通用Mapper（二）创建具体Mapper接口与Mapper接口介绍

1、创建具体的Mapper接口

　　继承通用的Mapper<T>,必须指定泛型<T>，例如下面的例子：

/**
 *
 * 具体操作数据库的 Mapper接口，需要继承通用Mapper提供的核心接口 Mapper<T>
 *     泛型类型就是实体类的类型
 *
 */
public interface EmployeeMapper extends Mapper<Employee> {
　　//其他必须手写的接口
}

 　　一旦继承了Mapper<T>,继承的Mapper就拥有了Mapper<T>所有的通用方法。

2、Mapper<T> 里面有什么

　　　　Mapper<T> 的声明

@tk.mybatis.mapper.annotation.RegisterMapper
public interface Mapper<T> extends
        BaseMapper<T>,
        ExampleMapper<T>,
        RowBoundsMapper<T>,
        Marker {

}

　　（1）BaseMapper<T>

@tk.mybatis.mapper.annotation.RegisterMapper
public interface BaseMapper<T> extends
        BaseSelectMapper<T>,
        BaseInsertMapper<T>,
        BaseUpdateMapper<T>,
        BaseDeleteMapper<T> {

}

　　　　① BaseSelectMapper<T>：定义基本的查询操作

/**
 * 通用Mapper接口,基础查询
 *
 * @param <T> 不能为空
 * @author liuzh
 */
@RegisterMapper
public interface BaseSelectMapper<T> extends
        SelectOneMapper<T>,
        SelectMapper<T>,
        SelectAllMapper<T>,
        SelectCountMapper<T>,
        SelectByPrimaryKeyMapper<T>,
        ExistsWithPrimaryKeyMapper<T> {

}

@RegisterMapper
public interface SelectOneMapper<T> {

    /**
     * 根据实体中的属性进行查询，只能有一个返回值，有多个结果是抛出异常，查询条件使用等号
     *
     * @param record
     * @return
     */
    @SelectProvider(type = BaseSelectProvider.class, method = "dynamicSQL")
    T selectOne(T record);

}

@RegisterMapper
public interface SelectMapper<T> {

    /**
     * 根据实体中的属性值进行查询，查询条件使用等号
     *
     * @param record
     * @return
     */
    @SelectProvider(type = BaseSelectProvider.class, method = "dynamicSQL")
    List<T> select(T record);

}

@RegisterMapper
public interface SelectAllMapper<T> {

    /**
     * 查询全部结果
     *
     * @return
     */
    @SelectProvider(type = BaseSelectProvider.class, method = "dynamicSQL")
    List<T> selectAll();
}

@RegisterMapper
public interface SelectCountMapper<T> {

    /**
     * 根据实体中的属性查询总数，查询条件使用等号
     *
     * @param record
     * @return
     */
    @SelectProvider(type = BaseSelectProvider.class, method = "dynamicSQL")
    int selectCount(T record);

}

@RegisterMapper
public interface SelectByPrimaryKeyMapper<T> {

    /**
     * 根据主键字段进行查询，方法参数必须包含完整的主键属性，查询条件使用等号
     *
     * @param key
     * @return
     */
    @SelectProvider(type = BaseSelectProvider.class, method = "dynamicSQL")
    T selectByPrimaryKey(Object key);

}

@RegisterMapper
public interface ExistsWithPrimaryKeyMapper<T> {

    /**
     * 根据主键字段查询总数，方法参数必须包含完整的主键属性，查询条件使用等号
     *
     * @param key
     * @return
     */
    @SelectProvider(type = BaseSelectProvider.class, method = "dynamicSQL")
    boolean existsWithPrimaryKey(Object key);

}

　　　　② BaseInsertMapper<T>：定义基本的插入操作

/**
 * 通用Mapper接口,基础查询
 *
 * @param <T> 不能为空
 * @author liuzh
 */
@RegisterMapper
public interface BaseInsertMapper<T> extends
        InsertMapper<T>,
        InsertSelectiveMapper<T> {

}

@RegisterMapper
public interface InsertMapper<T> {

    /**
     * 保存一个实体，null的属性也会保存，不会使用数据库默认值
     *
     * @param record
     * @return
     */
    @InsertProvider(type = BaseInsertProvider.class, method = "dynamicSQL")
    int insert(T record);

}

@RegisterMapper
public interface InsertSelectiveMapper<T> {

    /**
     * 保存一个实体，null的属性不会保存，会使用数据库默认值
     *
     * @param record
     * @return
     */
    @InsertProvider(type = BaseInsertProvider.class, method = "dynamicSQL")
    int insertSelective(T record);

}

　　　　③ BaseUpdateMapper<T>：定义基本的更新操作

/**
 * 通用Mapper接口,基础查询
 *
 * @param <T> 不能为空
 * @author liuzh
 */
@RegisterMapper
public interface BaseUpdateMapper<T> extends
        UpdateByPrimaryKeyMapper<T>,
        UpdateByPrimaryKeySelectiveMapper<T> {

}

@RegisterMapper
public interface UpdateByPrimaryKeyMapper<T> {

    /**
     * 根据主键更新实体全部字段，null值会被更新
     *
     * @param record
     * @return
     */
    @UpdateProvider(type = BaseUpdateProvider.class, method = "dynamicSQL")
    int updateByPrimaryKey(T record);

}

@RegisterMapper
public interface UpdateByPrimaryKeySelectiveMapper<T> {

    /**
     * 根据主键更新属性不为null的值
     *
     * @param record
     * @return
     */
    @UpdateProvider(type = BaseUpdateProvider.class, method = "dynamicSQL")
    int updateByPrimaryKeySelective(T record);

}

　　　　④ BaseDeleteMapper<T>：定义基本的删除操作

/**
 * 通用Mapper接口,基础删除
 *
 * @param <T> 不能为空
 * @author liuzh
 */
@RegisterMapper
public interface BaseDeleteMapper<T> extends
        DeleteMapper<T>,
        DeleteByPrimaryKeyMapper<T> {

}

@RegisterMapper
public interface DeleteMapper<T> {

    /**
     * 根据实体属性作为条件进行删除，查询条件使用等号
     *
     * @param record
     * @return
     */
    @DeleteProvider(type = BaseDeleteProvider.class, method = "dynamicSQL")
    int delete(T record);

}

@RegisterMapper
public interface DeleteByPrimaryKeyMapper<T> {

    /**
     * 根据主键字段进行删除，方法参数必须包含完整的主键属性
     *
     * @param key
     * @return
     */
    @DeleteProvider(type = BaseDeleteProvider.class, method = "dynamicSQL")
    int deleteByPrimaryKey(Object key);

}

　　（2）ExampleMapper<T>

/**
 * 通用Mapper接口,Example查询
 *
 * @param <T> 不能为空
 * @author liuzh
 */
@tk.mybatis.mapper.annotation.RegisterMapper
public interface ExampleMapper<T> extends
        SelectByExampleMapper<T>,
        SelectOneByExampleMapper<T>,
        SelectCountByExampleMapper<T>,
        DeleteByExampleMapper<T>,
        UpdateByExampleMapper<T>,
        UpdateByExampleSelectiveMapper<T> {

}

　　　　① SelectByExampleMapper<T>

@tk.mybatis.mapper.annotation.RegisterMapper
public interface SelectByExampleMapper<T> {

    /**
     * 根据Example条件进行查询
     *
     * @param example
     * @return
     */
    @SelectProvider(type = ExampleProvider.class, method = "dynamicSQL")
    List<T> selectByExample(Object example);

}

　　　　② SelectOneByExampleMapper<T>

@tk.mybatis.mapper.annotation.RegisterMapper
public interface SelectOneByExampleMapper<T> {

    /**
     * 根据Example条件进行查询
     *
     * @param example
     * @return
     */
    @SelectProvider(type = ExampleProvider.class, method = "dynamicSQL")
    T selectOneByExample(Object example);

}

　　　　③ SelectCountByExampleMapper<T>

@tk.mybatis.mapper.annotation.RegisterMapper
public interface SelectCountByExampleMapper<T> {

    /**
     * 根据Example条件进行查询总数
     *
     * @param example
     * @return
     */
    @SelectProvider(type = ExampleProvider.class, method = "dynamicSQL")
    int selectCountByExample(Object example);

}

　　　　④ DeleteByExampleMapper<T>

@tk.mybatis.mapper.annotation.RegisterMapper
public interface DeleteByExampleMapper<T> {

    /**
     * 根据Example条件删除数据
     *
     * @param example
     * @return
     */
    @DeleteProvider(type = ExampleProvider.class, method = "dynamicSQL")
    int deleteByExample(Object example);

}

　　　　⑤ UpdateByExampleMapper<T>

@tk.mybatis.mapper.annotation.RegisterMapper
public interface UpdateByExampleMapper<T> {

    /**
     * 根据Example条件更新实体`record`包含的全部属性，null值会被更新
     *
     * @param record
     * @param example
     * @return
     */
    @UpdateProvider(type = ExampleProvider.class, method = "dynamicSQL")
    int updateByExample(@Param("record") T record, @Param("example") Object example);

}

　　　　⑥ UpdateByExampleSelectiveMapper<T>

@tk.mybatis.mapper.annotation.RegisterMapper
public interface UpdateByExampleSelectiveMapper<T> {

    /**
     * 根据Example条件更新实体`record`包含的不是null的属性值
     *
     * @param record
     * @param example
     * @return
     */
    @UpdateProvider(type = ExampleProvider.class, method = "dynamicSQL")
    int updateByExampleSelective(@Param("record") T record, @Param("example") Object example);

}

　　（3）RowBoundsMapper<T>

/**
 * 通用Mapper接口,带RowBounds参数的查询
 * <p/>
 * 配合分页插件PageHelper可以实现物理分页
 * <p/>
 * PageHelper - http://git.oschina.net/free/Mybatis_PageHelper
 *
 * @param <T> 不能为空
 * @author liuzh
 */
@tk.mybatis.mapper.annotation.RegisterMapper
public interface RowBoundsMapper<T> extends
        SelectByExampleRowBoundsMapper<T>,
        SelectRowBoundsMapper<T> {

}

　　　　① SelectByExampleRowBoundsMapper<T>

@tk.mybatis.mapper.annotation.RegisterMapper
public interface SelectByExampleRowBoundsMapper<T> {

    /**
     * 根据example条件和RowBounds进行分页查询
     *
     * @param example
     * @param rowBounds
     * @return
     */
    @SelectProvider(type = ExampleProvider.class, method = "dynamicSQL")
    List<T> selectByExampleAndRowBounds(Object example, RowBounds rowBounds);

}

　　　　② SelectRowBoundsMapper<T>

@tk.mybatis.mapper.annotation.RegisterMapper
public interface SelectRowBoundsMapper<T> {

    /**
     * 根据实体属性和RowBounds进行分页查询
     *
     * @param record
     * @param rowBounds
     * @return
     */
    @SelectProvider(type = BaseSelectProvider.class, method = "dynamicSQL")
    List<T> selectByRowBounds(T record, RowBounds rowBounds);

}

　　（4）Marker

/**
 * 标记接口，继承该接口的接口，在MapperScannerConfigurer#setMarkerInterface时，会自动注册到通用Mapper
 *
 * @author liuzh
 * @since 3.2.2
 */
public interface Marker {

}

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