[Java知识库]lombok中的@Data注解与MyBatis的懒加载机制冲突解决

使用@Data注解与mybatis的懒加载机制实现一对一关系查询时，发现怎么配置都无效，就是一下都查出来了，根本没有懒加载

1.application.yml配置文件配置如下：

# mybatis 配置内容
mybatis-plus:
  #config-location: classpath:mybatis-config.xml # 配置 MyBatis 配置文件路径
  mapper-locations: classpath:mapper/*.xml # 配置 Mapper XML 地址
  type-aliases-package: com.steven.springboot.datasource.model # 配置数据库实体包路径
  configuration:
    map-underscore-to-camel-case: true
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
    lazy-loading-enabled: true
    aggressive-lazy-loading: false
    lazyLoadTriggerMethods:

2.实体类user.java

package com.steven.springboot.datasource.model;

import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;
@Data
@TableName("users")
public class UserDO {

    /**
     * 用户编号
     */
    private Integer id;
    /**
     * 账号
     */
    private String username;

    /**
     * 密码
     */
    private String password;

    private int did;

    private DeptDO deptDO;
}

3.实体类DeptDO.java

package com.steven.springboot.datasource.model;

import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

import java.util.List;

/**
 * @author Steven
 * @version 1.0
 * @date 2022/2/25 10:53
 * @description
 */
@Data
@TableName("dept")
public class DeptDO {
    private Integer id;
    private String name;
    private List<UserDO> userDOList;
}

4.映射文件UserMapper.xml

<?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="com.steven.springboot.datasource.mapper.UserMapper">
    <resultMap id="getUserAndDeptStep" type="UserDO">
        <id property="id" column="id"/>
        <result property="username" column="username"/>
        <result property="password" column="password"/>
        <result property="did" column="did"/>
        <association property="deptDO" select="com.steven.springboot.datasource.mapper.DeptMapper.getDeptByStep" column="did"/>
    </resultMap>
    <select id="selectUserAndDeptStep" resultMap="getUserAndDeptStep">
        select * from users where username like concat(#{username},"%") and password=#{password}
    </select>
</mapper>

5.映射文件DeptMapper.xml

<?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="com.steven.springboot.datasource.mapper.DeptMapper">
    <select id="getDeptByStep" resultType="DeptDO">
        select * from dept where id=#{id}
    </select>
</mapper>

6.测试类UserTests.java

package com.steven.springboot.datasource;
import com.steven.springboot.datasource.mapper.UserMapper;
import com.steven.springboot.datasource.model.UserDO;
import 
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import javax.annotation.Resource;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@RunWith(SpringRunner.class)
@SpringBootTest(classes = SpringbootDataSourceApplication.class)
public class UserTests {

	@Resource
	UserMapper userMapper;
	@Test
	public void getUserAndDeptByStep() {
		UserDO userDO=new UserDO();
		userDO.setUsername("张希");
		userDO.setPassword("123456");
		List<UserDO> userDOList = userMapper.selectUserAndDeptStep(userDO);
		System.out.println(userDOList);
	}
}

所以解决方案就是两种

1. 使用@Data同时再重写一遍toString()方法
2. 不用toString的话，就把@Data拆开