Question

我使用GWT创建了一个新的Google应用程序，运行正常。但是，当我单击一个负责与服务器端执行某些操作的按钮时，它会抛出异常错误。请有人可以提供帮助吗？先感谢您：（这是代码：

package com.ukstudentfeedback.client;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.core.client.GWT;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.user.client.rpc.AsyncCallback;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.DialogBox;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.ukstudentfeedback.shared.FieldVerifier;
import com.ukstudentfeedback.client.MailClient;
import com.ukstudentfeedback.client.MailClientAsync;

public class Ukstudentfeedback implements EntryPoint{

    private static final String SERVER_ERROR = "An error occurred while "
            + "attempting to contact the server. Please check your network "
            + "connection and try again.";

    /**
     * Create a remote service proxy to talk to the server-side Greeting service.
     */
    private final MailClientAsync sendMessage = GWT
            .create(MailClient.class);

    // ...
    public void onModuleLoad()
    {
        java.lang.System.out.println("I finally worked!");
        final Button sendButton;
        final TextBox toField, fromField, subjectField, messageField;
        final Label errorLabel = new Label();

        sendButton = new Button("Send");
        toField = new TextBox();
        fromField = new TextBox();
        subjectField = new TextBox();
        messageField = new TextBox();

        sendButton.addStyleName("sendButton");

        toField.setText("Testing");
     // Add the nameField and sendButton to the RootPanel
     // Use RootPanel.get() to get the entire body element
        RootPanel.get("sendButton").add(sendButton);
        RootPanel.get("To").add(toField);
        RootPanel.get("From").add(fromField);
        RootPanel.get("Subject").add(subjectField);
        RootPanel.get("Message").add(messageField);
        RootPanel.get("errorLabelContainer").add(errorLabel);

        // Focus the cursor on the to field when the app loads
                toField.setFocus(true);
                toField.selectAll();

                //sendButton.setEnabled(true);

                // Create the popup dialog box
                final DialogBox dialogBox = new DialogBox();
                dialogBox.setText("Message Sent");
                dialogBox.setAnimationEnabled(true);
                final Button closeButton = new Button("Close");
                // We can set the id of a widget by accessing its Element
                closeButton.getElement().setId("closeButton");
                final Label textToServerLabel = new Label();
                final HTML serverResponseLabel = new HTML();
                VerticalPanel dialogVPanel = new VerticalPanel();
                dialogVPanel.addStyleName("dialogVPanel");
                dialogVPanel.add(new HTML("<b>Message Sent:</b>"));
                dialogVPanel.add(textToServerLabel);
                dialogVPanel.add(new HTML("<br><b>Server replies:</b>"));
                dialogVPanel.add(serverResponseLabel);
                dialogVPanel.setHorizontalAlignment(VerticalPanel.ALIGN_RIGHT);
                dialogVPanel.add(closeButton);
                dialogBox.setWidget(dialogVPanel);

                // Add a handler to close the DialogBox
                closeButton.addClickHandler(new ClickHandler() {
                    public void onClick(ClickEvent event) {
                        dialogBox.hide();
                        sendButton.setEnabled(true);
                        sendButton.setFocus(true);
                    }
                });

    // Create a handler for the sendButton and nameField
    class MyHandler implements ClickHandler{
                /**
                 * Fired when the user clicks on the sendButton.
                 */
                public void onClick(ClickEvent event) {
                    java.lang.System.out.println("I have been clicked");
                    sendMessageToServer();
                }

                public void sendMessageToServer()
                {
                    errorLabel.setText("");
                    String to = toField.getText();
                    String from = fromField.getText();
                    String subject = subjectField.getText();
                    String message = messageField.getText();

                    if (!FieldVerifier.isValidName(to, from, subject, message)) {
                        errorLabel.setText("Please enter at least four characters");
                        return;
                    }


                    sendButton.setEnabled(false);
                    textToServerLabel.setText("Hello");
                    serverResponseLabel.setText("");
                    sendMessage.sendMessage(to, from, subject, message, new AsyncCallback<String>() {
                        public void onFailure(Throwable caught) {
                            // Show the RPC error message to the user
                            dialogBox
                                    .setText("Message sending Failed");
                            serverResponseLabel
                                    .addStyleName("serverResponseLabelError");
                            serverResponseLabel.setHTML(SERVER_ERROR);
                            dialogBox.center();
                            closeButton.setFocus(true);

                        }

                        public void onSuccess(String result) {
                            dialogBox.setText("Message Sent");
                            serverResponseLabel
                                    .removeStyleName("serverResponseLabelError");
                            serverResponseLabel.setHTML(result);
                            dialogBox.center();
                            closeButton.setFocus(true);

                        }
                    });
                }

    }
    // Add a handler to send the name to the server
            MyHandler handler = new MyHandler();
            sendButton.addClickHandler(handler);
    }
}

服务器端：

package com.ukstudentfeedback.server;

import java.io.UnsupportedEncodingException;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

import com.google.gwt.user.server.rpc.RemoteServiceServlet;
import com.ukstudentfeedback.shared.FieldVerifier;

@SuppressWarnings("serial")
public class MailServerImpl extends RemoteServiceServlet{

    public void sendMessage(String to, String from, String subject, String message) throws IllegalArgumentException
    {
        // Verify that no input is null. 
                if (!FieldVerifier.isValidName(to, from, subject, message)) {
                    // If the input is not valid, throw an IllegalArgumentException back to
                    // the client.
                    throw new IllegalArgumentException(
                            "Name must be at least 4 characters long");
                }

        Properties props = new Properties();
        Session session = Session.getDefaultInstance(props, null);

        try 
        {
            Message msg = new MimeMessage(session);
            msg.setFrom(new InternetAddress(from, "Admin"));
            msg.addRecipient(Message.RecipientType.TO,
                             new InternetAddress(to, "Mr. User"));
            msg.setSubject(subject);
            msg.setText(message);
            Transport.send(msg);

        } 
        catch (AddressException e) 
        {
            // ...
            e.printStackTrace();
        } catch (MessagingException e) 
        {
            // ...
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}

错误堆栈：

23:26:55.817 [ERROR] [ukstudentfeedback] Uncaught exception escaped

com.google.gwt.event.shared.UmbrellaException: One or more exceptions caught, see full set in UmbrellaException#getCauses
    at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:129)
    at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:129)
    at com.google.gwt.event.dom.client.DomEvent.fireNativeEvent(DomEvent.java:116)
    at com.google.gwt.user.client.ui.Widget.onBrowserEvent(Widget.java:177)
    at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1351)
    at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1307)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
    at sun.reflect.GeneratedMethodAccessor27.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292)
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546)
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363)
    at java.lang.Thread.run(Thread.java:680)
Caused by: com.google.gwt.user.client.rpc.ServiceDefTarget$NoServiceEntryPointSpecifiedException: Service implementation URL not specified
    at com.google.gwt.user.client.rpc.impl.RemoteServiceProxy.doPrepareRequestBuilderImpl(RemoteServiceProxy.java:430)
    at com.google.gwt.user.client.rpc.impl.RemoteServiceProxy.doInvoke(RemoteServiceProxy.java:368)
    at com.google.gwt.user.client.rpc.impl.RemoteServiceProxy$ServiceHelper.finish(RemoteServiceProxy.java:74)
    at com.ukstudentfeedback.client.MailClient_Proxy.sendMessage(MailClient_Proxy.java:38)
    at com.ukstudentfeedback.client.Ukstudentfeedback$1MyHandler.sendMessageToServer(Ukstudentfeedback.java:118)
    at com.ukstudentfeedback.client.Ukstudentfeedback$1MyHandler.onClick(Ukstudentfeedback.java:98)
    at com.google.gwt.event.dom.client.ClickEvent.dispatch(ClickEvent.java:54)
    at com.google.gwt.event.dom.client.ClickEvent.dispatch(ClickEvent.java:1)
    at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:1)
    at com.google.web.bindery.event.shared.EventBus.dispatchEvent(EventBus.java:40)
    at com.google.web.bindery.event.shared.SimpleEventBus.doFire(SimpleEventBus.java:193)
    at com.google.web.bindery.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:88)
    at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:127)
    at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:129)
    at com.google.gwt.event.dom.client.DomEvent.fireNativeEvent(DomEvent.java:116)
    at com.google.gwt.user.client.ui.Widget.onBrowserEvent(Widget.java:177)
    at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1351)
    at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1307)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
    at sun.reflect.GeneratedMethodAccessor27.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292)
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546)
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363)
    at java.lang.Thread.run(Thread.java:680)

Answer 1

查找UmbrellaException寻找“由...引起”的原因：

Caused by:
  com.google.gwt.user.client.rpc.ServiceDefTarget$NoServiceEntryPointSpecifiedException:
    Service implementation URL not specified

通过执行以下任一操作指定远程服务URL：

向MailClientAsync界面添加RemoteServiceRelativePath注释。

致电ServiceDefTarget#setServiceEntryPoint：

((ServiceDefTarget)sendMessage).
  setServiceEntryPoint("http://www.example.com/service");

GWT Uncaught异常逃脱

1 个答案: