Can a servlet extends another servlet?

Ying Su Wed, 13 Mar 2002 18:26:22 -0800

Dear all,

I wrote a servlet "Test.java" which contains a service(request,response) method, and it works properly. Then I want to write another servlet "Handler.java" which extends the "Test" class, and in Handler.java, I overrides the service(request,response) method. It was compiled succesfully,but can not run. I use JBuilder to run my servlets, and it gives the following error:

Error: 500 Location: /servlet/Handler

Internal Servlet Error:java.lang.NullPointerException
at java.lang.ClassLoader.resolveClass0(Native Method)
at java.lang.ClassLoader.resolveClass(ClassLoader.java:588)
at org.apache.tomcat.loader.AdaptiveClassLoader.loadClass(AdaptiveClassLoader.java:430)
at org.apache.tomcat.loader.AdaptiveServletLoader.loadClass(AdaptiveServletLoader.java:174)
at org.apache.tomcat.core.ServletWrapper.loadServlet(ServletWrapper.java:265)
at org.apache.tomcat.core.ServletWrapper.init(ServletWrapper.java:289)
at org.apache.tomcat.core.Handler.service(Handler.java:254)
at org.apache.tomcat.core.ServletWrapper.service(ServletWrapper.java:372)
at org.apache.tomcat.core.ContextManager.internalService(ContextManager.java:812)
at org.apache.tomcat.core.ContextManager.service(ContextManager.java:758)
at org.apache.tomcat.service.http.HttpConnectionHandler.processConnection(HttpConnectionHandler.java:213)
at org.apache.tomcat.service.TcpWorkerThread.runIt(PoolTcpEndpoint.java:416)
at org.apache.tomcat.util.ThreadPool$ControlRunnable.run(ThreadPool.java:501)
at java.lang.Thread.run(Thread.java:484)

Can anyone answer my question? Thanks a lot!

My Test.java:

import java.io.*;
import java.net.*;
import java.text.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class Test extends HttpServlet {

    public void service(HttpServletRequest request, HttpServletResponse response)
        throws IOException,ServletException
    {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<html>");
        out.println("<body>");
        out.println("<head>");
        out.println("<title>Hello World!</title>");
        out.println("</head>");
        out.println("<body>");
        out.println("<h1>Hello World!</h1>");

        onMessage(request,response);
        out.println("</body>");
        out.println("</html>");
    }
public void onMessage(HttpServletRequest request, HttpServletResponse response)
  throws IOException,ServletException
{
          PrintWriter out = response.getWriter();
          out.println("<h1>onMessage?</h1>");
}
}

My Handler.java

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class EbXMLHandler extends EbTest {

    public void service(HttpServletRequest request, HttpServletResponse response)throws IOException,ServletException
    {
        super.service(request,response);
    }
}

best regards!

Sincerely

Ying

Can a servlet extends another servlet?

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