MybatisPlus的快速开始

开始前的准备

1. jdk和编译器以及maven什么就不说了
2. 准备数据，这里用的是官方快速开始教程中提供的表

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)
);

DELETE FROM user;

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]');

快速开始

1. 创建SpringBoot工程
2. 引入相关依赖,注意的是如果导入了mybatisPlus的依赖后就不引入mybatis的依赖了，如果同时导入这两个以来的话依赖关系可能会出问题。

<dependency>
			<groupId>org.springframework.bootgroupId>
			<artifactId>spring-boot-starter-jdbcartifactId>
		dependency>
		<dependency>
			<groupId>org.springframework.bootgroupId>
			<artifactId>spring-boot-starter-webartifactId>
		dependency>

		<dependency>
			<groupId>mysqlgroupId>
			<artifactId>mysql-connector-javaartifactId>
			<scope>runtimescope>
		dependency>
		<dependency>
			<groupId>org.springframework.bootgroupId>
			<artifactId>spring-boot-starter-testartifactId>
			<scope>testscope>
			<exclusions>
				<exclusion>
					<groupId>org.junit.vintagegroupId>
					<artifactId>junit-vintage-engineartifactId>
				exclusion>
			exclusions>
		dependency>

        <dependency>
            <groupId>org.projectlombokgroupId>
            <artifactId>lombokartifactId>
            <optional>trueoptional>
        dependency>
        <dependency>
            <groupId>com.baomidougroupId>
            <artifactId>mybatis-plus-boot-starterartifactId>
            <version>3.0.5version>
        dependency>

3. 实体类的创建

package com.pning.pojo;

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

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
     
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

4. 配置文件

  Spring:
    datasource:
      username: root
      password: 123456
      driver-class-name: com.mysql.cj.jdbc.Driver
      url: jdbc:mysql://120.0.0.1:3306/mybatisplus?useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT%2b8

5. mapper文件的创建

package com.pning.mapper

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

@Repository
public interface UserMapper extends BaseMapper<User> {
     
}

5. 启动器添加扫描器

@MapperScan("com.pning.mapper")
@SpringBootApplication
public class MybatisplusApplication {
     
    public static void main(String[] args) {
     
        SpringApplication.run(MybatisplusApplication.class, args);
    }

}

6. 运行测试类

package com.pning;

import com.pning.mapper.UserMapper;
import com.pning.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 {
     
    @Autowired
    private UserMapper userMapper;

    @Test
    public void selectList(){
     
        List<User> userList = userMapper.selectList(null);//里面的参数就是一个wrapper，也就是条件构造器，如果不用的话写为null即可
        userList.forEach(System.out::println);
    }

}