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Posted on 2007-11-12 16:29 G_G 閱讀(2075) 評論(3) 編輯 收藏 所屬分類: hibernate
緩存問題：
????
/**
?使用?Query.executeUpdate()?緩存中數據不同步?解決辦法
?????*??Table?->?T1oo(id,name)
?????*?Table?->?T2oo(id,avg,aid)
?????*?外鍵?T1oo.id->T2oo.aid
?????*??Session.createQuery("delete?T1oo")?->??Query.executeUpdate()?
????
*/
????
public
?
void
?testExecuteUpdate(){
????????System.out.println(
"
\r\n\r\n********************ExecuteUpdate************************
"
);
????????T1oo?t1oo?
=
?
new
?T1oo();
????????t1oo.setName(
"
liukaiyi
"
);
????????
????????HibernateSessionFactory.closeSession();
????????
????????Session?session?
=
?HibernateSessionFactory.currentSession();
????Transaction?tr1?
=
?session.beginTransaction();
????????
//
t1?成為?持久狀態?一級緩存中?加載
????????session.saveOrUpdate(t1oo);?
????????
//
直接一條語句刪除T1oo，緩存無法同步
????????
//
一級緩存中還有?t1
????????Query?qu?
=
?session.createQuery(
"
delete?T1oo
"
);
????????
try
?{
????????????qu.executeUpdate();
????????}?
catch
?(Exception?e)?{????
????????????System.out.println(
"
//err:?有級聯?單使用?delete?T1oo?還要delete?T2oo.aid?=?T1oo.id//
"
);
????????????List?list?
=
?session.createQuery(
"
from?T1oo
"
).list();
????????????
for
(Iterator?it
=
list.iterator();it.hasNext();){
????????????????Query?t2qu?
=
?session.createQuery(
"
delete?T2oo??where?aid=:id
"
);
????????????????t2qu.setInteger(
"
id
"
,?((T1oo)it.next()).getId().intValue());
????????????????t2qu.executeUpdate();????????????????
????????????}
????????????qu.executeUpdate();
????????}
????????
????????tr1.commit();
????????
????Transaction?tr2?
=
?session.beginTransaction();
????????
//
這直接通過一級緩存中加載t2，但DB中以沒有此條數據
????????t1oo?
=
?(T1oo)session.load(T1oo.
class
,t1oo.getId());
????????t1oo.setName(
"
google
"
);
????????
try
?{
????????????tr2.commit();????
????????}?
catch
?(Exception?e)?{
????????????System.out.println(
"
//err:?update(t1oo)->DB?中數據庫中沒有?t1oo?//
"
);
????????}
????????
????????System.out.println(
"
?一級緩存清空前?
"
+
?session.get(T1oo.
class
,t1oo.getId())?);
????????session.evict(t1oo);
????????System.out.println(
"
?一級緩存清空后?
"
+
?session.get(T1oo.
class
,t1oo.getId())?);
????????
????????
//
不把t1oo?id?為空，否則當在saveOrUpdate時候就會以為是游離態?update了
????????t1oo.setId(
null
);
????????
//
id=null?insert?調用
????????session.saveOrUpdate(t1oo);????????
????????tr2.commit();
????????
????Transaction?tr3?
=
?session.beginTransaction();
????????session.delete(t1oo);
????????tr3.commit();
????????
????????session.close();
????????HibernateSessionFactory.closeSession();
????????
????}
結果是：
********************ExecuteUpdate************************
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Hibernate: insert into t1oo (name, id) values (?, ?)
Hibernate: delete from t1oo
//err: 有級聯 單使用 delete T1oo 還要delete T2oo.aid = T1oo.id//
Hibernate: select t1oo0_.id as id, t1oo0_.name as name0_ from t1oo t1oo0_
Hibernate: delete from t2oo where aid=?
Hibernate: delete from t2oo where aid=?
Hibernate: delete from t2oo where aid=?
Hibernate: delete from t1oo
Hibernate: update t1oo set name=? where id=?
//err: update(t1oo)->DB 中數據庫中沒有 t1oo //
?一級緩存清空前 hbn.bean.T1oo@287
Hibernate: select t1oo0_.id as id0_, t1oo0_.name as name0_0_ from t1oo t1oo0_ where t1oo0_.id=?
?一級緩存清空后 null
Hibernate: insert into t1oo (name, id) values (?, ?)
Hibernate: delete from t1oo where id=?
Get Load 區別 ：
?????/**?Get?Load?區別?(在commit前要?session.flush())
?????*?Table?->?T1oo(id,name)
?????*?1.如果未能發現符合條件的記錄，get方法返回null，而load方法會拋出異常
?????*?2.Load方法可返回實體的代理類實例，而get方法永遠直接返回實體類。
?????*?3.load方法可以充分利用內部緩存和二級緩存中的現有數據，而get方法則僅僅在內部緩存中進行數據查找，
?????*?????????????如沒有發現對應數據，將越過二級緩存，直接調用SQL完成數據讀取。?
?????*/
????public?void?testGetLoad()?throws?Exception?{
????????System.out.println("\r\n\r\n********************Get<>Load************************");
????????Session?session?=?HibernateSessionFactory.currentSession();
????//??數據準備
????????T1oo?t1oo?=?new?T1oo();
????????t1oo.setName("liu");
????Transaction?t1?=?session.beginTransaction();
????????session.saveOrUpdate(t1oo);
????????//?為什么這會錯？
????????//session.evict(t1oo);
????????//session.flush();
????????t1.commit();
????????session.evict(t1oo);
????
????Transaction?t2?=?session.beginTransaction();
????????System.out.println("一級緩存是否有t1oo(load)->"+session.contains(t1oo));?
????????//這時候t1oo為?CGlib生成的代理類
????????t1oo?=?(T1oo)session.load(T1oo.class,t1oo.getId());
????????System.out.println("?延遲加載出現：select..?t1oo0_.id=??表的其他屬性加載?");
????????t1oo.setName("load?list");
????????//后在?update
????????t2.commit();
????????session.evict(t1oo);
????????
????Transaction?t3?=?session.beginTransaction();
????????System.out.println("一級緩存是否有t1oo(get)->"+session.contains(t1oo));?
????????//這時候t1oo為?CGlib生成的代理類
????????t1oo?=?(T1oo)session.get(T1oo.class,t1oo.getId());
????????System.out.println("?沒有延遲加載出現");
????????t1oo.setName("get?list");
????????//后在?update
????????t3.commit();????
????????session.evict(t1oo);
????????
????Transaction?tr3?=?session.beginTransaction();
????????session.delete(t1oo);
????????tr3.commit();
????????
????????session.close();
????????HibernateSessionFactory.closeSession();
????????
????}
結果
********************Get<>Load************************
Hibernate: insert into t1oo (name, id) values (?, ?)
一級緩存是否有t1oo(load)->false
?延遲加載出現：select.. t1oo0_.id=? 表的其他屬性加載
Hibernate: select t1oo0_.id as id0_, t1oo0_.name as name0_0_ from t1oo t1oo0_ where t1oo0_.id=?
Hibernate: update t1oo set name=? where id=?
一級緩存是否有t1oo(get)->false
Hibernate: select t1oo0_.id as id0_, t1oo0_.name as name0_0_ from t1oo t1oo0_ where t1oo0_.id=?
?沒有延遲加載出現
Hibernate: update t1oo set name=? where id=?
Hibernate: select t2ooset0_.aid as aid1_, t2ooset0_.id as id1_, t2ooset0_.id as id0_, t2ooset0_.avg as avg1_0_, t2ooset0_.aid as aid1_0_ from t2oo t2ooset0_ where t2ooset0_.aid=?
Hibernate: delete from t1oo where id=?
Set 集合的識別：
????/**?Set?集合的識別
?????*?Table?->?T1oo(id,name)
?????*?Table?->?T2oo(id,avg,aid)
?????*?外鍵?T1oo.id->T2oo.aid
?????*?T1oo??<set?name="t2ooSet"?inverse="false"?cascade?=?"all"??>
?????*?T2oo??<many-to-one?name="t1oo"?column="aid"?class="T1oo"?/>
?????*?cascade='insert'?是一定要的
?????*?????當?T1oo沒有?inverse="true"?主動權的時候，要雙項關聯
?????*?????t1oo.getT2ooSet().add(t2oo1);
?????*????t1oo.getT2ooSet().add(t2oo2);
?????*????t2oo1.setT1oo(t1oo);
?????*????t2oo2.setT1oo(t1oo);
?????*??要不后sql為：
?????*??Hibernate:?insert?into?t2oo?(avg,?aid,?id)?values?(?,??,??)
?????*????Hibernate:?insert?into?t2oo?(avg,?aid,?id)?values?(?,??,??)
?????*????+----+-----+------+
?????*????|?id?|?avg?|?aid??|
?????*????+----+-----+------+
?????*????|??1?|??24?|?NULL?|
?????*????|??2?|??23?|?NULL?|
?????*????+----+-----+------+
?????*????當?T1oo有?inverse="false"主動權的時候
?????*??t1oo.getT2ooSet().add(t2oo1);
?????*????t1oo.getT2ooSet().add(t2oo2);
?????*??Sql語句為：
?????*??Hibernate:?insert?into?t1oo?(name,?id)?values?(?,??)
?????*????Hibernate:?insert?into?t2oo?(avg,?aid,?id)?values?(?,??,??)
?????*????Hibernate:?insert?into?t2oo?(avg,?aid,?id)?values?(?,??,??)
?????*????Hibernate:?update?t2oo?set?aid=??where?id=?
?????*????Hibernate:?update?t2oo?set?aid=??where?id=?
?????*????|??3?|??24?|???12?|
?????*????|??4?|??23?|???12?|
?????*????+----+-----+------+
????*/
????public?void?testSet(){
????????System.out.println("\r\n\r\n********************Set************************");
????????T1oo?t1oo?=?new?T1oo();
????????t1oo.setName("list");
????????
????????T2oo?t2oo1?=?new?T2oo();?t2oo1.setAvg(new?Integer(23));
????????T2oo?t2oo2?=?new?T2oo();?t2oo2.setAvg(new?Integer(24));
????????
????????
????????Session?session?=?HibernateSessionFactory.currentSession();
????????Transaction?tr1?=?session.beginTransaction();
????????session.save(t1oo);
????????t1oo?=?(T1oo)?session.load(T1oo.class,t1oo.getId());
????????t1oo.setT2ooSet(new?HashSet())?;
????????t1oo.getT2ooSet().add(t2oo1);
????????t1oo.getT2ooSet().add(t2oo2);
?????????
????????System.out.println(?t1oo.getT2ooSet().size()+""?);????????
????????tr1.commit();
????????
????????System.out.println();
????????T2oo?t2oo3?=?new?T2oo();?t2oo3.setAvg(new?Integer(25));
????????T1oo?t1oo2?=?new?T1oo();?t1oo2.setName("mz");
????????t2oo3.setT1oo(t1oo2);
????????
????????Transaction?tr2?=?session.beginTransaction();
????????session.save(t2oo3);
????????try?{
????????????tr2.commit();????
????????}?catch?(Exception?e)?{
????????????System.out.println("//err:?沒有主動權?cascade?=?'all'?不可以級聯save?t1oo???//");
????????}
????????session.close();
????????HibernateSessionFactory.closeSession();
????}
???
結果是：
********************Set************************
2
Hibernate: insert into t1oo (name, id) values (?, ?)
Hibernate: insert into t2oo (avg, aid, id) values (?, ?, ?)
Hibernate: insert into t2oo (avg, aid, id) values (?, ?, ?)
Hibernate: update t2oo set aid=? where id=?
Hibernate: update t2oo set aid=? where id=?
//err: 沒有主動權 cascade = 'all' 不可以級聯save t1oo?? //
評論
# re: hibernate 部分問題總結——1 回復 更多評論
2007-11-19 20:04 by
不錯，收藏
# re: hibernate 部分問題總結——1[未登錄] 回復 更多評論
2009-02-14 11:23 by
session.close();
HibernateSessionFactory.closeSession();
為什么要調用兩次
# re: hibernate 部分問題總結——1 回復 更多評論
2009-02-16 09:27 by
第一次 session.close(); 為本線程的session關閉
HibernateSessionFactory.closeSession(); 第二次為 全部連接斷開
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