com.google.gwt.examples.HistoryExample.java Source code

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Here is the source code for com.google.gwt.examples.HistoryExample.java

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/*
 * Copyright 2006 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.examples;

import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.event.logical.shared.ValueChangeEvent;
import com.google.gwt.event.logical.shared.ValueChangeHandler;
import com.google.gwt.user.client.History;
import com.google.gwt.user.client.ui.Hyperlink;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.VerticalPanel;

public class HistoryExample implements EntryPoint, ValueChangeHandler<String> {

    private Label lbl = new Label();

    public void onModuleLoad() {
        // Create three hyperlinks that change the application's history.
        Hyperlink link0 = new Hyperlink("link to foo", "foo");
        Hyperlink link1 = new Hyperlink("link to bar", "bar");
        Hyperlink link2 = new Hyperlink("link to baz", "baz");

        // If the application starts with no history token, redirect to a new
        // 'baz' state.
        String initToken = History.getToken();
        if (initToken.length() == 0) {
            History.newItem("baz");
        }

        // Add widgets to the root panel.
        VerticalPanel panel = new VerticalPanel();
        panel.add(lbl);
        panel.add(link0);
        panel.add(link1);
        panel.add(link2);
        RootPanel.get().add(panel);

        // Add history listener
        History.addValueChangeHandler(this);

        // Now that we've setup our listener, fire the initial history state.
        History.fireCurrentHistoryState();
    }

    public void onValueChange(ValueChangeEvent<String> event) {
        // This method is called whenever the application's history changes. Set
        // the label to reflect the current history token.
        lbl.setText("The current history token is: " + event.getValue());
    }
}