mybatis-plus的使用

gfu

发布于 2019-10-22 22:51:24

9460

发布于 2019-10-22 22:51:24

文章被收录于专栏：gfugfu

mybatis-plus是对mybatis的扩展，非常的好用，不管对单表还是多表都提供了分页的功能，后续也有分页的例子，而且针对单表的增删改查只需要继承BaseMapper，再根据QueryWrapper和UpdateWrapper就可以简单的对单表进行操作了，最后有一个简单的图解供参考。

继承baseMapper
写一个DO
单测

多表的分页只需要在Mapper里的方法中传入Page这个对象就可以自动分页了，mybatis-plus是基于mybatis，也要引入对应的包。本项目是基于gradle构建的。用到的jar包，如果是springboot项目：

    // https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter
    compile group: 'org.mybatis.spring.boot', name: 'mybatis-spring-boot-starter', version: '2.1.0'

    // https://mvnrepository.com/artifact/com.baomidou/mybatis-plus-boot-starter
    compile group: 'com.baomidou', name: 'mybatis-plus-boot-starter', version: '3.2.0'

如果单独引包：

    // https://mvnrepository.com/artifact/org.mybatis/mybatis
    compile group: 'org.mybatis', name: 'mybatis', version: '3.5.2'

    // https://mvnrepository.com/artifact/com.baomidou/mybatis-plus
    compile group: 'com.baomidou', name: 'mybatis-plus', version: '3.2.0'

1.写一个mapper，继承BaseMapper

package org.sjframework.learn.mybatis.plus;

import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.sjframework.learn.mybatis.UserDO;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;

/**
 * mybatis-plus
 *
 * @author 719383495@qq.com |719383495qq@gmail.com |gfu
 * @date 2019/10/18
 */
@Mapper
public interface UserDaoPlus extends BaseMapper<UserDO> {

}

2.单表属性

package org.sjframework.learn.mybatis;

import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableName;
import com.baomidou.mybatisplus.core.conditions.Wrapper;
import com.baomidou.mybatisplus.core.conditions.segments.MergeSegments;

/**
 * user dao
 *
 * @author 719383495@qq.com |719383495qq@gmail.com |gfu
 * @date 2019/10/18
 */
@TableName("t_user")
public class UserDO {

    private String userId;

    private String leader;

    public String getUserId() {
        return userId;
    }

    public void setUserId(String userId) {
        this.userId = userId;
    }

    public String getLeader() {
        return leader;
    }

    public void setLeader(String leader) {
        this.leader = leader;
    }

    @Override
    public String toString() {
        return "UserDO{" +
                "userId='" + userId + '\'' +
                ", leader='" + leader + '\'' +
                '}';
    }
}

3.用mybatis-plus给的包装类，操作单表。会写下面的一种，其他的语句举一反三。

package org.sjframework.learn.mybatis;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.sjframework.learn.mybatis.plus.UserDaoPlus;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import java.util.List;

/**
 * mybatis test
 *
 * @author 123456789@qq.com |123456789@gmail.com |gfu
 * @date 2019/10/17
 */
@RunWith(SpringRunner.class)
@SpringBootTest
public class MybatisPlusTest {

    @Autowired
    UserDaoPlus userDaoPlus;

    @Test
    public void loadContext() {
        Page<UserDO> page = new Page<>(2, 100);
        QueryWrapper<UserDO> wrapper = new QueryWrapper<>();

        // 分页
        IPage<UserDO> mapIPage = userDaoPlus.selectPage(page, wrapper);
        System.out.println(mapIPage.getRecords());
        List<UserDO> records = mapIPage.getRecords();
        records.forEach(i -> System.out.println(i));

        // 筛选
        wrapper.eq("user_id", "U00003");
        List<UserDO> res = userDaoPlus.selectList(wrapper);
        System.out.println(res);
    }
}