUtil.menuInputInteger("(1.是,2.否)");
        return tmp == 1;
    }
}
```

#### 3、`BusinessView.java`类

```java
package com.doooog.elmmybatis.view;

import com.doooog.elmmybatis.controller.BusinessCtrl;
import com.doooog.elmmybatis.controller.FoodCtrl;
import com.doooog.elmmybatis.controller.impl.BusinessCtrlImpl;
import com.doooog.elmmybatis.controller.impl.FoodCtrlImpl;
import com.doooog.elmmybatis.po.Business;
import com.doooog.elmmybatis.po.Food;
import com.doooog.elmmybatis.util.CommonUtil;
import com.doooog.elmmybatis.util.InputUtil;

import java.util.List;

public class BusinessView {
    private BusinessCtrl businessCtrl = new BusinessCtrlImpl();
    private FoodCtrl foodCtrl = new FoodCtrlImpl();
    private Business my;
    private boolean exit2;

public void menuLogin() {
        System.out.println("|-- 请使用商家身份进行登录 --|");
        System.out.print("|-- 请输入商家编号:");
        int username = InputUtil.menuInputInteger("");
        System.out.print("|-- 请输入密码:");
        String password = InputUtil.menuInputString("");
        my = businessCtrl.login(username, password);
        if (my != null && !my.isEmpty()) {
            System.out.println("登录成功!");
            menuMain();
        } else {
            System.out.println("登录失败，请检查账号或密码是否有误!");
        }
    }

private void menuMain() {
        boolean exit = false;
        while (!exit) {
            if (exit2) {
                exit = true;
                continue;
            }
            System.out.println(CommonUtil.copyChar('=', 30));
            System.out.println("|--        商家菜单        --|");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.println("|-- 1.账号操作");
            System.out.println("|-- 2.食物操作");
            System.out.println("|-- 0.退出登录");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.print("|-- 请输入编号(0~2整数):");
            int choice = InputUtil.menuInputInteger("(0~2整数)");
            switch (choice) {
                case 0 -> exit = true;
                case 1 -> menuBusiness();
                case 2 -> menuFood();
                default -> {
                }
            }
        }
    }

private void menuBusiness() {
        boolean exit = false;
        while (!exit) {
            System.out.println(CommonUtil.copyChar('=', 30));
            System.out.println("|--        账号操作        --|");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.println("|-- 1.修改密码");
            System.out.println("|-- 2.更改名称");
            System.out.println("|-- 3.更改介绍");
            System.out.println("|-- 4.更改地址");
            System.out.println("|-- 5.更改配送价格");
            System.out.println("|-- 6.注销商家");
            System.out.println("|-- 0.返回上一页");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.print("|-- 请输入编号(0~6整数):");
            int choice = InputUtil.menuInputInteger("(0~6整数)");
            switch (choice) {
                case 0 -> exit = true;
                case 1 -> menuUpdatePassword();
                case 2 -> menuUpdateName();
                case 3 -> menuUpdateExplain();
                case 4 -> menuUpdateAddress();
                case 5 -> menuUpdatePrice();
                case 6 -> {
                    menuDeleteBusiness();
                    exit2 = true;
                    exit = true;
                }
                default -> {
                }
            }
        }
    }

private void menuFood() {
        boolean exit = false;
        while (!exit) {
            System.out.println(CommonUtil.copyChar('=', 30));
            System.out.println("|--        食物操作        --|");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.println("|-- 1.查看所有食物");
            System.out.println("|-- 2.搜索食物名称");
            System.out.println("|-- 3.新增食物");
            System.out.println("|-- 4.修改食物价格");
            System.out.println("|-- 5.修改食物信息");
            System.out.println("|-- 6.删除食物");
            System.out.println("|-- 0.返回上一页");
            System.out.println(CommonUtil.copyChar('-', 30));
            System.out.print("|-- 请输入编号(0~6整数):");
            int choice = InputUtil.menuInputInteger("(0~6整数)");
            switch (choice) {
                case 0 -> exit = true;
                case 1 -> menuListFoodAll();
                case 2 -> menuSearchFoodByName();
                case 3 -> menuAddFood();
                case 4 -> menuUpdateFoodPrice();
                case 5 -> menuUpdateFood();
                case 6 -> menuDeleteFood();
                default -> {
                }
            }
        }
    }

private void menuUpdatePassword() {
        Business b = my.copy();
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 旧密码(字母+数字)(必填):");
        tmp2 = InputUtil.menuInputString("(字母+数字)(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        b.setBname(tmp2);
        System.out.print("|-- 新密码(字母+数字)(必填):");
        tmp2 = InputUtil.menuInputString("(字母+数字)(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        b.setPassword(tmp2);
        if (businessCtrl.updateBusinessPasswordById(b.getBid(), b.getBname(), b.getPassword())) {
            my.setPassword(b.getPassword());
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuUpdateName() {
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 新名称(必填):");
        tmp2 = InputUtil.menuInputString("(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        if (businessCtrl.updateBusinessNameById(my.getBid(), tmp2)) {
            my.setBname(tmp2);
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuUpdateExplain() {
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 新介绍(必填):");
        tmp2 = InputUtil.menuInputString("(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        if (businessCtrl.updateBusinessExplainById(my.getBid(), tmp2)) {
            my.setExplain(tmp2);
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuUpdateAddress() {
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 新地址(必填):");
        tmp2 = InputUtil.menuInputString("(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        if (businessCtrl.updateBusinessAddressById(my.getBid(), tmp2)) {
            my.setAddress(tmp2);
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuUpdatePrice() {
        double tmp2, tmp3;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 新起送价(大于0的小数)(必填):");
        tmp2 = InputUtil.menuInputDouble("(大于0的小数)(必填)");
        if (tmp2 == -1 || tmp2 == 0) return;
        System.out.print("|-- 新配送价(大于0的小数)(必填):");
        tmp3 = InputUtil.menuInputDouble("(大于0的小数)(必填)");
        if (tmp3 == -1 || tmp3 == 0) return;
        if (businessCtrl.updateBusinessPriceById(my.getBid(), tmp2, tmp3)) {
            my.setStartPrice(tmp2);
            my.setDeliveryPrice(tmp3);
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuDeleteBusiness() {
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.println(my);
        if (!doChoice()) return;
        if (businessCtrl.deleteBusinessById(my.getBid())) {
            System.out.println("删除成功!");
            return;
        }
        System.out.println("删除失败,请检查输入是否有误");
    }

private void menuListFoodAll() {
        List<Food> list = foodCtrl.listFoodAll();
        if (list == null || list.isEmpty()) {
            System.out.println("未查询到信息");
            return;
        }
        for (Food f : list) {
            System.out.println(f);
        }
    }

private void menuSearchFoodByName() {
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        System.out.print("|-- 食物名称(模糊)(必填):");
        tmp2 = InputUtil.menuInputString("(模糊)(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        List<Food> list = foodCtrl.listFoodByName(tmp2);
        if (list == null || list.isEmpty()) {
            System.out.println("未查询到信息");
            return;
        }
        for (Food f : list) {
            System.out.println(f);
        }
    }

private void menuAddFood() {
        Food food = new Food();
        double tmp;
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");

System.out.print("|-- 食物名称(必填):");
        tmp2 = InputUtil.menuInputString("(必填)");
        if (tmp2.equals("-1") || tmp2.equals("0")) return;
        food.setFname(tmp2);

System.out.print("|-- 介绍:");
        tmp2 = InputUtil.menuInputString("");
        if (tmp2.equals("-1")) return;
        if (!tmp2.equals("0")) food.setExplain(tmp2);

System.out.print("|-- 价格(必填):");
        tmp = InputUtil.menuInputDouble("");
        if (tmp == -1 || tmp == 0) return;
        food.setPrice(tmp);
        food.setBid(my.getBid());
        System.out.print("|-- 确认信息:");
        System.out.println(food);
        if (!doChoice()) return;

if (foodCtrl.addFood(food)) {
            System.out.println("添加成功!");
            return;
        }
        System.out.println("添加失败,请检查输入是否有误");
    }

private void menuUpdateFoodPrice() {
        int tmp;
        double tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        menuListFoodAll();
        System.out.print("|-- 食物ID(大于0的整数)(必填):");
        tmp = InputUtil.menuInputInteger("(大于0的整数)(必填)");
        if (tmp == -1 || tmp == 0) return;
        System.out.print("|-- 新价格(大于0的小数)(必填):");
        tmp2 = InputUtil.menuInputDouble("(大于0的小数)(必填)");
        if (tmp2 == -1 || tmp2 == 0) return;
        if (foodCtrl.updateFoodPriceById(tmp, tmp2)) {
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuUpdateFood() {
        int id;
        double tmp;
        String tmp2;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        menuListFoodAll();
        System.out.print("|-- 需要修改的食物ID(大于0的整数)(必填):");
        id = InputUtil.menuInputInteger("(大于0的整数)(必填)");
        if (id == -1 || id == 0) return;
        Food food = foodCtrl.getFoodById(id);
        if (food == null || food.isEmpty()) {
            System.out.println("未查询到信息");
            return;
        }

System.out.print("|-- 食物名称(" + food.getFname() + "):");
        tmp2 = InputUtil.menuInputString("(" + food.getFname() + ")");
        if (tmp2.equals("-1")) return;
        if (!tmp2.equals("0")) food.setFname(tmp2);

System.out.print("|-- 介绍:");
        tmp2 = InputUtil.menuInputString("");
        if (tmp2.equals("-1")) return;
        if (!tmp2.equals("0")) food.setExplain(tmp2);

System.out.print("|-- 价格(" + food.getPrice() + "):");
        tmp = InputUtil.menuInputDouble("(" + food.getPrice() + ")");
        if (tmp == -1) return;
        if (tmp != 0) food.setPrice(tmp);
        System.out.print("|-- 确认信息:");
        System.out.println(food);
        if (!doChoice()) return;

if (foodCtrl.updateFoodById(food)) {
            System.out.println("修改成功!");
            return;
        }
        System.out.println("修改失败,请检查输入是否有误");
    }

private void menuDeleteFood() {
        int id;
        System.out.println(CommonUtil.copyChar('=', 30));
        System.out.println("|-- 没有(必填)项输入0可跳过,输入-1返回上级菜单");
        menuListFoodAll();
        System.out.print("|-- 需要删除的食物ID(大于0的整数)(必填):");
        id = InputUtil.menuInputInteger("(大于0的整数)(必填)");
        if (id == -1 || id == 0) return;
        Food food = foodCtrl.getFoodById(id);
        if (food == null || food.isEmpty()) {
            System.out.println("未查询到信息");
            return;
        }
        System.out.print("|-- 确认信息:");
        System.out.println(food);
        if (!doChoice()) return;

if (foodCtrl.deleteFoodById(id)) {
            System.out.println("删除成功!");
            return;
        }
        System.out.println("删除失败,请检查输入是否有误");
    }

private boolean doChoice() {
        System.out.print("|-- 确认无误(1.是,2.否):");
        int tmp = InputUtil.menuInputInteger("(1.是,2.否)");
        return tmp == 1;
    }
}
```

## 九、总结

与JDBC的相比，MyBatis的`elm`实现了动态SQL，并且通过全注解去创建`Mapper`，另外优化了界面的操作逻辑。

项目编写思路：

① 导入依赖库 -> ② 创建数据库表对应的实例化对象 -> ③ 创建通用工具 -> ④ 写数据层接口及其实现类 -> ⑤ 写控制层接口及其实现类 -> ⑥ 根据控制层构建前端内容 -> ⑦ 根据前端需求修改控制层及数据层内容 -> ⑧ 优化前端逻辑