错误的详细信息：
严重: Dispatcher initialization failed
Unable to load configuration. - Class: com.sun.org.apache.xml.internal.serializer.OutputPropertiesFactory
File: OutputPropertiesFactory.java
Method: getDefaultMethodProperties
Line: 320 - com/sun/org/apache/xml/internal/serializer/OutputPropertiesFactory.java:320:-1
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:69)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:390)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:436)
at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:74)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:51)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:295)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4072)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4726)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:675)
at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:601)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:502)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
at org.apache.catalina.core.StandardService.start(StandardService.java:525)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
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:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: Caught exception while loading file struts-default.xml - Class: com.sun.org.apache.xml.internal.serializer.OutputPropertiesFactory
File: OutputPropertiesFactory.java
Method: getDefaultMethodProperties
Line: 320 - com/sun/org/apache/xml/internal/serializer/OutputPropertiesFactory.java:320:-1
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:950)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadDocuments(XmlConfigurationProvider.java:155)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.init(XmlConfigurationProvider.java:122)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:205)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66)
... 31 more
Caused by: com.sun.org.apache.xml.internal.serializer.utils.WrappedRuntimeException: 无法为输出方法“xml”装载属性文件“output_xml.properties”（检查 CLASSPATH）
at com.sun.org.apache.xml.internal.serializer.OutputPropertiesFactory.getDefaultMethodProperties(OutputPropertiesFactory.java:320)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.setDefaults(TransformerImpl.java:1119)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.createOutputProperties(TransformerImpl.java:1080)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.<init>(TransformerImpl.java:246)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.<init>(TransformerImpl.java:237)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl.newTransformer(TransformerFactoryImpl.java:592)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl.newTransformerHandler(TransformerFactoryImpl.java:883)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.setup(DomHelper.java:198)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.<init>(DomHelper.java:190)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.<init>(DomHelper.java:181)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.<init>(DomHelper.java:167)
at com.opensymphony.xwork2.util.DomHelper.parse(DomHelper.java:107)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:941)
... 35 more
2012-5-18 16:18:32 org.apache.catalina.core.StandardContext filterStart
严重: Exception starting filter struts2
Unable to load configuration. - Class: com.sun.org.apache.xml.internal.serializer.OutputPropertiesFactory
File: OutputPropertiesFactory.java
Method: getDefaultMethodProperties
Line: 320 - com/sun/org/apache/xml/internal/serializer/OutputPropertiesFactory.java:320:-1
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:449)
at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:74)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.init(StrutsPrepareAndExecuteFilter.java:51)
at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:295)
at org.apache.catalina.core.ApplicationFilterConfig.setFilterDef(ApplicationFilterConfig.java:422)
at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:115)
at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4072)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4726)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:601)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:675)
at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:601)
at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:502)
at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:840)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
at org.apache.catalina.core.StandardService.start(StandardService.java:525)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
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:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)
Caused by: Unable to load configuration. - Class: com.sun.org.apache.xml.internal.serializer.OutputPropertiesFactory
File: OutputPropertiesFactory.java
Method: getDefaultMethodProperties
Line: 320 - com/sun/org/apache/xml/internal/serializer/OutputPropertiesFactory.java:320:-1
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:69)
at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:390)
at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:436)
... 29 more
Caused by: Caught exception while loading file struts-default.xml - Class: com.sun.org.apache.xml.internal.serializer.OutputPropertiesFactory
File: OutputPropertiesFactory.java
Method: getDefaultMethodProperties
Line: 320 - com/sun/org/apache/xml/internal/serializer/OutputPropertiesFactory.java:320:-1
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:950)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadDocuments(XmlConfigurationProvider.java:155)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.init(XmlConfigurationProvider.java:122)
at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:205)
at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:66)
... 31 more
Caused by: com.sun.org.apache.xml.internal.serializer.utils.WrappedRuntimeException: 无法为输出方法“xml”装载属性文件“output_xml.properties”（检查 CLASSPATH）
at com.sun.org.apache.xml.internal.serializer.OutputPropertiesFactory.getDefaultMethodProperties(OutputPropertiesFactory.java:320)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.setDefaults(TransformerImpl.java:1119)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.createOutputProperties(TransformerImpl.java:1080)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.<init>(TransformerImpl.java:246)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl.<init>(TransformerImpl.java:237)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl.newTransformer(TransformerFactoryImpl.java:592)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl.newTransformerHandler(TransformerFactoryImpl.java:883)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.setup(DomHelper.java:198)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.<init>(DomHelper.java:190)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.<init>(DomHelper.java:181)
at com.opensymphony.xwork2.util.DomHelper$DOMBuilder.<init>(DomHelper.java:167)
at com.opensymphony.xwork2.util.DomHelper.parse(DomHelper.java:107)
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:941)
... 35 more
2012-5-18 16:18:32 org.apache.catalina.core.StandardContext start
严重: Error filterStart
2012-5-18 16:18:32 org.apache.catalina.core.StandardContext start
严重: Context [/javaee_struts2] startup failed due to previous errors
2012-5-18 16:18:32 org.apache.catalina.startup.HostConfig deployDescriptor
1. struts2.3 框架搭建的项目，所用环境为：eclipse + tamcat 6
2. 解决方法：
到这个网站 http://labs.renren.com/apache-mirror/xml/xalan-j/ 下载 xalan-j_2_7_1-bin.zip
然后将这个压缩包中的四个jar包（或serializer.jar与xalan.jar）放到tomcat的lib目录下。
更新服务器，重新启动问题解决。