@toc

1、初始化工程

使用Spring Initializer快速初始化一个Spring Boot工程

2、添加依赖

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.1</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.baomidou.mybatisplus</groupId>
    <artifactId>mybatisplus01</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mybatisplus01</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.3.1</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</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>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

3、数据库创建

在数据库中新建一张user表，结构如下：

数据库的Schema 脚本如下：

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
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');

4、配置

4.1 application.yml

在该文件中配置mysql数据源

# DataSource Config
spring:
  datasource:
    url: jdbc:mysql://localhost:3306/mp?&useSSL=false&serverTimezone=UTC&allowPublicKeyRetrieval=true
    username: root
    password: 123456
    driver-class-name: com.mysql.cj.jdbc.Driver
# mybatis-plus配置控制台打印sql语句:
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

4.2 配置

项目结构如下

在启动类上加入@MapperScan注解，扫描mapper文件夹，这里由于每个人的包结构不一样，你看着改下就行

5、编码

5.1 实体类User.java

package com.baomidou.mybatisplus.bean;

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

@Data
@TableName("user")
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

1、上面的@TableName是为了和数据库中的user表对应
2、用lombok来简化代码

5.2 编写Mapper类UserMapper.java

package com.baomidou.mybatisplus.mapper;

import com.baomidou.mybatisplus.bean.User;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;

public interface UserMapper extends BaseMapper<User> {
}

6、测试

SpringBoot的测试类

package com.baomidou.mybatisplus;

import com.baomidou.mybatisplus.bean.Employee;
import com.baomidou.mybatisplus.bean.User;
import com.baomidou.mybatisplus.mapper.EmployeeMapper;
import com.baomidou.mybatisplus.mapper.UserMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.util.Assert;

import java.util.List;

@SpringBootTest
class Mybatisplus01ApplicationTests {

    @Autowired
    private UserMapper userMapper;
    @Autowired
    private EmployeeMapper employeeMapper;

    @Test
    void contextLoads() {
    }
    @Test
    public void testSelect(){
        System.out.println("----selectAll method test----");
        List<User> userList=userMapper.selectList(null);
        userList.forEach(System.out::println);
    }
}

执行之后，查看控制台输出

数据库中的数据

可以看到，mybatisplus确实强大，我一句sql语句都没写，数据就都查出来了。

7、小结

通过以上几个简单的步骤，我们就实现了 User 表的 CRUD 功能，甚至连 XML 文件都不用编写！

从以上步骤中，我们可以看到集成MyBatis-Plus非常的简单，只需要引入 starter 工程，并配置 mapper 扫描路径即可。