MyBatis注解开发

MyBatis常用注解

将映射文件替换为注解：

public interface UserMapper {
 @Insert("insert into user value (...)")
 public  void save(User user);
 @Update("")
 public List<User> findAll();
}

其他delete，select等注解类似

之后将之前核心配置文件中的加载映射文件代码换成：

    <mappers>
<!--       指定接口所在包-->
        <package name="com.xxx.Mapper"/>
    </mappers>

复杂查询：

一对一：

方法一

@Insert("insert into user value (...)")
@Results({
        @Result(column = "oid",property = "id")
        @Result(column = "oid",property = "id")
        @Result(column = "oid",property = "id")
})
public  void save(User user);

方法二

@Select("select * from orders ")
@Results({
        @Result(column = "oid",property = "id"),
        @Result(column = "oid",property = "id"),
        @Result(column = "oid",property = "id"),
        @Result(
                property = "user",//要封装的属性名称
                column = "uid",//根据那个字段来查询另外一个表数据
                javaType = User.class,//要封装的实体类型
                //select属性代表那个接口方法获得数据，findById是我们写好的一个带select注解的接口方法用来查询id相同的
                one=@One(select = "com.xxx.mapper.UserMapper.findById")
        )
})
public  void save(User user);

一对多：

@Select("select * from user ")
@Results({
        @Result(id = true, column = "id", property = "id"),
        @Result(column = "oid", property = "id"),
        @Result(column = "oid", property = "id"),
        @Result(property = "orderList",
                column = "id",
                javaType = List.class,
                many = @Many(select = "com.xxx.mapper.findById")
        )
})
public  void save(User user);

多对多：

@Select("select * from user ")
@Results({
        @Result(id = true, column = "id", property = "id"),
        @Result(column = "username", property = "username"),
        @Result(column = "password", property = "password"),
        @Result(property = "roleList",
                column = "id",
                javaType = List.class,
                many = @Many(select = "com.xxx.mapper.findByUid")
        )
})
public  void save(User user);
@Select("select * from sys_user_role ur,sys_role r where ur.roleId=r.id And ur.userId=#{uid")
public  void findByUid(User user);