SpringBoot集成Mybatis-plus

本节主要介绍如何在新项目中集成Mybatis-plus；从而完成对一个数据库表的增删查改操作。

创建一个Springboot工程

--- 此处略过

引入对应的依赖包

完整的pom.xml文件如下

<?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>2.3.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.hank</groupId>
    <artifactId>mybatisdemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>mybatisdemo</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-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <!-- mybatis -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.3.1</version>
        </dependency>
<!--        <dependency>-->
<!--            <groupId>com.alibaba</groupId>-->
<!--            <artifactId>druid</artifactId>-->
<!--            <version>1.1.20</version>-->
<!--        </dependency>-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

以上内容，与Mybatis-plus相关主要为以下部分

 <!-- mybatis -->
  <dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
  </dependency>
  <dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.3.1</version>
  </dependency>
  <!--        <dependency>-->
  <!--            <groupId>com.alibaba</groupId>-->
  <!--            <artifactId>druid</artifactId>-->
  <!--            <version>1.1.20</version>-->
  <!--        </dependency>-->

Mybatis-plus是基于Mybatis的一个增强插件，默认具备Mybatis的所有特性外加分页功能；

最后我们可以在项目结构中最终映入的Jar包资源，其中与Mybatis-plus相关的资源如下

(在IDEA工具中，通过File-->Project Structure...-->Modules-->选中自己的项目-->Dependencies)

从以上我们可以看到，虽然我们只在pom.xml中引入了mybatis-plus-boot-starter,版本为3.3.1,但是最终实际引入了其他的相关资源包。

\

编码部分

添加启动扫描注解

在项目启动类添加启动注解扫描;如果不在启动类配置，也可以在每个mapper上加上@Mapper注解

@SpringBootApplication
@MapperScan("com.hank.mybatisdemo.dao")
public class MybatisdemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(MybatisdemoApplication.class, args);
    }
}

编写实体类和Mapper类

此处以T_Temp为例;注意，这里接口类需要继承BaseMapper类，泛型为User实体对象

package com.hank.mybatisdemo.dao;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.hank.mybatisdemo.entity.User;

public interface UserMapper extends BaseMapper<User> {
}

User实体对象如下

package com.hank.mybatisdemo.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
@TableName(value = "T_Temp")
public class User {

    @TableId(value = "id",type= IdType.AUTO)
    Integer id;
    @TableField(value = "user_name")
    String userName;
    Integer age;
    String sex;
    String remark;
}

对应表的结构如下

/*Table structure for table `t_temp` */

DROP TABLE IF EXISTS `t_temp`;

CREATE TABLE `t_temp` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_name` varchar(30) DEFAULT NULL,
  `age` int(11) DEFAULT NULL,
  `sex` varchar(2) DEFAULT NULL,
  `remark` varchar(225) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=22 DEFAULT CHARSET=utf8mb4;

配置文件

spring:
  datasource:
#    type: com.alibaba.druid.pool.DruidDataSource
    url: jdbc:mysql://127.0.0.1:3306/btest?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
    username: root
    password: root
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.mysql.cj.jdbc.MysqlDataSource

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编写测试用例验证

@RunWith(SpringRunner.class)
@SpringBootTest
public class UserTest {
    @SuppressWarnings("SpringJavaInjectionPointsAutowiringInspection")
    @Autowired
    UserMapper userMapper;

    @Test
    public void testUser(){
        List<User> userList=userMapper.selectList(null);
        userList.forEach(System.out::println);
    }

    @Test
    public void testUser2(){
        for (int i = 0; i <10 ; i++) {
            User u=new User();
            u.setUserName("张三"+i);
            Random random = new Random();
            u.setAge(random.nextInt());
            u.setSex(i%2>1?"男":"女");
            int row=userMapper.insert(u);
            Assert.assertEquals(1, row);
        }
    }
}