Adding Google Signin feature with GWT and GAE
29 Dec 2012SignOn features using Google Web Services is easy and efficient way to authenticate users. It’s pretty common these days to have authentication via Google UserServices. Google App Engine provides UserServiceFactory api for this purpose. I tried implementing this API within Google Web Toolkit and here’s the code snippet for reference.
The code is divided to Server Side Code and_ Client Side Code_. Server side code provides the implementation of the actual API call while the Client side code provides interface to those RPC calls and you can make asynchronous call to the server side api. Deeper understanding of RPC call can be found in my previous weblogs.
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| package com.aayush.hangman.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.http.client.Request; | |
| import com.google.gwt.http.client.RequestBuilder; | |
| import com.google.gwt.http.client.RequestCallback; | |
| import com.google.gwt.http.client.RequestException; | |
| import com.google.gwt.http.client.Response; | |
| import com.google.gwt.user.client.Random; | |
| import com.google.gwt.user.client.Window; | |
| import com.google.gwt.user.client.rpc.AsyncCallback; | |
| import com.google.gwt.user.client.ui.Button; | |
| import com.google.gwt.user.client.ui.FlowPanel; | |
| import com.google.gwt.user.client.ui.HTML; | |
| import com.google.gwt.user.client.ui.Image; | |
| import com.google.gwt.user.client.ui.Label; | |
| import com.google.gwt.user.client.ui.RootPanel; | |
| public class HangMan implements EntryPoint { | |
| final LoginServicesAsync logininfo = GWT.create(LoginServices.class); | |
| public void onModuleLoad() { | |
| // Create Interface | |
| RootPanel hangman_login = RootPanel.get("signon"); | |
| createloginScreen(hangman_login); | |
| } | |
| private void createloginScreen(final RootPanel hangman_login) { | |
| logininfo.isLoggenIn(new AsyncCallback<Boolean>() { | |
| @Override | |
| public void onFailure(Throwable caught) { | |
| Window.alert("Error : Sorry Cannot Connect to Google Services"); | |
| hangman_login.add(new Label("Cannot Connect to Google Services")); | |
| } | |
| @Override | |
| public void onSuccess(Boolean result) { | |
| if (result) { | |
| getEmail(); | |
| } else { | |
| getsigninurl(); | |
| } | |
| } | |
| private void getsigninurl() { | |
| logininfo.createLoginURL(GWT.getHostPageBaseURL(),new AsyncCallback<String>() { | |
| @Override | |
| public void onSuccess(String result) { | |
| Window.alert(result); | |
| String login_url = "<a href=\" " + result + "\">SignIn</a>"; | |
| hangman_login.add(new HTML(login_url)); | |
| } | |
| @Override | |
| public void onFailure(Throwable caught) { | |
| hangman_login.add(new Label("Cannot Connect to Google Services")); | |
| } | |
| }); | |
| } | |
| private void getEmail() { | |
| logininfo.getEmail(new AsyncCallback<String>() { | |
| @Override | |
| public void onSuccess(String result) { | |
| String userwelcome = "<h4>Welcome, " + result + "</h4>"; | |
| hangman_login.add(new HTML(userwelcome)); | |
| // Get SignOut URL | |
| logininfo.createLogoutURL(GWT.getHostPageBaseURL(), | |
| new AsyncCallback<String>() { | |
| @Override | |
| public void onSuccess(String result) { | |
| String logout = "<a href=\"" + result+ "\">LogOff</a><br><br>"; | |
| hangman_login.add(new HTML(logout)); | |
| } | |
| @Override | |
| public void onFailure(Throwable caught) { | |
| hangman_login.add(new Label("Cannot Connect to Google Services")); | |
| } | |
| }); | |
| } | |
| @Override | |
| public void onFailure(Throwable caught) { | |
| Window.alert("Cannot Perform RPC Call"); | |
| hangman_login.add(new Label("Cannot Connect to Google Services")); | |
| } | |
| }); | |
| } | |
| }); | |
| } |
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| package com.aayush.hangman.client; | |
| import com.google.gwt.user.client.rpc.RemoteService; | |
| import com.google.gwt.user.client.rpc.RemoteServiceRelativePath; | |
| @RemoteServiceRelativePath("loginservices") | |
| public interface LoginServices extends RemoteService{ | |
| String createLoginURL( String callbackURL ); | |
| String createLogoutURL ( String callbackURL ); | |
| String getEmail(); | |
| boolean isLoggenIn(); | |
| } |
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| package com.aayush.hangman.client; | |
| import com.google.gwt.user.client.rpc.AsyncCallback; | |
| public interface LoginServicesAsync { | |
| void createLoginURL(String callbackURL, AsyncCallback<String> callback); | |
| void createLogoutURL(String callbackURL, AsyncCallback<String> callback); | |
| void getEmail(AsyncCallback<String> callback); | |
| void isLoggenIn(AsyncCallback<Boolean> callback); | |
| } |
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| package com.aayush.hangman.server; | |
| import com.aayush.hangman.client.LoginServices; | |
| import com.google.appengine.api.users.UserService; | |
| import com.google.appengine.api.users.UserServiceFactory; | |
| import com.google.gwt.user.server.rpc.RemoteServiceServlet; | |
| @SuppressWarnings("serial") | |
| public class LoginServicesImpl extends RemoteServiceServlet implements LoginServices{ | |
| final static public UserService userService = UserServiceFactory.getUserService(); | |
| @Override | |
| public String createLoginURL(String callbackURL) { | |
| return userService.createLoginURL(callbackURL); | |
| } | |
| @Override | |
| public String createLogoutURL(String callbackURL) { | |
| return userService.createLogoutURL(callbackURL); | |
| } | |
| @Override | |
| public String getEmail() { | |
| return userService.getCurrentUser().getEmail(); | |
| } | |
| @Override | |
| public boolean isLoggenIn() { | |
| return userService.isUserLoggedIn(); | |
| } | |
| } |