HelloServlet.java

package hello.web;

import java.io.IOException;
import java.util.Date;
import java.util.Properties;
import javax.naming.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.rmi.PortableRemoteObject;
import hello.ejb.Hello;
import hello.ejb.HelloHome;

public class HelloServlet extends HttpServlet {

   // constructor
   public HelloServlet() {
      super();
      trace("<init>");
   }

   // A reference to the remote `Hello' object
   protected Hello _hello;

   // Initializes this servlet
   public void init(ServletConfig config) throws ServletException {
      super.init(config);
      trace("init");

      // Get the initial JNDI context using our settings
      Context context;
      try {
         context = new InitialContext();
      }
      catch (Throwable exception) {
         throw new ServletException(
            "Unable to get initial JNDI context: " + exception.toString());
      }

      // Get a reference to the Hello home interface
      HelloHome helloHome;
      try {
         Object boundObject = context.lookup("java:comp/env/ejb/HelloHome");
         helloHome = (HelloHome) PortableRemoteObject.narrow(boundObject,
                                                             HelloHome.class);
      }
      catch (Throwable exception) {
         throw new ServletException(
            "Unable to get home interface: " + exception.toString());
      }

      // Get a reference to a Hello instance
      try {
         _hello = helloHome.create();
      }
      catch (Throwable exception) {
         throw new ServletException(
            "Unable to create Hello instance: " + exception.toString());
      }

      // Insanity check: Make sure we have a valid reference
      if (_hello == null) {
         throw new ServletException(
            "Unable to create Hello instance, create() returned null");
      }
   }

   // Handles the HTTP GET request
   public void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
      trace("doGet");

      ServletOutputStream out = response.getOutputStream();

      response.setContentType("text/html");

      // Get the answer from the bean
      String answer;
      try {
         answer = _hello.sayHello();
      }
      catch (Throwable exception) {
         out.println("<HTML><BODY bgcolor=\"#FFFFFF\">");
         out.println("Time stamp: " + new Date().toString());
         out.println("<BR>Hello type: " + _hello.getClass().getName());
         out.println("Error calling the Hello bean");
         out.println(exception.toString());
         out.println("</BODY>");
         out.println("</HTML>");
         return;
      }

      out.println("<HTML><BODY bgcolor=\"#FFFFFF\">");
      out.println("Time stamp: " + new Date().toString());
      out.println("<BR>Hello type: " + _hello.getClass().getName());
      out.println("<BR>Answer: " + answer);
      out.println("</BODY>");
      out.println("</HTML>");
   }

   // Displays a trace message to System.out
   private void trace(String methodName) {
      System.out.print(methodName);
      System.out.println("() called");
   }

}