我根据此网站配置了二级缓存 http://www.cnblogs.com/iloveu/archive/2009/02/16/1391392.html
现在报出
[code="java"]1.%%%% Error Creating SessionFactory %%%%
2.org.hibernate.MappingException: invalid configuration
3. at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2241)
4. at org.hibernate.cfg.AnnotationConfiguration.doConfigure(AnnotationConfiguration.java:230)
5. at org.hibernate.cfg.AnnotationConfiguration.doConfigure(AnnotationConfiguration.java:71)
6. at org.hibernate.cfg.Configuration.configure(Configuration.java:2158)
7. at org.hibernate.cfg.AnnotationConfiguration.configure(AnnotationConfiguration.java:212)
8. at org.hibernate.cfg.AnnotationConfiguration.configure(AnnotationConfiguration.java:71)
9. at com.huawei.ifree.autotest.log.analyse.platform.db.HibernateSessionFactory.updateHibernateCfg(HibernateSessionFactory.java:62)
10. at com.huawei.ifree.autotest.log.analyse.platform.db.HibernateSessionFactory.(HibernateSessionFactory.java:44)
11. at com.huawei.ifree.autotest.log.analyse.platform.servlet.ActivatorServlet.init(ActivatorServlet.java:53)
12. at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1173)
13. at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:993)
14. at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4187)
15. at org.apache.catalina.core.StandardContext.start(StandardContext.java:4496)
16. at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
17. at org.apache.catalina.core.StandardHost.start(StandardHost.java:785)
18. at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1045)
19. at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
20. at org.apache.catalina.core.StandardService.start(StandardService.java:519)
21. at org.apache.catalina.core.StandardServer.start(StandardServer.java:710)
22. at org.apache.catalina.startup.Catalina.start(Catalina.java:581)
23. at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
24. at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
25. at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
26. at java.lang.reflect.Method.invoke(Unknown Source)
27. at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
28. at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
29.Caused by: org.xml.sax.SAXParseException: The content of element type "session-factory" must match "(property*,mapping*,(class-cache|collection-cache)*,event*,listener*)".
30. at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:232)
31. at org.apache.xerces.util.ErrorHandlerWrapper.error(ErrorHandlerWrapper.java:173)
32. at org.apache.xerces.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:371)
33. at org.apache.xerces.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:305)
34. at org.apache.xerces.impl.dtd.XMLDTDValidator.handleEndElement(XMLDTDValidator.java:1918)
35. at org.apache.xerces.impl.dtd.XMLDTDValidator.endElement(XMLDTDValidator.java:851)
36. at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1008)
37. at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(XMLDocumentFragmentScannerImpl.java:1469)
38. at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:329)
39. at org.apache.xerces.parsers.DTDConfiguration.parse(DTDConfiguration.java:525)
40. at org.apache.xerces.parsers.DTDConfiguration.parse(DTDConfiguration.java:581)
41. at org.apache.xerces.parsers.XMLParser.parse(XMLParser.java:152)
42. at org.apache.xerces.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1175)
43. at org.dom4j.io.SAXReader.read(SAXReader.java:465)
44. at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2238)
45. ... 25 more
[/code]
[quote]查询缓存是直接缓存已经执行的那一条sql语句吗? 如果下次碰到语句一样的, 就到缓存里面去找吗?[/quote]
对啊，查询条件都要一样。
你的配置文件写错了呀
The content of element type "session-factory" must match "(property*,mapping*,(class-cache|collection-cache)*,event*,listener*)".
估计是property，mapping, class-cache|collection-cache， event， listener其中一个或者几个没有写对吧
在配置文件中配置开启二级缓冲
二级缓存都需要实现org.hibernate.cache.CacheProvider接口，Hibernate已经实现了一些缓存，开发人员可以直接配置使用，同时要启用二级缓存，配置hibernate.cache.use_second_level_cache为true。
可选值：
org.hibernate.cache.HashtableCacheProvide
org.hibernate.cache.EhCacheProvider
org.hibernate.cache.OSCacheProvider
org.hibernate.cache.SwarmCacheProvider
org.hibernate.cache.TreeCacheProvider...
org.hibernate.cache.EhCacheProvider
true
看这里
[url]http://log-cd.iteye.com/blog/355097[/url]
如果要从缓存里取得话应该根据对象的ID来查
楼主第一次查出来的东西已经放到缓存里了，第二次查的时候应该想办法根据ID查。
这样就不会访问数据库了
你说的是一级缓存吧, 二级缓存不是所有session共享吗? 如果也是只能根据id查询才行, 那配置这个就用处不大了
不是这样的。你想啊 如果是个查询语句，比如将年龄大于20的人查出来这样的查询，怎么可能去缓存里面查呢! 数据时刻都在变，你在缓存里面查出来的结果很可能是不正确的。要想从缓存里面取东西只有根据ID查出来的才有意义。
一般放到缓存里面的东西都是很少变化的东西。
至于缓存有啥好处等你到项目里面用了就知道了
[quote]
the second level cache will [b]only cache relations and entities you find on id[/b]. Queries can't be cached by the second level cache and will always go to the database (or query cache).
[/quote]
[quote]
2nd level cache contains only entities by their ids, so when retrieving an entity by id (i.e. get, load or resolving a proxy implicitly) a 2nd level cache may be accessed. Any other queries (hal, criteria) will bypass the cache and hit the DB - at least as long as no query cache is used as well.
[/quote]
二级缓存只对根据实体的ID来缓存实体，所以只有在通过ID获取实体时才有可能访问二级缓存，比如，get，load方法。所有其他查询都会跳过缓存直接命中数据库，至少在没有使用查询缓存时是这样的。
你可以试试 我觉得查询语句不太可能去缓存里面找呀。这样效率高但是结果不对呀
查询语句缓存的话 oracla也是缓存的。没有必要用它的。
oracle