java - GWT 设计器不起作用

Question

我正在使用:

Eclipse 开普勒 4.3JDK 7GWT 兼容 eclipse 4.3(通过市场下载)GWT版本是通过GWT市场下载的，默认为2.6.0在eclipse上java编译器版本是1.7这不是一个 Maven 项目

当我尝试打开 GWT EntryPoint 类(即 UI)时，它会抛出以下错误:

EntryPoint 类(创建新 GWT 项目时由 eclipse 默认创建的类):

package xsdf.com.client;

import xsdf.com.shared.FieldVerifier;

/**
 * Entry point classes define <code>onModuleLoad()</code>.
 */
public class Xxwa implements EntryPoint {
    /**
     * The message displayed to the user when the server cannot be reached or
     * returns an error.
     */
    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 GreetingServiceAsync greetingService = GWT
            .create(GreetingService.class);

    /**
     * This is the entry point method.
     */
    public void onModuleLoad() {
        final Button sendButton = new Button("Send");
        final TextBox nameField = new TextBox();
        nameField.setText("GWT User");
        final Label errorLabel = new Label();

        // We can add style names to widgets
        sendButton.addStyleName("sendButton");

        // Add the nameField and sendButton to the RootPanel
        // Use RootPanel.get() to get the entire body element
        RootPanel.get("nameFieldContainer").add(nameField);
        RootPanel.get("sendButtonContainer").add(sendButton);
        RootPanel.get("errorLabelContainer").add(errorLabel);

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

        // Create the popup dialog box
        final DialogBox dialogBox = new DialogBox();
        dialogBox.setText("Remote Procedure Call");
        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>Sending name to the server:</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, KeyUpHandler {
            /**
             * Fired when the user clicks on the sendButton.
             */
            public void onClick(ClickEvent event) {
                sendNameToServer();
            }

            /**
             * Fired when the user types in the nameField.
             */
            public void onKeyUp(KeyUpEvent event) {
                if (event.getNativeKeyCode() == KeyCodes.KEY_ENTER) {
                    sendNameToServer();
                }
            }

            /**
             * Send the name from the nameField to the server and wait for a response.
             */
            private void sendNameToServer() {
                // First, we validate the input.
                errorLabel.setText("");
                String textToServer = nameField.getText();
                if (!FieldVerifier.isValidName(textToServer)) {
                    errorLabel.setText("Please enter at least four characters");
                    return;
                }

                // Then, we send the input to the server.
                sendButton.setEnabled(false);
                textToServerLabel.setText(textToServer);
                serverResponseLabel.setText("");
                greetingService.greetServer(textToServer,
                        new AsyncCallback<String>() {
                            public void onFailure(Throwable caught) {
                                // Show the RPC error message to the user
                                dialogBox
                                        .setText("Remote Procedure Call - Failure");
                                serverResponseLabel
                                        .addStyleName("serverResponseLabelError");
                                serverResponseLabel.setHTML(SERVER_ERROR);
                                dialogBox.center();
                                closeButton.setFocus(true);
                            }

                            public void onSuccess(String result) {
                                dialogBox.setText("Remote Procedure Call");
                                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);
        nameField.addKeyUpHandler(handler);
    }
}

当我尝试使用GWT Designer打开上述类时出现错误:

 Internal Error
encountered unexpected internal error. 

This could be caused by a bug or by a misconfiguration issue, conflict, partial update, etc.

java.lang.NoSuchMethodError: com.google.gwt.dev.cfg.ModuleDefLoader.loadFromClassPath(Lcom/google/gwt/core/ext/TreeLogger;Ljava/lang/String;Z)Lcom/google/gwt/dev/cfg/ModuleDef;



Show stack trace. 
Hide stack trace. 

Stack trace:
java.lang.NoSuchMethodError: com.google.gwt.dev.cfg.ModuleDefLoader.loadFromClassPath(Lcom/google/gwt/core/ext/TreeLogger;Ljava/lang/String;Z)Lcom/google/gwt/dev/cfg/ModuleDef;
    at com.google.gwt.dev.shell.designtime.HostedModeSupportImpl.loadModule(HostedModeSupportImpl.java:85)
    at com.google.gwt.dev.shell.designtime.HostedModeSupportImpl.createModuleSpaceHost(HostedModeSupportImpl.java:64)
    at sun.reflect.NativeMetho

我已经检查了可能存在的问题:

如果使用 GWT Designer 遇到 NoSuchMethodError 或 NoClassDefFoundError 我该怎么办？

https://developers.google.com/web-toolkit/tools/gwtdesigner/faq#NoSuchMethodError

我已经尝试过不同的虚拟机，1.8、1.6；

GWT Designer 仍然有效吗？设计 UI 是更好的选择吗？如何纠正这个错误并使GWT Designer正常工作？

Answer 1

GWT Designer 未维护。它不适用于 GWT 2.6.0 或 2.7，并且可能不适用于较新的版本。虽然它确实适用于 2.6.1，但我不建议使用最新版本以外的任何其他版本，特别是“经典”DevMode 也已被弃用:2.7 是 SuperDevMode 真正可用的第一个版本，并且它将继续在未来的版本中进行改进。