Mybatis返回Map数据方式示例

目录

• 一. 方式1
• 接口
• 调用
• 二. 方式2
• 接口
• 调用
• 三. 方式3
• 接口
• 调用

一. 方式1

接口

public interface UserMapper {

    List> selectTestData1();
}

    
        SELECT
          t_user.id as id,
	      t_user.email as email,
	      t_user.avatar as avatar
        FROM
	      t_user
    

调用

@Service
public class MapTest implements CommandLineRunner {

    @Autowired
    private UserMapper mapper;

    @Override
    public void run(String... args) throws Exception {

        List> listData1 = mapper.selectTestData1();
        for (Map map : listData1) {
            System.out.println(map);
        }
    }
}

二. 方式2

接口

import org.apache.ibatis.annotations.MapKey;

public interface UserMapper {

    // 指定的key必须是唯一的,否则重复的重复map的key会覆盖,如果查询的字段中没有唯一值,可以通过rowno来指定
    @MapKey("rowno")
    Map> selectTestData2();
}

	
    
        SELECT
	      @rowno := @rowno + 1 AS rowno,
	      t_user.email AS email,
	      t_user.avatar AS avatar
        FROM
	      t_user,
	      ( SELECT @rowno := 0 ) t
        ORDER BY
	      rowno DESC
    

调用

@Service
public class MapTest implements CommandLineRunner {

    @Autowired
    private UserMapper mapper;

    @Override
    public void run(String... args) throws Exception {

        Map> mapData1 = mapper.selectTestData2();
        System.out.println(mapData1);
    }
}

三. 方式3

接口

import org.apache.ibatis.annotations.MapKey;

public interface UserMapper {

    // 指定的key名称必须是User实体类中的属性
    @MapKey("id")
    Map selectTestData3();
}

    
    
        SELECT
          t_user.id as id,
          t_user.email as email,
          t_user.avatar as avatar
        FROM
          t_user
    

调用

@Service
public class MapTest implements CommandLineRunner {

    @Autowired
    private UserMapper mapper;

    @Override
    public void run(String... args) throws Exception {

        Map mapData2 = mapper.selectTestData3();
        Set> entries = mapData2.entrySet();
        for (Map.Entry entry : entries) {
            User user = entry.getValue();
            System.out.println(user);
        }
    }
}

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