mybatis 别再用foreach批量插入了,ExecutorType点BATCH更加高效的批量插入,省带宽,省时,查错方便

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一、在mybatis中ExecutorType的使用

  1. Mybatis内置的ExecutorType有3种,默认的是simple,该模式下它为每个语句的执行创建一个新的预处理语句,单条提交sql;而batch模式重复使用已经预处理的语句, 并且批量执行所有更新语句,显然batch性能将更优;

  2. 但batch模式也有自己的问题,比如在Insert操作时,在事务没有提交之前,是没有办法获取到自增的id,这在某型情形下是不符合业务要求的;

  3. 在测试中使用simple模式提交10000条数据,时间为18248 毫秒,batch模式为5023 ,性能提高70%;

@Test
public void mybatisBatch() {
    SqlSession session = getSqlSessionFactory().openSession();
    try {
        DeptMapper deptMapper = (DeptMapper) session.getMapper(DeptMapper.class);
        long start =System.currentTimeMillis();
        for (int i = 0; i <10000 ; i++) {
            SysDept dept=new SysDept(UUID.randomUUID().toString().substring(1,6), 1, new Date(),  new Date(), 1);
            deptMapper.saveSysDept(dept);
        }
        long end =System.currentTimeMillis();
        System.out.println("耗时:"+(end-start));
        //ExecutorType.BATCH 批量耗时耗时:2134
        //单条操作耗时 耗时:8584
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        session.commit();
        session.close();
    }
}
@Test
public void saveDeptBatchOne() {
    SqlSession session = getSqlSessionFactory().openSession();
    try {
        DeptMapper deptMapper = (DeptMapper) session.getMapper(DeptMapper.class);
        long start =System.currentTimeMillis();
        List<SysDept> deptList=new ArrayList<SysDept>();
        for (int i = 0; i <100000 ; i++) {
            SysDept dept=new SysDept(UUID.randomUUID().toString().substring(1,6), 1, new Date(),  new Date(), 1);
            deptList.add(dept);
            if(i%500==0){
                deptMapper.saveDeptBatch(deptList);
                deptList.clear();
            }
        }
        deptMapper.saveDeptBatch(deptList);
        long end =System.currentTimeMillis();
        System.out.println("耗时:"+(end-start));
        //非BATCH批量耗时 耗时:938
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        session.commit();
        session.close();
    }
}
@Test
public void saveDeptBatchTwo() {
    //设置ExecutorType.BATCH原理:把SQL语句发个数据库,数据库预编译好,数据库等待需要运行的参数,接收到参数后一次运行,ExecutorType.BATCH只打印一次SQL语句,多次设置参数步骤,
    SqlSession session = getSqlSessionFactory().openSession(ExecutorType.BATCH);
    try {
        DeptMapper deptMapper = (DeptMapper) session.getMapper(DeptMapper.class);
        long start =System.currentTimeMillis();
        List<SysDept> deptList=new ArrayList<SysDept>();
        for (int i = 0; i <100000; i++) {
            SysDept dept=new SysDept(UUID.randomUUID().toString().substring(1,6), 1, new Date(),  new Date(), 1);
            deptList.add(dept);
            if(i%500==0){
                deptMapper.saveDeptBatch(deptList);
                deptList.clear();
            }
        }
        deptMapper.saveDeptBatch(deptList);
        long end =System.currentTimeMillis();
        System.out.println("耗时:"+(end-start));
        //BATCH批量耗时 耗时:822
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        session.commit();
        session.close();
    }
}

二、在mybatis+spring中ExecutorType的使用 1、在spring配置文件中添加批量执行的SqlSessionTemplate

<!--配置一个可以进行批量执行的sqlSession  -->
<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
    <constructor-arg name="sqlSessionFactory" ref="sqlSessionFactoryBean"></constructor-arg>
    <constructor-arg name="executorType" value="BATCH"></constructor-arg>
</bean>

2、service中获取批量添加的SqlSession

@Service
public class DeptService {
  @Autowired
  private DeptMapper deptMapper;

  @Autowired
  private SqlSession sqlSession;

  public List<Dept> addDept(){
      //executorType=BATCH 添加操作
      DeptMapper mapper = sqlSession.getMapper(DeptMapper.class);
      return mapper.saveDept(Dept);
  }
}

三、$和#的区别

#{}:可以获取map中的值或者pojo对象属性的值;

#{}:可以获取map中的值或者pojo对象属性的值;

${}:可以获取map中的值或者pojo对象属性的值;

select * from tbl_employee where id=${id} and last_name=#{lastName}
Preparing: select * from tbl_employee where id=2 and last_name=?
	 区别:
	 	#{}:是以预编译的形式,将参数设置到sql语句中;PreparedStatement;防止sql注入
	 	${}:取出的值直接拼装在sql语句中;会有安全问题;

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