java - GWT:在服务器端获取 java.lang.NoClassDefFoundError

Question

我正在使用 GWT2.6。在我的 gwt 服务器端，我试图实例化一个来自另一个 eclipse 项目的类。我将该项目添加到我的“Java 构建路径”中。但是我仍然遇到 java.lang.NoClassDefFoundError 问题。

我的代码和错误消息粘贴在下面。

Server: initialize and run
Jan 22, 2015 5:53:22 PM com.google.appengine.tools.development.ApiProxyLocalImpl log
SEVERE: javax.servlet.ServletContext log: Exception while dispatching incoming RPC call
com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract java.util.List com.algorithmics.mdc.client.OnboardingToolService.getProducts()' threw an unexpected exception: java.lang.NoClassDefFoundError: com/algorithmics/datamart/dmob/app/DMOBApp
    at com.google.gwt.user.server.rpc.RPC.encodeResponseForFailure(RPC.java:389)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:579)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:265)
    at com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:305)
    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$CachedChain.doFilter(ServletHandler.java:1166)
    at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:127)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:63)
    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:125)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
    at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:366)
    at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:349)
    at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:116)
    at org.mortbay.jetty.servlet.ServletHandler$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.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:98)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:491)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
    at org.mortbay.jetty.Server.handle(Server.java:326)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
    at org.mortbay.jetty.HttpConnection$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.NoClassDefFoundError: com/algorithmics/datamart/dmob/app/DMOBApp
    at com.algorithmics.mdc.server.OnboardingToolServiceImpl.getProducts(OnboardingToolServiceImpl.java:28)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.google.appengine.tools.development.agent.runtime.Runtime.invoke(Runtime.java:115)
    at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:561)
    ... 40 more
Caused by: java.lang.ClassNotFoundException: com.algorithmics.datamart.dmob.app.DMOBApp
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at com.google.appengine.tools.development.IsolatedAppClassLoader.loadClass(IsolatedAppClassLoader.java:216)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 47 more

我的代码:

public class OnboardingToolServiceImpl extends RemoteServiceServlet implements OnboardingToolService  {

    private String[] dmobArgs;

    private void initializeDmob(){
        dmobArgs = new String[]{"-U", "xx", "-P", "xx1234", "-S", "default", "-R", "suite-test", "-c", "c:\\xx\\xx\\xx\\cfg\\ConfigServer.cfg", "-o", "list"};
    }

    @Override
    public List<ProductDefinition> getProducts() {
        System.out.println("Server: dmobArgs");
        DMOBApp.main(dmobArgs);     //dmobArgs
        System.out.println("Server: done");
        List list = new LinkedList();

        ProductDefinition stock = new ProductDefinition("stock","xx","aa","","","","");
        ProductDefinition cash = new ProductDefinition("cash","xx","aa","","","","");
        ProductDefinition bond = new ProductDefinition("bond","xx","aa","","","","");
        ProductDefinition stock1 = new ProductDefinition("stock1","xx","aa","","","","");
        ProductDefinition stock2 = new ProductDefinition("stock2","xx","aa","","","","");
        ProductDefinition cash1 = new ProductDefinition("cash1","xx","aa","","","","");
        list.add(stock);
        list.add(cash);
        list.add(bond);
        return list;
    }
}

Answer 1

将其添加到构建路径中是不够的。您还必须将它添加到 /WEB-INF/lib 文件夹。否则，它将在服务器端不可用。

如果您使用 Eclipse，请选择项目并查看 Problems 选项卡。您应该在那里看到一条消息，指出服务器上的资源不可用。右键单击此消息并选择“快速修复”。选择“复制...”选项。