GWT app new branch

google-web-toolkit/src/main/java/com/baeldung/Google_web_toolkit.gwt.xml

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  When updating your version of GWT, you should also update this DTD reference,
+  so that your app can take advantage of the latest GWT module capabilities.
+-->
+<!DOCTYPE module PUBLIC "-//Google Inc.//DTD Google Web Toolkit 2.8.2//EN"
+  "http://gwtproject.org/doctype/2.8.2/gwt-module.dtd">
+<module rename-to='google_web_toolkit'>
+  <!-- Inherit the core Web Toolkit stuff.                        -->
+  <inherits name='com.google.gwt.user.User'/>
+
+  <!-- Inherit the default GWT style sheet.  You can change       -->
+  <!-- the theme of your GWT application by uncommenting          -->
+  <!-- any one of the following lines.                            -->
+  <inherits name='com.google.gwt.user.theme.clean.Clean'/>
+  <!-- <inherits name='com.google.gwt.user.theme.standard.Standard'/> -->
+  <!-- <inherits name='com.google.gwt.user.theme.chrome.Chrome'/> -->
+  <!-- <inherits name='com.google.gwt.user.theme.dark.Dark'/>     -->
+
+  <!-- Other module inherits                                      -->
+
+  <!-- Specify the app entry point class.                         -->
+  <entry-point class='com.baeldung.client.Google_web_toolkit'/>
+
+  <!-- Specify the paths for translatable code                    -->
+  <source path='client'/>
+  <source path='shared'/>
+
+  <!-- allow Super Dev Mode -->
+  <add-linker name="xsiframe"/>
+</module>

google-web-toolkit/src/main/java/com/baeldung/client/Google_web_toolkit.java

@@ -0,0 +1,108 @@
+package com.baeldung.client;
+
+import com.baeldung.shared.MessageService;
+import com.baeldung.shared.MessageServiceAsync;
+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;
+
+/**
+ * Entry point classes define <code>onModuleLoad()</code>.
+ */
+public class Google_web_toolkit implements EntryPoint {
+    private final MessageServiceAsync messageServiceAsync = GWT.create(MessageService.class);
+
+    public void onModuleLoad() {
+        Button sendButton = new Button("Submit");
+        TextBox nameField = new TextBox();
+        nameField.setText("Hi there");
+
+        Label warningLabel = new Label();
+
+        sendButton.addStyleName("sendButton");
+
+        RootPanel.get("nameFieldContainer").add(nameField);
+        RootPanel.get("sendButtonContainer").add(sendButton);
+        RootPanel.get("errorLabelContainer").add(warningLabel);
+
+        Button closeButton = new Button("Thanks");
+        closeButton.getElement().setId("closeButton");
+
+        Label textToServerLabel = new Label();
+        HTML serverResponseLabel = new HTML();
+        VerticalPanel vPanel = new VerticalPanel();
+        vPanel.addStyleName("vPanel");
+        vPanel.add(new HTML("Sending message to the server:"));
+        vPanel.add(textToServerLabel);
+        vPanel.add(new HTML("<br><b>Server replies:</b>"));
+        vPanel.add(serverResponseLabel);
+        vPanel.setHorizontalAlignment(VerticalPanel.ALIGN_RIGHT);
+        vPanel.add(closeButton);
+        vPanel.setVisible(false);
+        RootPanel.get("serverResponseContainer").add(vPanel);
+
+        closeButton.addClickHandler(event -> {
+            sendButton.setEnabled(true);
+            sendButton.setFocus(true);
+            vPanel.setVisible(false);
+        });
+
+        class MyHandler implements ClickHandler, KeyUpHandler {
+
+            public void onClick(ClickEvent event) {
+                sendMessageToServer();
+            }
+
+            public void onKeyUp(KeyUpEvent event) {
+                if (event.getNativeKeyCode() == KeyCodes.KEY_ENTER) {
+                    sendMessageToServer();
+                }
+            }
+
+            private void sendMessageToServer() {
+
+                warningLabel.setText("");
+                String textToServer = nameField.getText();
+                if (textToServer == null || textToServer.isEmpty()) {
+                    warningLabel.setText("Please enter the message");
+                    return;
+                }
+
+                sendButton.setEnabled(false);
+                textToServerLabel.setText(textToServer);
+                serverResponseLabel.setText("");
+                messageServiceAsync.sendMessage(textToServer, new AsyncCallback<String>() {
+                    public void onFailure(Throwable caught) {
+                        serverResponseLabel.addStyleName("serverResponseLabelError");
+                        serverResponseLabel.setHTML("server error occurred");
+                        closeButton.setFocus(true);
+                    }
+
+                    public void onSuccess(String result) {
+                        serverResponseLabel.removeStyleName("serverResponseLabelError");
+                        serverResponseLabel.setHTML(result);
+                        closeButton.setFocus(true);
+                        vPanel.setVisible(true);
+                    }
+                });
+            }
+        }
+
+        // Add a handler to send the name to the server
+        MyHandler handler = new MyHandler();
+        sendButton.addClickHandler(handler);
+        nameField.addKeyUpHandler(handler);
+    }
+}

google-web-toolkit/src/main/java/com/baeldung/server/MessageServiceImpl.java

@@ -0,0 +1,22 @@
+package com.baeldung.server;
+
+import com.baeldung.shared.MessageService;
+import com.google.gwt.user.server.rpc.RemoteServiceServlet;
+
+import java.time.LocalDateTime;
+
+/**
+ * The server-side implementation of the RPC service.
+ */
+@SuppressWarnings("serial")
+public class MessageServiceImpl extends RemoteServiceServlet implements MessageService {
+
+    public String sendMessage(String message) throws IllegalArgumentException {
+        if (message == null) {
+            throw new IllegalArgumentException("message is null");
+        }
+
+        return "Hello, " + message + "!<br><br> Time received: " + LocalDateTime.now();
+    }
+
+}

google-web-toolkit/src/main/java/com/baeldung/shared/MessageService.java

@@ -0,0 +1,12 @@
+package com.baeldung.shared;
+
+import com.google.gwt.user.client.rpc.RemoteService;
+import com.google.gwt.user.client.rpc.RemoteServiceRelativePath;
+
+/**
+ * The client-side stub for the RPC service.
+ */
+@RemoteServiceRelativePath("greet")
+public interface MessageService extends RemoteService {
+    String sendMessage(String message) throws IllegalArgumentException;
+}

google-web-toolkit/src/main/java/com/baeldung/shared/MessageServiceAsync.java

@@ -0,0 +1,10 @@
+package com.baeldung.shared;
+
+import com.google.gwt.user.client.rpc.AsyncCallback;
+
+/**
+ * The async counterpart of <code>MessageService</code>.
+ */
+public interface MessageServiceAsync {
+    void sendMessage(String input, AsyncCallback<String> callback) throws IllegalArgumentException;
+}