本篇内容主要讲解“Mybatis如何返回Map数据”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“Mybatis如何返回Map数据”吧!
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public interface UserMapper {
List<Map<String, String>> selectTestData1();
}<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="xxx.mapper.UserMapper">
<select id="selectTestData1" resultType="java.util.Map">
SELECT
t_user.id as id,
t_user.email as email,
t_user.avatar as avatar
FROM
t_user
</select>
</mapper>@Service
public class MapTest implements CommandLineRunner {
@Autowired
private UserMapper mapper;
@Override
public void run(String... args) throws Exception {
List<Map<String, String>> listData1 = mapper.selectTestData1();
for (Map<String, String> map : listData1) {
System.out.println(map);
}
}
}
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<String, Map<String,String>> selectTestData2();
}<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="xxx.mapper.UserMapper">
<!--
❗❗❗由于mysql没有oracle中的ROWNUM功能,因此只能通过下面的方式进行模拟
-->
<select id="selectTestData2" resultType="java.util.Map">
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
</select>
</mapper>@Service
public class MapTest implements CommandLineRunner {
@Autowired
private UserMapper mapper;
@Override
public void run(String... args) throws Exception {
Map<String, Map<String, String>> mapData1 = mapper.selectTestData2();
System.out.println(mapData1);
}
}
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<String, User> selectTestData3();
}<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="xxx.mapper.UserMapper">
<!--由于最终是把数据封装到User实体类中,所以返回值的数据类型是User而不是Map-->
<select id="selectTestData3" resultType="com.example.demo.transactionCom.entity.User">
SELECT
t_user.id as id,
t_user.email as email,
t_user.avatar as avatar
FROM
t_user
</select>
</mapper>@Service
public class MapTest implements CommandLineRunner {
@Autowired
private UserMapper mapper;
@Override
public void run(String... args) throws Exception {
Map<String, User> mapData2 = mapper.selectTestData3();
Set<Map.Entry<String, User>> entries = mapData2.entrySet();
for (Map.Entry<String, User> entry : entries) {
User user = entry.getValue();
System.out.println(user);
}
}
}
到此，相信大家对“Mybatis如何返回Map数据”有了更深的了解，不妨来实际操作一番吧！这里是亿速云网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！
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