1.mybatis-plus 版本

<dependency>
     <groupId>com.github.jeffreyning</groupId>
     <artifactId>mybatisplus-plus</artifactId>
     <version>1.5.1-RELEASE</version>
</dependency>
<dependency>
     <groupId>com.baomidou</groupId>
     <artifactId>mybatis-plus-boot-starter</artifactId>
     <version>3.1.0</version>
 </dependency>
 <dependency>
     <groupId>com.baomidou</groupId>
     <artifactId>mybatis-plus-generator</artifactId>
     <version>3.1.0</version>
 </dependency>

2.实体类

@TableName("etl_job")
public class Job implements Serializable {

    private static final long serialVersionUID=1L;

    @MppMultiId // 复合主键
    private String etlSystem;

    @MppMultiId // 复合主键
    private String etlJob;
}

3.Mapper类和mapper.xml

public interface JobMapper extends MppBaseMapper<Job> {

}

 <resultMap id="BaseResultMap" type="com.dd.study.beans.Job">
        <id column="etl_system" property="etlSystem" />
        <id column="etl_job" property="etlJob" />
 </resultMap>

4.Server和ServiceImpl

 public interface JobService extends IMppService<Job> {
 }

@Service
public class JobServiceImpl extends MppServiceImpl<JobMapper, Job> implements JobService {
}

5.接下来就是正式应用复合主键相关的操作了

jobService.saveOrUpdateByMultiId(job);

6.想要启动复合主键，还要记得在启动类加上@EnableMPP。