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避免重复加载

分类: IT文章 • 2024-12-23 11:34:01
场景：【高分】【紧急】【】hibernate怎么避免重复加载配置文件，多谢

【高分】【紧急】【在线等】hibernate如何避免重复加载配置文件，谢谢~
Java code
 2008 十月 28 23:45:00,317 [INFO] org.hibernate.cfg.Environment - Hibernate 3.3.1.GA 
  2008 十月 28 23:45:00,332 [INFO] org.hibernate.cfg.Environment - hibernate.properties not found 
  2008 十月 28 23:45:00,332 [INFO] org.hibernate.cfg.Environment - Bytecode provider name : javassist 
  2008 十月 28 23:45:00,348 [INFO] org.hibernate.cfg.Environment - using JDK 1.4 java.sql.Timestamp handling 
  2008 十月 28 23:45:00,551 [INFO] org.hibernate.cfg.Configuration - configuring from resource: /hibernate.cfg.xml 
  2008 十月 28 23:45:00,551 [INFO] org.hibernate.cfg.Configuration - Configuration resource: /hibernate.cfg.xml 
  2008 十月 28 23:45:00,770 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/AdminPower.hbm.xml 
  2008 十月 28 23:45:00,973 [INFO] org.hibernate.cfg.HbmBinder - Mapping class: cn.hlgc.hibernate.AdminPower -> admin_power 
  2008 十月 28 23:45:01,082 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/Airport.hbm.xml 
  2008 十月 28 23:45:01,129 [INFO] org.hibernate.cfg.HbmBinder - Mapping class: cn.hlgc.hibernate.Airport -> airports 
  2008 十月 28 23:45:01,129 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/Album.hbm.xml 
  2008 十月 28 23:45:01,160 [INFO] org.hibernate.cfg.HbmBinder - Mapping class: cn.hlgc.hibernate.Album -> albums 
  2008 十月 28 23:45:01,176 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/AlbumPhoto.hbm.xml 
  2008 十月 28 23:45:01,239 [INFO] org.hibernate.cfg.HbmBinder - Mapping class: cn.hlgc.hibernate.AlbumPhoto -> album_photos 
  2008 十月 28 23:45:01,285 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/AlbumUser.hbm.xml 
  2008 十月 28 23:45:01,317 [INFO] org.hibernate.cfg.HbmBinder - Mapping class: cn.hlgc.hibernate.AlbumUser -> album_users 
  2008 十月 28 23:45:01,317 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/Aod.hbm.xml 
  2008 十月 28 23:45:01,348 [INFO] org.hibernate.cfg.HbmBinder - Mapping class: cn.hlgc.hibernate.Aod -> aod 
  2008 十月 28 23:45:01,379 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/AodSort.hbm.xml 
  2008 十月 28 23:45:01,551 [INFO] org.hibernate.cfg.HbmBinder - Mapping class: cn.hlgc.hibernate.AodSort -> aod_sorts 
  2008 十月 28 23:45:01,582 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/Attachment.hbm.xml 
  2008 十月 28 23:45:01,614 [INFO] org.hibernate.cfg.HbmBinder - Mapping class: cn.hlgc.hibernate.Attachment -> attachments 
  2008 十月 28 23:45:01,629 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/Blog.hbm.xml 
 [color=#FF0000]============================.hbm.xml的列表还没加载完毕，hibernate.cfg.xml又重新开始加载了[/color] 
  2008 十月 28 23:45:01,832 [INFO] org.hibernate.cfg.Configuration - configuring from resource: /hibernate.cfg.xml 
  2008 十月 28 23:45:01,832 [INFO] org.hibernate.cfg.Configuration - Configuration resource: /hibernate.cfg.xml 
  2008 十月 28 23:45:01,864 [INFO] org.hibernate.cfg.Configuration - configuring from resource: /hibernate.cfg.xml 
  2008 十月 28 23:45:01,864 [INFO] org.hibernate.cfg.Configuration - Configuration resource: /hibernate.cfg.xml 
  2008 十月 28 23:45:01,895 [ERROR] org.apache.catalina.core.ContainerBase.[Catalina].[www.javafeng.cn].[/] - Session event listener threw exception 
  java.lang.NullPointerException 
 	at cn.hlgc.util.HibernateUtil.beginTransaction(HibernateUtil.java:106) 
 	at cn.hlgc.stat.OnlineListener.sessionDestroyed(OnlineListener.java:70) 
 	at org.apache.catalina.session.StandardSession.expire(StandardSession.java:687) 
 	at org.apache.catalina.session.StandardSession.isValid(StandardSession.java:579) 
 	at org.apache.catalina.session.ManagerBase.processExpires(ManagerBase.java:678) 
 	at org.apache.catalina.session.ManagerBase.backgroundProcess(ManagerBase.java:663) 
 	at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1284) 
 	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1569) 
 	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1578) 
 	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1578) 
 	at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1558) 
 	at java.lang.Thread.run(Thread.java:619) 
 [color=#FF0000]2008 十月 28 23:50:00,020 [INFO] org.hibernate.cfg.Configuration - configuring from resource: /hibernate.cfg.xml 
  2008 十月 28 23:50:00,020 [INFO] org.hibernate.cfg.Configuration - Configuration resource: /hibernate.cfg.xml 
  2008 十月 28 23:50:00,035 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/AdminPower.hbm.xml 
  2008 十月 28 23:50:00,082 [INFO] org.hibernate.cfg.Mappings - duplicate import: cn.hlgc.hibernate.AdminPower->cn.hlgc.hibernate.AdminPower 
  2008 十月 28 23:50:00,082 [INFO] org.hibernate.cfg.Mappings - duplicate import: cn.hlgc.hibernate.AdminPower->AdminPower[/color] 
  2008 十月 28 23:50:00,082 [INFO] org.hibernate.cfg.HbmBinder - Mapping class: cn.hlgc.hibernate.AdminPower -> admin_power 
  2008 十月 28 23:50:00,098 [INFO] org.hibernate.cfg.Configuration - configuring from resource: /hibernate.cfg.xml 
  2008 十月 28 23:50:00,098 [INFO] org.hibernate.cfg.Configuration - Configuration resource: /hibernate.cfg.xml 
  2008 十月 28 23:50:00,098 [INFO] org.hibernate.cfg.Configuration - Reading mappings from resource : cn/hlgc/hibernate/AdminPower.hbm.xml 
  2008 十月 28 23:50:00,145 [INFO] org.hibernate.cfg.Mappings - duplicate import: cn.hlgc.hibernate.AdminPower->cn.hlgc.hibernate.AdminPower 
  2008 十月 28 23:50:00,145 [INFO] org.hibernate.cfg.Mappings - duplicate import: cn.hlgc.hibernate.AdminPower->AdminPower 
  2008 十月 28 23:50:00,145 [INFO] org.hibernate.cfg.HbmBinder - Mapping class: cn.hlgc.hibernate.AdminPower -> admin_power 
  2008 十月 28 23:50:00,145 [ERROR] org.quartz.core.JobRunShell - Job stat.updateStat threw an unhandled Exception:  
  java.lang.NullPointerException 
 	at cn.hlgc.util.HibernateUtil.beginTransaction(HibernateUtil.java:106) 
 	at cn.hlgc.stat.UpdateStat.execute(UpdateStat.java:216) 
 	at org.quartz.core.JobRunShell.run(JobRunShell.java:202) 
 	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:529) 
 2008 十月 28 23:50:00,145 [ERROR] org.quartz.core.ErrorLogger - Job (stat.updateStat threw an exception. 
  org.quartz.SchedulerException: Job threw an unhandled exception. [See nested exception: java.lang.NullPointerException] 
 	at org.quartz.core.JobRunShell.run(JobRunShell.java:213) 
 	at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:529) 
 Caused by: java.lang.NullPointerException 
 	at cn.hlgc.util.HibernateUtil.beginTransaction(HibernateUtil.java:106) 
 	at cn.hlgc.stat.UpdateStat.execute(UpdateStat.java:216) 
 	at org.quartz.core.JobRunShell.run(JobRunShell.java:202) 
 	... 1 more


大家好，请看上面抛出的错误，在tomcat启动的时候，如果有取数据的访问，hibernate就会开始读取配置文件，连接数据库，但是如果在hibernate连接数据库的时候（比如正在读取配置文件，还没完成连接的时候），如果又有一个取数据的请求的话，hibernate就会在再次读取配置文件和连接数据库，这样就duplicate import了，请问如何才能解决这个问题，就是在hibernate还没完成连接的时候不再读取和连接数据库，应该如何设置，谢谢~感激~

------解决方案--------------------
将加载配置文件的语句放在static代码块中：
static{
configuration.configure(configFile);
sessionFactory = configuration.buildSessionFactory();
}
------解决方案--------------------
把 buildSessionFactory 过程的方法加上同步关键字，这点很重要，也不影响性能，因为这具操作只需要执行一次。
------解决方案--------------------
探讨
引用:
将加载配置文件的语句放在static代码块中：
static{
configuration.configure(configFile);
sessionFactory = configuration.buildSessionFactory();
}



Java code /**
* Rebuild hibernate session factory
*/
public static void rebuildSessionFactory() {
try {
configuration.configure(configFile);
sess…

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