xml解析出现问题

Question

org.xml.sax.SAXParseException: Premature end of file.
at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(DOMParser.java:264)
at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:292)
at javax.xml.parsers.DocumentBuilder.parse(DocumentBuilder.java:172)
at com.chinadim.timesheet.xml.PunishSetXmlParse.<init>(PunishSetXmlParse.java:50)
at com.chinadim.timesheet.xml.PunishSetXmlParse.getNewInstance(PunishSetXmlParse.java:66)
at com.chinadim.timesheet.action.PunishSet.list(PunishSet.java:27)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.opensymphony.xwork.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:300)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:166)
at com.opensymphony.xwork.interceptor.DefaultWorkflowInterceptor.intercept(DefaultWorkflowInterceptor.java:55)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:164)
at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:116)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.serviceAction(ServletDispatcher.java:272)
at com.opensymphony.webwork.dispatcher.ServletDispatcher.service(ServletDispatcher.java:237)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.chinadim.timesheet.filter.EntryFilter.doFilter(EntryFilter.java:68)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)
解析时碰到这个问题，在JSP页面中，刚开始显示xml中的数据，没问题。然后进行修改，提交之后，页面显示数据已经修改，但是xml文件中数据没有变化。再次进行修改提交后，就出现以上问题，请高手指点。

Answer 1

一个很奇快的现象：一个XML文件进行操作的时候，突然出现 
[Fatal Error] IP.xml:1:1: Premature end of file. 
org.xml.sax.SAXParseException: Premature end of file. 
的错误，找到对应的XML文件一看，文件大小为0个字节，这样再对解析后的文件进行操作，很明显就会跑出一个nullPointException的异常，但是出现这种情况的原因总是无法正确查到，你在对XML文件进行增、删、查、该的过程中它没有出问题，而后在一个莫名奇妙的时候就出现问题了，当你意识到这个问题再来对其进行捕获的时候，它又再次隐藏起来了，搞的人莫名奇妙！

Answer 2

这里有一例:
http://www.javamilk.cn/article/notes/936.htm

Answer 3

页面显示数据已经修改，但是xml文件中数据没有变化
为什么没有变化,知道原因吗?