我被 servlet 中的 DOM 解析器困住了。这是代码：
import java.awt.List;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import javax.lang.model.element.Element;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.swing.text.Document;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.DocumentBuilder;
import org.w3c.dom.NodeList;
import org.w3c.dom.Node;
import java.io.File;
import java.util.ArrayList;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
//import com.sun.xml.internal.bind.v2.schemagen.xmlschema.List;
public class RoutingParser extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter writer = response.getWriter();
System.out.println("Routing Parser is accessible");
System.out.println("i reached servlet");
try {
ArrayList inputlist1= new ArrayList();
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("D");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("N");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("US")
inputlist1.add("%");
inputlist1.add("%");
inputlist1.add("%");
ArrayList list1=new ArrayList();
System.out.println("i reached servlet");
try {
File fXmlFile = new File("c:\\eclipse\\RoutingTable.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
org.w3c.dom.Document doc = dBuilder.parse(fXmlFile);
doc.getDocumentElement().normalize();
System.out.println("Root element :" + doc.getDocumentElement().getNodeName());
NodeList nList = doc.getElementsByTagName("Entry");
System.out.println("-----------------------");
for (int temp = 0; temp < nList.getLength(); temp++)
{
Node nNode = nList.item(temp);
System.out.println("temp value is: " + temp);
if (nNode.getNodeType() == Node.ELEMENT_NODE)
{
Element eElement = (Element) nNode;
//some piece of code related to arraylist
System.out.println("checking the node number::::::::::: " + temp);
int match_count=0;
//loop around the internal elements and check for equality.
for (int temp1=0; temp1< 25; temp1++)
{
//some piece of code to validate data
}
//if the count is 25, it means it has not broken due to inequality in between and thus return the authorizer in that particular node.
if (match_count == 25){
//some piece of code for more validation
}
else{
System.out.println("This combination is not supported");
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("array list in end is: " + list1);
} finally {
System.out.println("in final block");
}
}
private static String getTagValue(String sTag, Element eElement) {
NodeList nlList = ((org.w3c.dom.Document) eElement).getElementsByTagName(sTag).item(0).getChildNodes();
Node nValue = (Node) nlList.item(0);
return nValue.getNodeValue();
}
}
当我将它作为普通的 java 代码运行时，此代码工作正常。但是，如果我将相同的 java 代码放在 servlet 中，则这行代码会出现以下错误： Element eElement = (Element) nNode;
INFO: Server startup in 744 ms
Routing Parser is accessible
i reached servlet
i reached servlet
Root element :Data
-----------------------
temp value is: 0
java.lang.ClassCastException: com.sun.org.apache.xerces.internal.dom.DeferredElementImpl cannot be cast to javax.lang.model.element.Element
at RoutingParser.doGet(RoutingParser.java:116)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:734)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:563)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:403)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:301)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:162)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:140)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:309)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
array list in end is: []
in final block
有人可以帮我解决这个问题吗？我被困住了，无法继续。
提前致谢。