1.mybatisplus的作用

主要是解决java对象和数据库表和字段的映射关联

2.mybatisplus使用流程

2.1pom.xml文件中增加依赖（点击右上角蓝色按钮下载依赖）

注意修改你的spinrtboot版本为2.7.6,不同版本的依赖版本也是不一样的

以下代码供复制

<!--mybatisPlus依赖-->
		<dependency>
			<groupId>com.baomidou</groupId>
			<artifactId>mybatis-plus-boot-starter</artifactId>
			<version>3.4.2</version>
		</dependency>
		<!--mysql依赖驱动-->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.47</version>
		</dependency>
		<!--数据库连接池druid-->
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid-spring-boot-starter</artifactId>
			<version>1.1.20</version>
		</dependency>

2.2navicat新建数据库，增加application.properties数据库配置

2.2.1 新建数据库，并建立一个user表

2.2.2application.properties文件增加内容

以下代码供复制

spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/mydb?useSSL=false
spring.datasource.username=root
spring.datasource.password=123456
mybatis-plus.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

2.3 启动类添加注解，增加mapper包操作数据库

2.3.1增加mapper包，并新建一个UserMapper接口interface操作用户表

UserMapper的内容

UserMapper内容供复制

package org.example.mybatisdemo.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Mapper;
import org.example.mybatisdemo.entity.User;


@Mapper
public interface UserMapper extends BaseMapper<User> {

}

2.3.2启动类增加注解，标识要扫描的mapper包

2.5添加实体类（类属性和建立的User表一致）

供参考代码

package org.example.mybatisdemo.entity;

public class User {
    private int id;
    private String username;
    private String password;
    private String birth;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getBirth() {
        return birth;
    }

    public void setBirth(String birth) {
        this.birth = birth;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", birth='" + birth + '\'' +
                '}';
    }
}

2.4添加控制器包，给前端提供接口

代码供复制

package org.example.mybatisdemo.controller;

import org.example.mybatisdemo.entity.User;
import org.example.mybatisdemo.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class UserController {

    @Autowired
    private UserMapper userMapper;
    @GetMapping("/user")
    public String query() {
        List<User> list = userMapper.selectList(null);
        System.out.println(list);
        return list.toString();
    }

    @PostMapping("/user")
    public String save(User user) {
        int i = userMapper.insert(user);
        if (i > 0) {
            return "插入成功";
        } else {
            return "插入失败";
        }

    }


}

3.浏览器访问测试

3.2浏览器测试

接口实现成功
3.2postman测试（插入成功）