MyBatis(五天掌握之第二天)

MyBatis巩固步骤：
1. 编写JavaBean：为每一张表编写对应的JavaBean
2. 编写业务类Mapper
3. 编写核心配置文件
4. 编写测试类

Mapper

//1 只需要编辑接口
//2 编写功能方法，并为每一个方法添加功能注解

// 常见注解
@Select		//查询，方法返回值：JavaBean、List、Map等
@Insert		//添加，方法返回值：Integer
@Update		//更新，方法返回值：Integer
@Delete		//删除，方法返回值：Integer

测试类

//1 加载配置文件
InputStream is = Resources.getSourceAsStream("xxx.xml");
//2 获得工厂
SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
//3 通过工厂获得会话(连接)
SqlSession session = factory.openSession();
//4 通过会话获得功能接口
UserMapper userMapper = session.getMapper(UserMapper.class);
//5 执行功能方法
// 提交事务
session.commit();
//6 处理结果
//7 释放资源
session.close();

1.核心配置文件详解 1.1 properties

使用 properties 抽取经常修改的内容

方式1：直接抽取

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方式2：将进行修改的内容抽取到properties文件中

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/ssm_db1
jdbc.username=root
jdbc.password=1234

1.2 settings

开启驼峰映射
```
    
    
        
        
    
```

1.3 mappers

加载一个类
```
    
        
         
    
```
加载一个包
```
    
        
        
    
```

2 API详解 2.1 输入：vo条件

编写Vo，条件查询封装类

package com.czxy.ssm.vo;


public class UserVo {
    private String beginTime;
    private String endTime;
    public String getBeginTime() {
        return beginTime;
    }
    public void setBeginTime(String beginTime) {
        this.beginTime = beginTime;
    }
    public String getEndTime() {
        return endTime;
    }
    public void setEndTime(String endTime) {
        this.endTime = endTime;
    }
}

编写功能接口

    
    @Select("SELECT * FROM `user` WHERe birthday >= #{beginTime} AND birthday <= #{endTime}")
    public List condition(UserVo userVo);

测试

package com.czxy.ssm;

import com.czxy.ssm.domain.User;
import com.czxy.ssm.mapper.UserMapper;
import com.czxy.ssm.utils.MyBatisUtils;
import com.czxy.ssm.vo.UserVo;

import java.io.IOException;
import java.util.List;


public class Test06_Condition {
   public static void main(String[] args) throws IOException {

       //1 通过会话获得功能接口
       UserMapper userMapper = MyBatisUtils.getMapper(UserMapper.class);
       //2 更新
       UserVo userVo = new UserVo();
       userVo.setBeginTime("2010");
       userVo.setEndTime("2020");
       List list = userMapper.condition(userVo);
       // 打印结果
       list.forEach(System.out::println);
       //3 提交并关闭
       MyBatisUtils.commitAndclose();
   }
}

2.2 输出：结果集映射

结果集映射：查询结果与 JavaBean之间的映射关系。表的列名和JavaBean的属性名对应关系。
@Results 用于配置JavaBean和表的映射关系的
- @Result 配置JavaBean一个属性和表的一个列之间对应关系。
@ResultMap 共享已经映射关系
实例1：JavaBean和表映射关系

    @Select("select * from user")
    @Results({
            @Result(column = "user_name",property = "userName"),
            @Result(column = "password", property = "password")
    })
    public List selectAll();

实例2：共享映射关系

  @Select("SELECT * FROM `user` WHERe `name` LIKE '%${name}%'")
  @ResultMap("userResultMap")
  public List selectByName(@Param("name") String name);

3. 多表操作：一对多 3.1 JavaBean 3.1.1 编写JavaBean：User

public class User {
    private String uid;
    private String userName;
    private String password;
    private String name;
    private String email;
    private Date birthday;
    private String sex;
    private Integer state;
    private String code;

3.1.2 编写JavaBean：Order

public class Order {
    private String oid; 		// 订单编号
    private Date ordertime; 	// 下单时间
    private Double total; 		// 订单总金额
    private Integer state; 		// 订单状态 0 未支付 1 已支付 2已发货 3已收货
    private String address;		// 收货人地址
    private String name;		// 收货人姓名
    private String telephone;	// 收货人电话
    private String uid;

3.1.3 编写对应关系

public class User {
    // 一对多关系：一个用户拥有多个订单
    private List orderList = new ArrayList<>()

3.2 编写各自Mapper 3.2.1 编写UserMapper

package com.czxy.ssm.mapper;

import com.czxy.ssm.domain.User;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import java.util.List;


public interface UserMapper {

    
    @Select("select * from user")
    @Results(id="userResultMap", value={
            @Result(column = "user_name",property = "userName"),
            @Result(column = "password", property = "password")
    })
    public List selectAll();
}

3.2.2 编写OrderMapper

查询指定用户的所有的订单

package com.czxy.ssm.mapper;

import com.czxy.ssm.domain.Order;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

import java.util.List;


public interface OrderMapper {

    
    @Select("SELECT * FROM orders WHERe uid = #{uid}")
    public List selectAllByUid(@Param("uid") String uid);
}

3.3 测试类 3.3.1 user测试

package com.czxy.ssm;

import com.czxy.ssm.domain.User;
import com.czxy.ssm.mapper.UserMapper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;


public class Test01_SelectAll {
    public static void main(String[] args) throws IOException {
        //1 加载配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2 获得工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //3 通过工程获得会话（连接）
        SqlSession sqlSession = factory.openSession();
        //4 获得功能接口
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        //5 进行查询
        List list = userMapper.selectAll();
        //6 处理数据
        for(User user: list) {
            System.out.println(user);
        }
        //7 释放资源
        sqlSession.close();
    }
}

3.3.2 order测试

package com.czxy.ssm;

import com.czxy.ssm.domain.Order;
import com.czxy.ssm.domain.User;
import com.czxy.ssm.mapper.OrderMapper;
import com.czxy.ssm.mapper.UserMapper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;


public class Test02_SelectAllOrderByUId {
    public static void main(String[] args) throws IOException {
        //1 加载配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2 获得工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //3 通过工程获得会话（连接）
        SqlSession sqlSession = factory.openSession();
        //4 获得功能接口
        OrderMapper orderMapper = sqlSession.getMapper(OrderMapper.class);
        //5 进行查询
        List list = orderMapper.selectAllByUid("u001");
        //6 处理数据
        list.forEach(System.out::println);
        //7 释放资源
        sqlSession.close();
    }
}

3.4 映射关系

查询所有用户的同时，关联查询每一个用户的所有的订单。

package com.czxy.ssm.mapper;

import com.czxy.ssm.domain.User;
import org.apache.ibatis.annotations.Many;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import java.util.List;


public interface UserMapper {

    
    @Select("select * from user")
    @Results(id="userResultMap", value={
            @Result(property = "uid", column = "uid"),
            @Result(property = "userName", column = "user_name"),
            @Result(property = "password", column = "password"),
            @Result(property = "orderList",column = "uid", many=@Many(select = "com.czxy.ssm.mapper.OrderMapper.selectAllByUid"))
    })
    public List selectAll();
}

4. 多表操作：多对一 4.1 分析

目标：查询订单的同时，可以查询所有的用户
步骤：
1. 修改OrderMapper，通过id查询订单详情
2. 测试类 order详情
3. 修改Order，添加User属性
4. 修改UserMapper，通过id查询用户详情
5. 修改OrderMapper，建立关联

4.2 OrderMapper 详情

public interface OrderMapper {

    
    @Select("select * from orders where oid = #{oid}")
    public Order selectById(@Param("oid") String oid);
}

4.3 测试类 order详情

package com.czxy.ssm;

import com.czxy.ssm.domain.Order;
import com.czxy.ssm.mapper.OrderMapper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;


public class Test03_SelectOrderByOId {
    public static void main(String[] args) throws IOException {
        //1 加载配置文件
        InputStream is = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2 获得工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(is);
        //3 通过工程获得会话（连接）
        SqlSession sqlSession = factory.openSession();
        //4 获得功能接口
        OrderMapper orderMapper = sqlSession.getMapper(OrderMapper.class);
        //5 进行查询
        Order order = orderMapper.selectById("x001");
        //6 处理数据
        System.out.println(order);
        //7 释放资源
        sqlSession.close();
    }
}

4.4 修改Order

public class Order {    // 多对一：多个订单属于一个用户    private User user;

4.5 UserMapper 详情

public interface UserMapper {

    
    @Select("select * from user where uid = #{uid}")
    public User selectById(@Param("uid") String uid);
}

4.6 修改OrderMapper，建立关联

package com.czxy.ssm.mapper;

import com.czxy.ssm.domain.Order;
import org.apache.ibatis.annotations.*;

import java.util.List;


public interface OrderMapper {

    
    @Select("select * from orders where oid = #{oid}")
    @Results({
            @Result(property = "user", column = "uid" , one = @One(select="com.czxy.ssm.mapper.UserMapper.selectById"))
    })
    public Order selectById(@Param("oid") String oid);
}

MyBatis(五天掌握之第二天)

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