Creating an admin application for phpBB using GWT and JPA

Implement GWT Client

Now we can start implementing the client.

GWT has created a html file AdminApp.html. Let's clean it up a little:

...
   <body>
      <h1>PHPBB Admin</h1>
      <p>
         Administration of users.
      </p>
      <p id="slot1"></p>
   </body>

Create a separate class to hold the login widgets:

public class LoginPanel extends Grid { private Label usernameLabel; private TextBox username; private Label passwordLabel; private PasswordTextBox password; private Button login; public LoginPanel() { super(3, 2); usernameLabel = new Label("Username"); username = new TextBox(); passwordLabel = new Label("Password"); password = new PasswordTextBox(); login = new Button(); login.setText("Login"); setWidget(0, 0, usernameLabel); setWidget(0, 1, username); setWidget(1, 0, passwordLabel); setWidget(1, 1, password); setWidget(2, 1, login); } }

Show that panel in the main module:

public class AdminApp implements EntryPoint {

  /**
   * This is the entry point method.
   */
  public void onModuleLoad() {
     LoginPanel loginPanel = new LoginPanel();
     RootPanel.get("slot1").add(loginPanel);
  }
}

And run:

Remote Procedure Call

Now, we need to connect the client to the server. To do this, we will use GWT RPC.

Create 2 similar interfaces in the com.objectgen.phpbb.client package:

public interface LoginService extends RemoteService {
   UserDTO login(String username, String password);
}

public interface LoginServiceAsync {
   void login(String username, String password, AsyncCallback callback);
}

Then, create an implementation of LoginService in package com.objectgen.phpbb.server. Note how I use Dozer to convert the User object to a UserDTO. The reason is that JPA classes cannot be serialized by GWT, so HiberObjects generates DTO objects that can be used for this purpose. (You can download Dozer from the Download page.)

public class LoginServiceImpl extends RemoteServiceServlet implements LoginService { private transient HibernateHelper persistenceHelper = HibernateHelper.getInstance(); private MapperIF mapper = new DozerBeanMapper(); private UserDAO userDAO = new UserDAO(); public LoginServiceImpl() { } public UserDTO login(final String username, final String password) { javax.persistence.EntityManager entityManager = persistenceHelper.getEntityManager(); EntityTransaction tx = entityManager.getTransaction(); tx.begin(); try { User user = userDAO.login("ADMINISTRATORS", username, password); UserDTO dto = (user != null ? (UserDTO) mapper.map(user, UserDTO.class) : null); tx.commit(); return dto; } catch(RuntimeException e) { e.printStackTrace(); tx.rollback(); throw e; } } }

<servlet path="/login" class="com.objectgen.phpbb.server.LoginServiceImpl"/>

And create an instance of the servlet in our main module:

public class AdminApp implements EntryPoint { // Defined in AdminApp.gwt.xml private static final String LOGIN_SERVICE = "login"; /** * This is the entry point method. */ public void onModuleLoad() { LoginServiceAsync loginService = (LoginServiceAsync) GWT.create(LoginService.class); ServiceDefTarget loginEndpoint = (ServiceDefTarget) loginService; loginEndpoint.setServiceEntryPoint(GWT.getModuleBaseURL() + LOGIN_SERVICE); LoginPanel loginPanel = new LoginPanel(loginService); RootPanel.get("slot1").add(loginPanel); } }

Now, LoginPanel will get a reference to the servlet that it can call:

public class LoginPanel extends Grid { private LoginServiceAsync loginService; private Label usernameLabel; private TextBox username; private Label passwordLabel; private PasswordTextBox password; private Button login; private Label status; public LoginPanel(LoginServiceAsync loginService) { super(4, 2); this.loginService = loginService; usernameLabel = new Label("Username"); username = new TextBox(); passwordLabel = new Label("Password"); password = new PasswordTextBox(); login = new Button(); login.setText("Login"); login.addClickListener(new ClickListener() { public void onClick(Widget sender) { login(username.getText(), password.getText()); } }); status = new Label(); setWidget(0, 0, usernameLabel); setWidget(0, 1, username); setWidget(1, 0, passwordLabel); setWidget(1, 1, password); setWidget(2, 1, login); setWidget(3, 1, status); } protected void login(String username, String password) { status.setText("Logging in..."); loginService.login(username, password, new AsyncCallback() { public void onSuccess(Object result) { UserDTO user = (UserDTO) result; if(user != null) status.setText("Login ok"); else status.setText("Login failed"); } public void onFailure(Throwable e) { status.setText("Failure: " + e.getMessage()); } }); } }

Next: UI Behavior

DB Importer

HiberObjects

Download

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Implement GWT Client

Remote Procedure Call