Hibernate exception while using GWT

Question

I'm using a very simple GWT class, that sends a String to the server, then the server sends this to a hibernate session and adds the field to a database, relatively simple stuff.

My code is as follows...

public class GreetingServiceImpl extends RemoteServiceServlet implements
    GreetingService {

public String greetServer(String input) throws IllegalArgumentException {
    // Verify that the input is valid. 
    if (!FieldVerifier.isValidName(input)) {
        // If the input is not valid, throw an IllegalArgumentException back to
        // the client.
        throw new IllegalArgumentException(
                "Name must be at least 4 characters long");
    }

    // Escape data from the client to avoid cross-site script vulnerabilities.
    input = escapeHtml(input);
    User user = new User();
    user.setFirstName(input);
    DaoFactory factory = new DaoFactory();
    try {
        factory.create(user);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return "User : " + input + " added";
}

/**
 * Escape an html string. Escaping data received from the client helps to
 * prevent cross-site script vulnerabilities.
 * 
 * @param html the html string to escape
 * @return the escaped string
 */
private String escapeHtml(String html) {
    if (html == null) {
        return null;
    }
    return html.replaceAll("&", "&amp;").replaceAll("<", "&lt;")
            .replaceAll(">", "&gt;");
}

This is where it looks like it exceptions, when I run my app, all works fine until I click the button that invokes this method and I get the following exception...

    [ERROR] javax.servlet.ServletContext log: Exception while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract java.lang.String com.behaviour.app.client.GreetingService.greetServer(java.lang.String) throws java.lang.IllegalArgumentException' threw an unexpected exception: java.lang.NoClassDefFoundError: org/hibernate/Session
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:385)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:588)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:208)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:248)
    at com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:62)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:35)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:58)
    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$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.BackendServersFilter.doFilter(BackendServersFilter.java:97)
    at org.mortbay.jetty.servlet.ServletHandler$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$ApiProxyHandler.handle(JettyContainerService.java:351)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
    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.NoClassDefFoundError: org/hibernate/Session
    at com.behaviour.app.server.GreetingServiceImpl.greetServer(GreetingServiceImpl.java:29)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:616)
    at com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime.java:100)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:569)
    ... 34 more
Caused by: java.lang.ClassNotFoundException: org.hibernate.Session
    at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
    at com.google.appengine.tools.development.IsolatedAppClassLoader.loadClass(IsolatedAppClassLoader.java:176)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
    ... 41 more

Does anyone have any ideas as to what I'm doing wrong? My hibernate class is shown below...

package com.behaviour.beans;

import javax.persistence.Column;

@Entity
public class User {

    private int userId;
    private String firstName;
    private String lastName;


    @Id
    @Column(name = "userid", nullable = false)
    @GeneratedValue(strategy=GenerationType.AUTO)
    public int getUserId() {
        return userId;
    }
    public void setUserId(int userId) {
        this.userId = userId;
    }

    @Column(name = "firstname", nullable = true)
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    @Column(name = "surname", nullable = true)
    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

}

Thanks,

Augusto · Accepted Answer · 2011-08-22 10:40:35Z

2

The problem is not in the code, but that the Hibernate jar is missing. In particular, the application cannot find the class org.hibernate.Session.

answered Aug 22, 2011 at 10:40

Augusto

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4 Comments

David Over a year ago

hmm, this doesn't appear to be the case as if I run a test class with just User user = new User(); user.setFirstName(input); DaoFactory factory = new DaoFactory(); and then commit the user, it works fine, so it's not missing the jar

Augusto Over a year ago

You probably don't get the error on your unit tests because the classpath is different. The error is very, very clear, java cannot find the Session class.

David Over a year ago

It's not on a unit test class, it's an actual class in the same package that uses the same classpath.

David Over a year ago

Ah, it was because the libs were in the classpath and build path, but not in the WEB-INF for GWT, thank you.

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