com.google.gwt.sample.gwtguestbook.client.GuestSignaturePanel.java Source code

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Here is the source code for com.google.gwt.sample.gwtguestbook.client.GuestSignaturePanel.java

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/*
 * Copyright 2009 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.sample.gwtguestbook.client;

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.Composite;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.TextBox;

import java.util.ArrayList;
import java.util.List;

/**
 * Guest signature widget class, containing the components needed to sign the
 * guestbook.
 */
public class GuestSignaturePanel extends Composite implements ClickHandler, FiresEntryUpdates {
    private final HorizontalPanel guestSignaturePanel;
    private final TextBox guestNameBox;
    private final Label guestNameLabel;
    private final TextBox guestMessageBox;
    private final Label guestMessageLabel;
    private final Button signButton;
    private boolean guestSignatureError = false;

    /* Register for entry update handlers listening for guest signatures */
    private List<EntryUpdateHandler> entryUpdateHandlers;

    /**
     * Creates a guest signature panel, with components fully instantiated and
     * attached. 
     * 
     */
    public GuestSignaturePanel() {
        entryUpdateHandlers = new ArrayList<EntryUpdateHandler>();
        guestSignaturePanel = new HorizontalPanel();

        // Create guest signature panel widgets
        guestNameBox = new TextBox();
        guestMessageBox = new TextBox();
        guestNameLabel = new Label("Your Name:");
        guestMessageLabel = new Label("Message:");
        signButton = new Button("Sign!");

        // Set up the widget guest signature panel widget styles (additional to
        // standard styles)
        guestNameLabel.addStyleName("gb-Label");
        guestMessageLabel.addStyleName("gb-Label");
        guestNameBox.addStyleName("gb-NameBox");
        guestMessageBox.addStyleName("gb-MessageBox");

        // Attach components together
        guestSignaturePanel.add(guestNameLabel);
        guestSignaturePanel.add(guestNameBox);
        guestSignaturePanel.add(guestMessageLabel);
        guestSignaturePanel.add(guestMessageBox);
        guestSignaturePanel.add(signButton);

        signButton.addClickHandler(this);

        /* The initWidget(Widget) method inherited from the Composite class must be
         * called exactly once in the constructor to declare the widget that this 
         * composite class is wrapping. */
        initWidget(guestSignaturePanel);
    }

    /**
     * Listens for the guest entry update event, and persists the guest entry
     */
    @Override
    public void onClick(ClickEvent event) {
        if ("".equals(guestNameBox.getText()) || "".equals(guestMessageBox.getText())) {
            guestSignatureError = true;
            fireUpdateError("Please make sure you've filled in all fields");
        } else {
            // Make the entry
            GuestbookEntryTransferObject entry = new GuestbookEntryTransferObject(guestNameBox.getText(),
                    guestMessageBox.getText());
            GuestServiceAsync guestService = (GuestServiceAsync) GWT.create(GuestService.class);
            guestService.addGuestEntry(entry, new AsyncCallback<List<GuestbookEntryTransferObject>>() {
                @Override
                public void onFailure(Throwable caught) {
                    fireUpdateError("Failed to add new entry to guest book");
                }

                @Override
                public void onSuccess(List<GuestbookEntryTransferObject> result) {
                    // Fire an update
                    fireUpdate(result);
                }
            });
        }
    }

    /**
     * Fires an update error and passes the error message to all registered update
     * handlers
     * 
     * @param errorMessage the error message to pass on
     */
    protected void fireUpdateError(String errorMessage) {
        for (EntryUpdateHandler handler : entryUpdateHandlers) {
            handler.updateError(errorMessage);
        }
    }

    /**
     * Fires an update and passes the entries to all registered update handlers
     * 
     * @param entries the latest guest entries to be displayed
     */
    protected void fireUpdate(List<GuestbookEntryTransferObject> entries) {
        for (EntryUpdateHandler handler : entryUpdateHandlers) {
            // Signal that any previous sign in errors are now cleared to all
            // registered handlers
            if (guestSignatureError) {
                handler.clearError();
                guestSignatureError = false;
            }

            handler.updateEntries(entries);
        }
    }

    @Override
    public void addEntryUpdateHandler(EntryUpdateHandler handler) {
        entryUpdateHandlers.add(handler);
    }

    @Override
    public void removeEntryUpdateHandler(EntryUpdateHandler handler) {
        entryUpdateHandlers.remove(handler);
    }
}