MyBatis-Plus（基于springboot）直接上手

数据库文件（mybatis_plus 数据库名字）

整体的工程结构

雪花算法，自动生成id传送门

乐观锁讲解传送门，点击！！！

自动填充处理 点击！！

分页查询操作

DROP TABLE IF EXISTS user;
CREATE TABLE user
(
id BIGINT(20) NOT NULL COMMENT '主键ID',
name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
age INT(11) NULL DEFAULT NULL COMMENT '年龄',
email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
PRIMARY KEY (id)
);INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, '[email protected]'),
(2, 'Jack', 20, '[email protected]'),
(3, 'Tom', 28, '[email protected]'),
(4, 'Sandy', 21, '[email protected]'),
(5, 'Billie', 24, '[email protected]');

pom.xml文件 需要添加的

  <!-- 数据库驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!-- lombok -->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <!-- mybatis-plus -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.0.5</version>
        </dependency>

1.这里UserMapper，不需要在配置繁琐的xml文件

package com.xyj.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.xyj.pojo.User;
import org.springframework.stereotype.Repository;

/**
 * @author xyj
 * @date 2020/4/24 -10:20
 */
@Repository
public interface UserMapper extends BaseMapper<User>{


}

2.pojo层里的User，与数据库对应

package com.xyj.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
 * @author xyj
 * @date 2020/4/24 -10:17
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {

    private Long id;
    private String name;
    private Integer age;
    private String email;



}

3.这里注意MybatisPlusApplication这里需要添加扫描mapper文件
@MapperScan(“com.xyj.mapper”)对应你的包位置

package com.xyj;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
//扫描mapper文件夹
@MapperScan("com.xyj.mapper")
@SpringBootApplication
public class MybatisPlusApplication {

    public static void main(String[] args) {
        SpringApplication.run(MybatisPlusApplication.class, args);
    }

}

4.application.properties的相关配置，与之前没有什么不同

spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis_plus?useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

5.测试一下在MybatisPlusApplicationTests

package com.xyj;

import com.xyj.mapper.UserMapper;
import com.xyj.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest
class MybatisPlusApplicationTests {
    //继承basemapper，所有方法来自父类
    @Autowired
    private UserMapper userMapper;

    @Test
    void contextLoads() {
        //查询全部
        List<User> users = userMapper.selectList(null);
        users.forEach(System.out::println);
    }

}

只需几步就可以完成CRUD操作

添加操作

  @Test
    public void testInsert(){
        User user = new User();
        user.setName("xyj");
        user.setAge(18);
        user.setEmail("[email protected]");
        int result = userMapper.insert(user);//帮我们自动生成id
        System.out.println(result);
        System.out.println(user);

        System.out.println(user.getId());

    }

更新操作

//通过条件自动拼接动态sql
    @Test
    public void testUpdate(){
        User user = new User();
        user.setId( 5L);
        user.setAge(60);
        user.setName("青青草原");
        user.setEmail("[email protected]");
        int result = userMapper.updateById(user);
        System.out.println(result);
    }

条件查询

//单个查询
 @Test
    public void testSelectById(){
        User user = userMapper.selectById(1L);
        System.out.println(user);
    }
    //批量查询
    @Test
    public void testSelectById1(){
        List<User> user = userMapper.selectBatchIds(Arrays.asList(1, 2, 3));
        user.forEach(System.out::println);
    }
    //条件查询  map
    @Test
    public void testSelectByBatchIds(){
        HashMap<String, Object> hashmap = new HashMap<>();
        //自定义查询,这里可以根据不同条件设置
        hashmap.put("name","xyj");
        hashmap.put("age",18);

        List<User> user = userMapper.selectByMap(hashmap);
        user.forEach(System.out::println);

    }

删除操作

 //删除
    @Test
    public void testDelete(){
        int i = userMapper.deleteById(5L);

    }
    // 通过id批量删除
    @Test
    public void testDeleteBatchId(){
        userMapper.deleteBatchIds(Arrays.asList(1L,2L));
    }

    // 通过map删除
    @Test
    public void testDeleteMap(){
        HashMap<String, Object> map = new HashMap<>();
        map.put("name","xyj");
        userMapper.deleteByMap(map);
    }