mybatis-plus

官网

MyBatis-Plus (opens new window)（简称 MP）是一个 MyBatis (opens new window)的增强工具，在 MyBatis 的基础上只做增强不做改变，为简化开发、提高效率而生。

一 快速入门

1.1 建库

1.2 建表

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)
);

1.3 插入语句

DELETE FROM user;

INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, 'test1@baomidou.com'),
(2, 'Jack', 20, 'test2@baomidou.com'),
(3, 'Tom', 28, 'test3@baomidou.com'),
(4, 'Sandy', 21, 'test4@baomidou.com'),
(5, 'Billie', 24, 'test5@baomidou.com');

1.4 初始化工程

创建一个空的 Spring Boot 工程。

1.5 添加依赖

<dependencies>
        <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>

        <!--1.数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <!--2.lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <!--3.mybatis-plus  版本很重要3.0.5-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.0.5</version>
        </dependency>
        <!--4.h2 H2是一个开源的、纯Java实现的关系型数据库。-->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

    </dependencies>

1.6 连接数据库配置

maven下载的时mysql8的依赖，因此配置是按照mysql8的驱动配置的，但是不影响驱动mysql5的数据库

#数据库连接配置
spring.datasource.username=root
spring.datasource.password=root
#mysql5~8 驱动不同driver-class-name     8需要增加时区的配置serverTimezone=UTC
#useSSL=false 安全连接
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis_plus?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

1.7 编写实体类

package com.qiaob.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;
}

1.8 编写实体类对应接口

(记得继承时泛型要绑定，不然报错org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.qiaob.mapper.UserMapper.selectList)

package com.qiaob.mapper;

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

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

1.9 在主启动类添加@MapperScan注解

@SpringBootApplication
//扫描mapper包下的所有接口
@MapperScan("com.qiaob.mapper")
public class MpApplication {

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

}

1.10 进行Test测试

package com.qiaob;

import com.qiaob.mapper.UserMapper;
import com.qiaob.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 MpApplicationTests {
    @Autowired
   private UserMapper userMapper;
    @Test
    void contextLoads() {
        List<User> list = userMapper.selectList(null);
        for (User user : list) {
            System.out.println(user);
        }
    }

}