hibernate 批量操作

 

java 批量操作

网数据表里插入100 0000 条记录

 

EntityTransaction tx = em.getTransaction();tx.begin();int i=0;try {for(;i<1000000;i++){User user = new User();user.setAge(18);user.setUsername("sddfdf");user.setPassword("taoge");Account account = new Account();account.setMoney(11111);account.setUser(user);em.persist(account);System.out.println(i);}} catch (Exception e) {System.out.println(i);e.printStackTrace();}tx.commit();

 

当运行到 

.............

470805
470806 

的时候会抛出 java.lang.OutOfMemoryError 异常：

 

Exception in thread "main" java.lang.OutOfMemoryError: Java heap spaceat java.util.Arrays.copyOf(Arrays.java:2882)at java.lang.AbstractStringBuilder.expandCapacity(AbstractStringBuilder.java:100)at java.lang.AbstractStringBuilder.append(AbstractStringBuilder.java:390)at java.lang.StringBuilder.append(StringBuilder.java:119)at java.lang.StringBuilder.append(StringBuilder.java:115)at org.hibernate.id.IdentifierGeneratorHelper.getGeneratedIdentity(IdentifierGeneratorHelper.java:87)at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:98)at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:57)at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2327)at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2834)at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:71)at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:273)at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:320)at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:203)at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:129)at org.hibernate.ejb.event.EJB3PersistEventListener.saveWithGeneratedId(EJB3PersistEventListener.java:69)at org.hibernate.event.def.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:179)at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:135)at org.hibernate.impl.SessionImpl.firePersist(SessionImpl.java:799)at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:791)at org.hibernate.engine.EJB3CascadingAction$1.cascade(EJB3CascadingAction.java:48)at org.hibernate.engine.Cascade.cascadeToOne(Cascade.java:392)at org.hibernate.engine.Cascade.cascadeAssociation(Cascade.java:335)at org.hibernate.engine.Cascade.cascadeProperty(Cascade.java:204)at org.hibernate.engine.Cascade.cascade(Cascade.java:161)at org.hibernate.event.def.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:450)at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:282)at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:203)at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:129)at org.hibernate.ejb.event.EJB3PersistEventListener.saveWithGeneratedId(EJB3PersistEventListener.java:69)at org.hibernate.event.def.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:179)at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:135)

 

 

此时 select  数据表 ， 数据一条没插入进去，原因很明显， 程序在 tx.commit(); 之前挂掉了

 

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优化：

 

for(;i<1000000;i++){User user = new User();user.setAge(18);user.setUsername("wangtao");user.setPassword("taoge");Account account = new Account();account.setMoney(11111);account.setUser(user);em.persist(account);if(i % 100 == 0){em.flush();// 将一级缓存中的数据送往二级缓存em.clear();// 清空一级缓存}System.out.println(i);}

 

当程序执循环完1000000次， tx.commit();  ok  大功告成！！！