running struts+tomcat6 application in linux+openJDK error

I get the following exception when trying to run my application in eclipse.

    Caused by: Unable to load configuration. - Class: java.net.AbstractPlainSocketImpl
    File: AbstractPlainSocketImpl.java
    Method: connect
    Line: 158 - java/net/AbstractPlainSocketImpl.java:158:-1
    at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:58)
    at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:374)
    at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:418)
    ... 20 more
    Caused by: Unable to load jar:file:/var/lib/tomcat6/webapps/webapps/cute/WEB-         INF/lib    /struts2-jfreechart-plugin-2.3.4.jar!/struts-plugin.xml - Class:    java.net.AbstractPlainSocketImpl
File: AbstractPlainSocketImpl.java
Method: connect
Line: 158 - java/net/AbstractPlainSocketImpl.java:158:-1
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:898)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadDocuments(XmlConfigurationProvider.java:143)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.init(XmlConfigurationProvider.java:110)
    at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:168)
    at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:55)
    ... 22 more
Caused by: struts.apache.org - Class: java.net.AbstractPlainSocketImpl
File: AbstractPlainSocketImpl.java
Method: connect
Line: 158 - java/net/AbstractPlainSocketImpl.java:158:-1
    at com.opensymphony.xwork2.util.DomHelper.parse(DomHelper.java:115)
    at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.loadConfigurationFiles(XmlConfigurationProvider.java:893)
    ... 26 more
Caused by: java.net.UnknownHostException: struts.apache.org
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:158)
    at java.net.Socket.connect(Socket.java:546)
    at java.net.Socket.connect(Socket.java:495)
    at sun.net.NetworkClient.doConnect(NetworkClient.java:174)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:409)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:530)
    at sun.net.www.http.HttpClient.<init>(HttpClient.java:240)
    at sun.net.www.http.HttpClient.New(HttpClient.java:321)
    at sun.net.www.http.HttpClient.New(HttpClient.java:338)
    at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:814)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:755)
    at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:680)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1005)
    at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(XMLEntityManager.java:653)
    at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startEntity(XMLEntityManager.java:1291)
    at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.startDTDEntity(XMLEntityManager.java:1258)
    at com.sun.org.apache.xerces.internal.impl.XMLDTDScannerImpl.setInputSource(XMLDTDScannerImpl.java:259)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.dispatch(XMLDocumentScannerImpl.java:1167)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$DTDDriver.next(XMLDocumentScannerImpl.java:1064)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:977)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:624)
    at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:116)
    at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:486)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:810)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:740)
    at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:110)
    at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1208)
    at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:525)
    at javax.xml.parsers.SAXParser.parse(SAXParser.java:392)
    at com.opensymphony.xwork2.util.DomHelper.parse(DomHelper.java:113)
    ... 27 more

I have configured the default server within Eclipse and added the jar files to the path.Placed the jar files in the lib folder.

Answers

If you receive an exception like

during the building of the Struts2 XML configuration, then something is preventing the application from successfully retrieving the DTD.

Changing the doctype declaration from

   <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN" "http://struts.apache.org/dtds/struts-2.3.dtd">

to either a local reference or just copying and pasting the DTD contents into its place will resolve the issue.

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