所谓浮躁，也就是时时刻刻，希望以最短的时间，博取最多的存在感、优越感和自我认同。——张佳玮
分享一个mybatis流式查询
用法很简单：
package com.ruben; import com.ruben.mapper.UserMapper; import com.ruben.pojo.po.UserPO; import lombok.SneakyThrows; import org.apache.ibatis.cursor.Cursor; import org.apache.ibatis.session.RowBounds; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.junit.jupiter.api.Assertions; import org.junit.jupiter.api.Test; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.transaction.annotation.Transactional; import org.springframework.transaction.support.TransactionTemplate; import javax.annotation.Resource; import java.io.IOException; import java.util.stream.StreamSupport; @SpringBootTest class SimpleMybatisApplicationTests { @Resource private SqlSessionFactory sqlSessionFactory; @Resource private TransactionTemplate transactionTemplate; @Resource private UserMapper userMapper; @Test @SneakyThrows void sqlSessionWay() { Assertions.assertAll(() -> { try (SqlSession session = sqlSessionFactory.openSession(); Cursor<UserPO> userCursor = session.getMapper(UserMapper.class).selectPageCursor(new RowBounds(0, 5))) { StreamSupport.stream(userCursor.spliterator(), true).forEach(System.out::println); } }); } @Test void transactionTemplateWay() { Assertions.assertAll(() -> transactionTemplate.executeWithoutResult(transactionStatus -> { try (Cursor<UserPO> userCursor = userMapper.selectPageCursor(new RowBounds(0, 5))) { StreamSupport.stream(userCursor.spliterator(), true).forEach(System.out::println); } catch (IOException e) { throw new RuntimeException(e); } })); } @Test @Transactional void transactionalWay() { Assertions.assertAll(() -> { try (Cursor<UserPO> userCursor = userMapper.selectPageCursor(new RowBounds(0, 5))) { StreamSupport.stream(userCursor.spliterator(), true).forEach(System.out::println); } catch (IOException e) { throw new RuntimeException(e); } }); } }
注意这里返回的Cursor需要关闭，可以用
StreamSupport.stream(userCursor.spliterator(), false);
将其转换为Stream流
Mapper：
package com.ruben.mapper; import com.ruben.pojo.po.UserPO; import org.apache.ibatis.annotations.Mapper; import org.apache.ibatis.cursor.Cursor; import org.apache.ibatis.session.RowBounds; /** * 用户Mapper * * @author VampireAchao */ @Mapper public interface UserMapper { /** * 流式分页查询用户 * * @param rowBounds 分页条件 * @return 用户流 */ Cursor<UserPO> selectPageCursor(RowBounds rowBounds); }
xml
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.ruben.mapper.UserMapper"> <select id="selectPageCursor" resultType="com.ruben.pojo.po.UserPO"> select * from User </select> </mapper>
po：
package com.ruben.pojo.po; import lombok.Data; import java.io.Serializable; /** * 用户PO * * @author VampireAchao */ @Data public class UserPO implements Serializable { private static final long serialVersionUID = -7219188882388819210L; private Long id; private String name; private Integer age; private String email; private Integer version; }
执行以下测试用例：
完整代码：
