Java tutorial
/* * Copyright [2013] [Cloud4SOA, www.cloud4soa.eu] * * * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 eu.cloud4soa.gwt.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.event.dom.client.KeyCodes; import com.google.gwt.event.dom.client.KeyUpEvent; import com.google.gwt.event.dom.client.KeyUpHandler; 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 eu.cloud4soa.gwt.shared.FieldVerifier; /** * Entry point classes define <code>onModuleLoad()</code>. */ public class Application 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("Try UC9 Sequence"); final TextBox nameField = new TextBox(); nameField.setText("webapp"); 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 application 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); } }