Mybatis批量更新对象数据的两种实现方式

import lombok.Data;
import java.io.Serializable;

@Data
public class User implements Serializable {
    
    private String id;

    private String username;

    private String password;
}

@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserMapper userMapper;

    /**
     * 根据ID查询用户
     * @param id
     * @return
     */
    @GetMapping("/getUser/{id}")
    public String getUser(@PathVariable("id") String id){
        return userMapper.getUser(id).toString();
    }
}

import com.hezy.pojo.User;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface UserMapper {

    User getUser(String id);
}

    @GetMapping("/updateUser")
    public void updateUser(){
        ArrayList<User> users = new ArrayList<>();

        User user1 = new User();
        user1.setId("1");
        user1.setUsername("zhangsan_fix");

        User user2 = new User();
        user2.setId("2");
        user2.setUsername("lisi_fix");
        user2.setPassword("654321_fix");

        users.add(user1);
        users.add(user2);
        userMapper.updateUser(users);
    }

    <update id="updateUser">
        <foreach collection="users" item="user" separator=";">
            update tb_user
            <set>
                <if test="user.username != null and user.username != ''">
                    username = #{user.username},
                </if>
                <if test="user.password != null and user.password != ''">
                    password = #{user.password}
                </if>
            </set>
            where id = #{user.id}
        </foreach>
    </update>

	<update id="updateUser">
	    update tb_user
	    set
	    
	    username = case
	    <foreach collection="users" item="user">
	        when id = #{user.id}
	        <choose>
	            <when test="user.username != null and user.username != ''">then #{user.username}</when>
	            <otherwise>then username</otherwise>
	        </choose>
	    </foreach>
	    end,
	
	    password = case
	    <foreach collection="users" item="user">
	        when id = #{user.id}
	        <choose>
	            <when test="user.password != null and user.password != ''">then #{user.password}</when>
	            <otherwise>then password</otherwise>
	        </choose>
	    </foreach>
	    end
	
	    where
	    <foreach collection="users" item="user" separator="or">
	        id = #{user.id}
	    </foreach>
	</update>

	update tb_user
	set
	    username = case
	                   when id = '1' then 'zhangsan_fix'
	                   when id = '2' then 'lisi_fix'
	    end,
	
	    password = case
	                   when id = '1' then password
	                   when id = '2' then '654321_fix'
	    end
	where id = '1'
	   or id = '2';