Problem with Google Calendar API invocation at server side

Question

Hi guys, I have problems with the invocation of the Google Calendar API at the server side (servlet) with Google Web Toolkit. I downloaded the library for java and I added as external JAR in eclipse the following files: gdata-core, gdata-calendar, gdata- calendar-meta, gdata-client-meta, gdata-client. Then, I created a the method as it follows:

import com.google.gdata.client.calendar.CalendarService;
import com.google.gdata.data.calendar.CalendarEntry;
import com.google.gdata.data.calendar.CalendarFeed;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;



public class GCalServImpl extends RemoteServiceServlet implements
GCalServ {

    @Override
    public String RetrieveCalendars() {
        // TODO Auto-generated method stub
        // Create a CalenderService and authenticate
        try{
        CalendarService myService = new CalendarService("taskR");
        myService.setUserCredentials(***username***, "***password***");

        // Send the request and print the response
        URL feedUrl = new URL("http://www.google.com/calendar/feeds/default/
allcalendars/full");
        CalendarFeed resultFeed = myService.getFeed(feedUrl,
CalendarFeed.class);
        System.out.println("Your calendars:");
        System.out.println();
        String s = "";
        for (int i = 0; i < resultFeed.getEntries().size(); i++) {
          CalendarEntry entry = resultFeed.getEntries().get(i);
          s=entry.getTitle().getPlainText();
          System.out.println("\t" + s);
          return s;
        }
        }catch(Exception e){
            e.printStackTrace();

        }
        return null;
    }

I then call it from the client side doing a basic async invocation. If I try to launch the program I got the following errors:

WARNING: Error for /taskr/cal
java.lang.NoClassDefFoundError: com/google/gdata/client/calendar/
CalendarService
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2389)
    at java.lang.Class.getConstructor0(Class.java:2699)
    at java.lang.Class.newInstance0(Class.java:326)
    at java.lang.Class.newInstance(Class.java:308)
    at org.mortbay.jetty.servlet.Holder.newInstance(Holder.java:153)
    at
org.mortbay.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:
428)
    at
org.mortbay.jetty.servlet.ServletHolder.getServlet(ServletHolder.java:
339)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:
487)
    at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1166)
    at
com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:
51)
    at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1157)
    at
com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:
43)
    at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1157)
    at
com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:
122)
    at org.mortbay.jetty.servlet.ServletHandler
$CachedChain.doFilter(ServletHandler.java:1157)
    at
org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:
388)
    at
org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:
216)
    at
org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:
182)
    at
org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:
765)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:
418)
    at
com.google.apphosting.utils.jetty.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:
70)
    at
org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:
152)
    at com.google.appengine.tools.development.JettyContainerService
$ApiProxyHandler.handle(JettyContainerService.java:349)
    at
org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:
152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:
542)
    at org.mortbay.jetty.HttpConnection
$RequestHandler.content(HttpConnection.java:938)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
    at
org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:
409)
    at org.mortbay.thread.QueuedThreadPool
$PoolThread.run(QueuedThreadPool.java:582)
Caused by: java.lang.ClassNotFoundException:
com.google.gdata.client.calendar.CalendarService
    at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:315)
    at
com.google.appengine.tools.development.IsolatedAppClassLoader.loadClass(IsolatedAppClassLoader.java:
151)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:250)
    at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:398)
    ... 33 more

What can I do??

EDIT: I use google web toolkit and its standard RPC pattern.

Answer 1

You've added the jar files in Eclipse, but it looks like you haven't configured Jetty to find them - that's why you're getting a NoClassDefFoundError.