无意间struts应用在有网络的情况下启动正常，在断网的情况下启动报错，报错代码如下图所示：
SEVERE: Exception starting filter struts2 Class: java.net.AbstractPlainSocketImpl File: AbstractPlainSocketImpl.java Method: connect Line: 178 - java/net/AbstractPlainSocketImpl.java:178:-1 at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:835) at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadDocuments(XmlConfigurationProvider.java:131) at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.init(XmlConfigurationProvider.java:100) at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reload(DefaultConfiguration.java:130) at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:52) at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:395) at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:452) at org.apache.struts2.dispatcher.FilterDispatcher.init(FilterDispatcher.java:201) at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:281) at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:262) at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:107) at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4746) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5399) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901) at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877) at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:633) at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:657) at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1636) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) at java.util.concurrent.FutureTask.run(FutureTask.java:166) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:722) Caused by: struts.apache.org - Class: java.net.AbstractPlainSocketImpl File: AbstractPlainSocketImpl.java Method: connect Line: 178 - java/net/AbstractPlainSocketImpl.java:178:-1 at com.opensymphony.xwork2.util.DomHelper.parse(DomHelper.java:123) at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:830) ... 24 more Caused by: java.net.UnknownHostException: struts.apache.org at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:178) at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:157) at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:391) at java.net.Socket.connect(Socket.java:579) at java.net.Socket.connect(Socket.java:528) at sun.net.NetworkClient.doConnect(NetworkClient.java:180) at sun.net.www.http.HttpClient.openServer(HttpClient.java:378) at sun.net.www.http.HttpClient.openServer(HttpClient.java:473) at sun.net.www.http.HttpClient.<init>(HttpClient.java:203) at sun.net.www.http.HttpClient.New(HttpClient.java:290) at sun.net.www.http.HttpClient.New(HttpClient.java:306) at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:995) at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:931) at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:849) at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1299) at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(XMLEntityManager.java:632) at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startEntity(XMLEntityManager.java:1270) at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startDTDEntity(XMLEntityManager.java:1237) at com.sun.org.apache.xerces.internal.impl.XMLDTDScannerImpl.setInputSource(XMLDTDScannerImpl.java:260) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.dispatch(XMLDocumentScannerImpl.java:1153) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.next(XMLDocumentScannerImpl.java:1049) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:962) at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:607) at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:116) at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:489) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:835) at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:764) at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:123) at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1210) at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:568) at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl.parse(SAXParserImpl.java:302) at com.opensymphony.xwork2.util.DomHelper.parse(DomHelper.java:121) ... 25 more 三月 20, 2014 9:25:36 上午 org.apache.catalina.core.StandardContext startInternal
查看struts.xml文件的DOCTYPE定义如下：
1 <!DOCTYPE struts PUBLIC 2 "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" 3 "http://struts.apache.org/dtds/struts-2.1.dtd">
再查看xwork的jar包是2.0的，所以将DOCTYPE的定义也改成2.0的即可
1 <!DOCTYPE struts PUBLIC 2 "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" 3 "http://struts.apache.org/dtds/struts-2.0.dtd">