SpringBoot入门：SpringBoot集成mybatis-plus

1、mybatis-plus简介

MyBatis-Plus （简称 MP）是一个 MyBatis 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。
官网：https://mp.baomidou.com/
github： https://github.com/baomidou/mybatis-plus

2、新建maven项目，引入maven依赖

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.3.RELEASE</version>
    <relativePath/>
</parent>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>3.4.2</version>
    </dependency>

    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.10</version>
    </dependency>

    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.0.29</version>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.8</version>
    </dependency>

    <dependency>
        <groupId>commons-collections</groupId>
        <artifactId>commons-collections</artifactId>
        <version>3.2.1</version>
    </dependency>

</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <fork>true</fork>
            </configuration>
        </plugin>
    </plugins>
</build>

3、resources下新增配置文件application.yml

内容如下：

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/mybatis?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&generateSimpleParameterMetadata=true
    username: root
    password: root
 
mybatis:
  #开启驼峰命名法
  configuration:
    map-underscore-to-camel-case: true
mybatis-plus:
  mapper-locations: classpath:mappers/*.xml
  # 实体扫描，多个package用逗号或者分号分隔
  type-aliases-package: cn.river.springboot.model   #自己的实体类地址
  configuration:
    # 这个配置会将执行的sql打印出来，在开发或测试的时候可以用
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

数据库脚本：

CREATE TABLE `tb_user` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键ID',
  `name` varchar(30) DEFAULT NULL COMMENT '姓名',
  `age` int(11) DEFAULT NULL COMMENT '年龄',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 
INSERT INTO `mybatis`.`tb_user` (`id`, `name`, `age`) VALUES ('1', 'Jone', '18');
INSERT INTO `mybatis`.`tb_user` (`id`, `name`, `age`) VALUES ('2', 'Jack', '20');
INSERT INTO `mybatis`.`tb_user` (`id`, `name`, `age`) VALUES ('3', 'Tom', '28');
INSERT INTO `mybatis`.`tb_user` (`id`, `name`, `age`) VALUES ('4', 'Sandy', '21');
INSERT INTO `mybatis`.`tb_user` (`id`, `name`, `age`) VALUES ('5', 'Billie', '24');
INSERT INTO `mybatis`.`tb_user` (`id`, `name`, `age`) VALUES ('6', 'jason', '30');
 

4、新增接口UserMapper.java

继承BaseMapper，内容如下：

public interface UserMapper extends BaseMapper<User> {
 
}

User.java

@Data
@TableName("tb_user")
@ToString
@NoArgsConstructor
@AllArgsConstructor
public class User implements Serializable {
    @TableId(value = "id", type = IdType.AUTO)
    private Integer id;
 
    @TableField("name")
    private String name;
 
    @TableField("age")
    private Integer age;
 
}

BaseMapper中默认已经实现了基本的数据库表CRUD功能，可以直接使用，比较方便。

如果不满足自己的需求，可以在UserMapper中自定义方法，可以使用注解@Select,@Insert,@Update,@Delete或者xml配置实现数据操作。

5、新增springboot启动类

加上@MapperScan注解，扫描Mapper文件

@SpringBootApplication
@MapperScan("cn.river.springboot.mapper")
public class MyBatisPlusApplication {
 
    public static void main(String[] args) {
        SpringApplication.run(MyBatisPlusApplication.class, args);
    }
 
}

6、新增JUnit单元测试类进行测试

@RunWith(SpringRunner.class)
@SpringBootTest
public class SampleTest {
 
    @Resource
    private UserMapper userMapper;
 
    @Test
    public void testSelect() {
        List<User> userList = userMapper.selectList(null);
        userList.forEach(System.out::println);
    }
}