扩展tk.mybatis的流式查询功能实现

扩展tk.mybatis的流式查询功能实现

mybatis查询默认是一次获取全部， 有时候需要查询上万上百万数据时，如果一次性读取到内存中，会容易导致OOM问题。这时候需要采用流式查询。以下扩展了tk.mybatis的流式查询功能。 直接上干货：

@Options注解是关键

import org.apache.ibatis.annotations.Options;

import org.apache.ibatis.annotations.SelectProvider;

import org.apache.ibatis.mapping.ResultSetType;

import org.apache.ibatis.session.ResultHandler;

/**

* 通用Mapper接口,流式查询

*

* @param 不能为空

* @author sunchangtan

*/

@tk.mybatis.mapper.annotation.RegisterMapper

public interface SelectStreamByExampleMapper {

/**

* 根据example条件和RowBounds进行流式查询

*

* @param example

* @return

*/

@Options(resultSetType = ResultSetType.FORWARD_ONLY, fetchSize = 1000)

@SelectProvider(type = StreamExampleProvider.class, method = "dynamicSQL")

void selectStreamByExampleMapper(Object example, ResultHandler resultHandler);

}

带RowBounds的流式查询

import org.apache.ibatis.annotations.Options;

import org.apache.ibatis.annotations.SelectProvider;

import org.apache.ibatis.mapping.ResultSetType;

import org.apache.ibatis.session.ResultHandler;

import org.apache.ibatis.session.RowBounds;

/**

* 通用Mapper接口,流式查询

*

* @param 不能为空

* @author sunchangtan

*/

@tk.mybatis.mapper.annotation.RegisterMapper

public interface SelectStreamByExampleRowBoundsMapper

/**

* 根据example条件和RowBounds进行流式查询

*

* @param example

* @return

*/

@Options(resultSetType = ResultSetType.FORWARD_ONLY, fetchSize = 1000)

@SelectProvider(type = StreamExampleProvider.class, method = "dynamicSQL")

void selectStreamByExampleRowBoundsMapper(Object example, RowBounds rowBounds, ResultHandler resultHandler);

}

流式ExampleProvider

import org.apache.ibatis.mapping.MappedStatement;

import tk.mybatis.mapper.mapperhelper.MapperHelper;

import tk.mybatis.mapper.provider.ExampleProvider;

/**

* 流式查询的SqlProvider

* @author sunchangtan

*/

public class StreamExampleProvider extends ExampleProvider {

public StreamExampleProvider(Class> mapperClass, MapperHelper mapperHelper) {

super(mapperClass, mapperHelper);

}

/**

* 根据Example流式查询

*

* @param ms

* @return

*/

public String selectStreamByExampleMapper(MappedStatement ms) {

return this.selectByExample(ms);

}

/**

* 根据Example和RowBounds流式查询

* @param ms

* @return

*/

public String selectStreamByExampleRowBoundsMapper(MappedStatement ms) {

return this.selectByExample(ms);

}

}

将SelectStreamByExampleMapper和SelectStreamByExampleRowBoundsMapper组合成一个接口

/**

* 流式查询接口

* @param

* @author sunchangtan

*/

@tk.mybatis.mapper.annotation.RegisterMapper

public interface StreamaRlnjvqmMapper extends

SelectStreamByExampleMapper,

SelectStreamByExampleRowBoundsMapper {

}

在BaseMapper中加http://入StreamMapper

/**

* Mapper的基类

* @author sunchangtan

* @param

*/

public interface BaseMapper extends Mapper, mysqlMapper, StreamMapper {

}

使用例子：

this.userMapper.selectStreamByExampleRowBoundsMapper(example, new RowBounds(0, 1), resultContext -> {

User user= (User) resultContext.getResultObject();

System.out.println(user);

});

this.userMapper.selectStreamByExampleMapper(example, resultContext -> {

User user= (User) resultContext.getResultObject();

System.out.println(User);

});

/**

* 根据example条件和RowBounds进行流式查询

*

* @param example

* @return

*/

@Options(resultSetType = ResultSetType.FORWARD_ONLY, fetchSize = 1000)

@SelectProvider(type = StreamExampleProvider.class, method = "dynamicSQL")

void selectStreamByExampleRowBoundsMapper(Object example, RowBounds rowBounds, ResultHandler resultHandler);

}

流式ExampleProvider

import org.apache.ibatis.mapping.MappedStatement;

import tk.mybatis.mapper.mapperhelper.MapperHelper;

import tk.mybatis.mapper.provider.ExampleProvider;

/**

* 流式查询的SqlProvider

* @author sunchangtan

*/

public class StreamExampleProvider extends ExampleProvider {

public StreamExampleProvider(Class> mapperClass, MapperHelper mapperHelper) {

super(mapperClass, mapperHelper);

}

/**

* 根据Example流式查询

*

* @param ms

* @return

*/

public String selectStreamByExampleMapper(MappedStatement ms) {

return this.selectByExample(ms);

}

/**

* 根据Example和RowBounds流式查询

* @param ms

* @return

*/

public String selectStreamByExampleRowBoundsMapper(MappedStatement ms) {

return this.selectByExample(ms);

}

}

将SelectStreamByExampleMapper和SelectStreamByExampleRowBoundsMapper组合成一个接口

/**

* 流式查询接口

* @param

* @author sunchangtan

*/

@tk.mybatis.mapper.annotation.RegisterMapper

public interface StreamaRlnjvqmMapper extends

SelectStreamByExampleMapper,

SelectStreamByExampleRowBoundsMapper {

}

在BaseMapper中加http://入StreamMapper

/**

* Mapper的基类

* @author sunchangtan

* @param

*/

public interface BaseMapper extends Mapper, mysqlMapper, StreamMapper {

}

使用例子：

this.userMapper.selectStreamByExampleRowBoundsMapper(example, new RowBounds(0, 1), resultContext -> {

User user= (User) resultContext.getResultObject();

System.out.println(user);

});

this.userMapper.selectStreamByExampleMapper(example, resultContext -> {

User user= (User) resultContext.getResultObject();

System.out.println(User);

});

版权声明：本文内容由网络用户投稿，版权归原作者所有，本站不拥有其著作权，亦不承担相应法律责任。如果您发现本站中有涉嫌抄袭或描述失实的内容，请联系我们jiasou666@gmail.com 处理，核实后本网站将在24小时内删除侵权内容。