Mybatisplus-plus 1.3.1新增在service层操作复合主键进行增删改查相关操作的功能。

**从中央库引入jar**
````
    <dependency>
        <groupId>com.github.jeffreyning</groupId>
        <artifactId>mybatisplus-plus</artifactId>
        <version>1.3.1-RELEASE</version>
    </dependency>
````

在实例类成员变量上使用@MppMultiId表明联合主键
````
@TableName("test07")
public class Test07Entity {
    @MppMultiId
    @TableField(value = "k1")
    private Integer k1;

    @MppMultiId
    @TableField(value = "k2")
    private String k2;
    
    @TableField(value = "col1")
    private String col1;
    @TableField(value = "col2")
    private String col2;    
````

mapper需要继承MppBaseMapper
````
@Mapper
public interface Test07Mapper extends MppBaseMapper<Test07Entity> {
}
````

````
service层继承IMppService
````
public interface Test07Service extends IMppService<Test07Entity> {
}
@Service
public class Test07ServiceImpl extends ServiceImpl<Test07Mapper, Test07Entity> implements Test07Service {
}
````

在service层调用多主键操作
````
    public void testMultiIdService(){
        //id
        Test07Entity idEntity=new Test07Entity();
        idEntity.setK1(1);
        idEntity.setK2("111");
        //del

        test07Service.deleteByMultiId(idEntity);
        //add
        test07Service.save(idEntity);
        //query
        Test07Entity retEntity=test07Service.selectByMultiId(idEntity);
        retEntity.setCol1("xxxx");
        //update
        test07Mapper.updateByMultiId(retEntity);
    }
````