MyBatisPlus快速入门

MyBatisPlus快速入门

官方网站
https://mp.baomidou.com/guide
慕课网视频
https://www.imooc.com/learn/1130 入门
https://www.imooc.com/learn/1171 进阶

1.引入依赖和springboot配置

2.实体类和数据库表

3.Mapper接口

4.Mapper映射文件(可选)

5.测试类

引入依赖和springboot配置

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.9.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
    <java.version>1.8</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>3.1.0</version>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/db1?userSSL=false&serverTimezone=GMT%2B8&characterEncoding=utf-8
    username: root
    password: root

实体类和数据库表

#创建用户表
#mysql> show collation;
#mysql> show collate;
#mysql> show charset;

drop database if exists mp_01; 
create database mp_01 character set utf8mb4 collate utf8mb4_general_ci;
use mp_01;

drop table if exists user;
CREATE TABLE user (
    id BIGINT(20) PRIMARY KEY NOT NULL COMMENT '主键',
    name VARCHAR(30) DEFAULT NULL COMMENT '姓名',
    age INT(11) DEFAULT NULL COMMENT '年龄',
    email VARCHAR(50) DEFAULT NULL COMMENT '邮箱',
    manager_id BIGINT(20) DEFAULT NULL COMMENT '直属上级id',
    create_time DATETIME DEFAULT NULL COMMENT '创建时间',
    CONSTRAINT manager_fk FOREIGN KEY (manager_id)
        REFERENCES user (id)
)  ENGINE=INNODB CHARSET=UTF8;

#初始化数据：
INSERT INTO user (id, name, age, email, manager_id
	, create_time)
VALUES (1087982257332887553, '大boss', 40, 'boss@baomidou.com', NULL
		, '2019-01-11 14:20:20'),
	(1088248166370832385, '王天风', 25, 'wtf@baomidou.com', 1087982257332887553
		, '2019-02-05 11:12:22'),
	(1088250446457389058, '李艺伟', 28, 'lyw@baomidou.com', 1088248166370832385
		, '2019-02-14 08:31:16'),
	(1094590409767661570, '张雨琪', 31, 'zjq@baomidou.com', 1088248166370832385
		, '2019-01-14 09:15:15'),
	(1094592041087729666, '刘红雨', 32, 'lhm@baomidou.com', 1088248166370832385
		, '2019-01-14 09:48:16');

package com.mp.mybatis01.entity;

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

import java.io.Serializable;
import java.time.LocalDateTime;

@Data
@TableName("mp_user")
public class User implements Serializable {
    @TableId
    private Long userId;
    @TableField("name")
    private String realName;
    private Integer age;
    private String email;
    private Long managerId;
    private LocalDateTime createTime;

    //不对应表中字段 1.静态字段 2.瞬时字段 3.@TableField(exist = false)
//    private transient String remark;

//    private static String remark;
//    public static String getRemark(){return remark;}
//    public static void setRemark(String remark){
//        User.remark = remark;
//    }

    @TableField(exist = false)
    private String remark;

}

Mapper接口

package com.mp.mybatis01.dao;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
//@Mapper标识MyBatis的Mapper接口，@MapperScan用于扫描MyBatis的Mapper接口
@Mapper
public interface UserMapper extends BaseMapper<User> {
}

测试类

package com.mp.mybatis01.dao;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.mp.mybatis01.entity.User;
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 java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

@RunWith(SpringRunner.class)
@SpringBootTest
public class UserMapperTest {
    @Autowired
    private UserMapper userMapper;

    @Test
    public void selectList(){
        List<User> users = userMapper.selectList(null);
        users.forEach(System.out::println);
    }

    //如果插入成功则返回自动生成的主键
    @Test
    public void insert(){
        User user = new User();
//        user.setId(1180761990619959297L);
//        user.setName("刘备");
        user.setRemark("这是备注");
        user.setRealName("刘备");
        user.setAge(25);
        int rows = userMapper.insert(user);
        System.out.println(rows);
        System.out.println(user);
    }

    @Test
    public void selectById(){
        User user = userMapper.selectById(1087982257332887553L);
        System.out.println(user);
    }

    @Test
    public void selectBatchIds(){
//        List<User> users = userMapper.selectBatchIds(null);

//        List<Long> idList = new ArrayList<>();
//        List<User> users = userMapper.selectBatchIds(idList);

        List<Long> idList = new ArrayList<>();
        idList.add(1087982257332887553L);
        idList.add(1088248166370832385L);
        idList.add(1088250446457389058L);
        List<User> users = userMapper.selectBatchIds(idList);
        users.forEach(System.out::println);
    }

    @Test
    public void selectByMap(){
        HashMap<String, Object> condition = new HashMap<>();
        condition.put("name", "刘备");
        condition.put("age", 25);
        List<User> users = userMapper.selectByMap(condition);
        users.forEach(System.out::println);
    }

    @Test
    public void selectList2(){
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("age", 25).likeLeft("name", "备");
        List<User> users = userMapper.selectList(queryWrapper);
        users.forEach(System.out::println);
    }

    @Test
    public void selectList3(){
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        queryWrapper =  queryWrapper.inSql("manager_id", "select user_id from mp_user where name like '%大%' ");
        List<User> users = userMapper.selectList(queryWrapper);
        users.forEach(System.out::println);
    }

    @Test
    public void selectList4(){
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        queryWrapper.nested(wq->wq.lt("age", 40).or().isNotNull("email")).likeRight("name", "王");
        List<User> users = userMapper.selectList(queryWrapper);
        users.forEach(System.out::println);
    }

    @Test
    public void selectList5(){
        QueryWrapper<User> queryWrapper = new QueryWrapper<>();
        queryWrapper.select("user_id", "realName").like("name", "刘备");
        List<User> users = userMapper.selectList(queryWrapper);
        users.forEach(System.out::println);
    }

}

Mapper映射文件

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl # 打印sql
  mapper-locations: classpath:mapper/*.xml #映射文件位置
  type-aliases-package: com.mp.mybatis01.entity #实体类别名

<?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.mp.mybatis01.dao.UserMapper">
    <select id="selectByName" resultType="User">
      select * from mp_user where name = #{name}
    </select>
</mapper>

package com.mp.mybatis01.dao;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.mp.mybatis01.entity.User;
import org.apache.ibatis.annotations.Select;

import java.util.List;

//@Mapper标识MyBatis的Mapper接口，@MapperScan用于扫描MyBatis的Mapper接口
@Mapper
public interface UserMapper extends BaseMapper<User> {

    List<User> selectByName(String name);

    @Select("select * from mp_user where age > #{age}")
    List<User> selectByAge(Integer age);
}

@RunWith(SpringRunner.class)
@SpringBootTest
public class UserMapperTest {
    @Autowired
    private UserMapper userMapper;
    @Test
    public void selectByName(){
        List<User> users = userMapper.selectByName("王天风");
        users.forEach(System.out::println);
    }

    @Test
    public void selectByAge(){
        List<User> users = userMapper.selectByAge(20);
        users.forEach(System.out::println);
    }
}