Multiple Pages Tutorial in Google Web Toolkit (GWT)

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Multiple Pages Tutorial in Google Web Toolkit (GWT)

I just started learning the Google Web Toolkit (GWT). How to make different HTML pages in my GWT application?

For example, I want to create an application for a bookstore. In this application I will have three pages:

Home pages on which I will welcome the user and offer the user's books.
Page to browse books by category and view details (use GWT widgets)
Check out books online.

Of course, there may be other pages, such as user details, add a new book, etc. So what is the best way to create different pages in GWT and how can I make page-to-page navigation? Are there any examples or tutorials? Or do I even need to create different pages when I can create an entire application on one page?

+60

gwt navigation

Maksim Jun 30 '09 at 4:20

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8 answers

I would use the HyperLink and History class. The good thing about the Hyperlink class is that it sets this token (like # foobar), and all you have to do is to capture an event that fires when the token value changes (ValueChangeEvent). In the case of Handler, you then replace the pages.

Example: welcome address Page: www.yourpage.com/#home on this page there will be a link to the browse book page, when the link is clicked, the new address will be something like this: www.yourpage.com/#browse

And here is the code:

 public class MainEntryPoint implements EntryPoint, ValueChangeHandler { VerticalPanel panel = new VerticalPanel(); Label label=new Label(); public void onModuleLoad() { Hyperlink link1 = new Hyperlink("books", "browse"); Hyperlink link2 = new Hyperlink("user details", "details"); panel.add(link1); panel.add(link2); panel.add(label); RootPanel.get().add(panel); History.addValueChangeHandler(this); //when there is no token, the "home" token is set else changePage() is called. //this is useful if a user has bookmarked a site other than the homepage. if(History.getToken().isEmpty()){ History.newItem("home"); } else { changePage(History.getToken()); } }

 public void onValueChange(ValueChangeEvent event) { changePage(History.getToken()); } public void changePage(String token) { if(History.getToken().equals("browse")) { label.setText("Here would be some books"); } else if (History.getToken().equals("details")) { label.setText("Here would be the user details"); } else { label.setText("Welcome page"); } }

}

code>

+20

Chris Boesing Jun 30 '09 at 12:56

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Awesome! I combined Chris R. with Chris Bosing to come up with this:

This is the start page of the index.

 public class Index implements EntryPoint, ValueChangeHandler<String> { public void onModuleLoad() { History.addValueChangeHandler(this); if (History.getToken().isEmpty()) History.newItem("index"); Composite c = new Login(); FlowControl.go(c); } public void onValueChange(ValueChangeEvent<String> e) { FlowControl.go(History.getToken()); } }

This is a controller or ContentContainer according to Chris R.

 public class FlowControl { private static FlowControl instance; private FlowControl() {} public static void go(Composite c) { if (instance == null) instance = new FlowControl(); // not sure why we need this yet since everything is static. RootPanel.get("application").clear(); RootPanel.get("application").getElement().getStyle().setPosition(Position.RELATIVE); // not sure why, but GWT throws an exception without this. Adding to CSS doesn't work. // add, determine height/width, center, then move. height/width are unknown until added to document. Catch-22! RootPanel.get("application").add(c); int left = Window.getClientWidth() / 2 - c.getOffsetWidth() / 2; // find center int top = Window.getClientHeight() / 2 - c.getOffsetHeight() / 2; RootPanel.get("application").setWidgetPosition(c, left, top); History.newItem(c.getTitle()); // TODO: need to change and implement (or override) this method on each screen } public static void go(String token) { if (token == null) go(new Login()); if (token.equals("cart")) go(new Cart()); if (token.equals("login")) go(new Login()); // Can probably make these constants in this class }

You can then transfer hyperlinks and buttons anywhere in your code. (I have not tried hyperlinks yet.)

  Button submit = new Button("Submit"); submit.addClickHandler(new ClickHandler() { public void onClick(ClickEvent event) { FlowControl.go(new MyScreen()); } });

I added a div to my HTML

 <!-- This is where the application will reside within. It is controlled by FlowControl class. --> <div id="application"></div>

And now all screens should call initWidget () in the constructor instead of adding to the RootPanel, since now it is a Composite class, for example

  initWidget(myPanel); // all composites must call this in constructor

+9

Chloe S. Nov 22 '11 at 10:16

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If you want it to be FULL AJAXified (like a desktop application), you only need one page. Then just change the body content depending on the link.

There is also a google group for GWT, which is very active, and I know that this was asked before, you just need to use the search function.

+5

putolaruan Jun 30 '09 at 5:56

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GWT Multipage is a simple structure for multi-page GWT applications.

+1

Helpa Oct 26 '10 at 23:00

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You can use MVP patern. Here is a small simple library https://code.google.com/p/gwt-simple-mvp/wiki/GettingStarted .

And you can split the code into more js files. https://code.google.com/p/gwt-spliting/

0

Tito100 Jul 08 '13 at 13:20

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I used Chloe S.'s answer (combining Chris R. with Chris Boesing's) to create this application controller for a working GWT web application. The production version is tested (and% 100 works), but this edited version below must be modified to integrate with your own application (start by renaming the page keys to menu items).

AppController.java :

 /** * This App Controller utilizes two static inner-classes (Pages and External) * to manage and server multiple pages with multiple sub-page (through their presenters) * via String key constants which also serve as the literal text for the menu items. * * Pages are added as menu commands in their respective views: * // Add menu items to the menu with commands: * menuItems.put(Pages.PAGE1, mainMenu.addItem(Pages.PAGE1, new Command() { * public void execute() { * History.newItem(Pages.PAGE1); * } * })); * * Pages are fired as History tokens (from entry point java class): * * ** * * Receives history events and pushes them to the AppController using a deferred command. * * Changes the cursor to show waiting. * * @param the value change token * * * public void onValueChange(ValueChangeEvent<String> e) { * // check token to cover first historical "back" navigation: * if(!History.getToken().isEmpty()) { * AppController.waitCursor.execute(); // cursor is reset in page attach method * } * Scheduler.get().scheduleDeferred(new ScheduledCommand() { * public void execute() { * AppController.go(History.getToken()); * } * }); * } * * Wait cursors are implemented as CSS: * * body.wait, body.wait * { * cursor: wait !important; * } * * NOTE: This page swapping implementation technique (based on the StackOverflow solution * found here: [http://stackoverflow.com/questions/1061705/multiple-pages-tutorial-in-google-web-toolkit-gwt][1]) * differs from the obtuse and ancient 2010 GWT framework documentation in that the App Controller manages / handles * adding the widget to the container, and therefore all the Presenters must implement the * "AppControlPresenter" or "AppControlContainerPresenter" interface to give it access to their containers. * (thus eliminating "public void go(final HasWidgets container);" method in all presenter architecture except for 'MainAppPresenter') * There is also no event bus; static method calls are used for any needed interactivity. * * Includes a popup for pages still under construction. */ package com.; import com.google.gwt.core.client.GWT; import com.google.gwt.core.client.Scheduler; import com.google.gwt.core.client.Scheduler.ScheduledCommand; import java.util.HashMap; import java.util.Map; import com.google.gwt.dom.client.Style.Unit; import com.google.gwt.event.logical.shared.AttachEvent; import com.google.gwt.event.logical.shared.ResizeEvent; import com.google.gwt.event.shared.HandlerManager; import com.google.gwt.user.client.History; import com.google.gwt.user.client.Window; import com.google.gwt.user.client.rpc.AsyncCallback; import com.google.gwt.user.client.ui.Composite; import com.google.gwt.user.client.ui.DecoratedPopupPanel; import com.google.gwt.user.client.ui.Frame; import com.google.gwt.user.client.ui.HTML; import com.google.gwt.user.client.ui.Image; import com.google.gwt.user.client.ui.LayoutPanel; import com.google.gwt.user.client.ui.RootLayoutPanel; import com.google.gwt.user.client.ui.RootPanel; import com.google.gwt.user.client.ui.UIObject; /** * */ public class AppController { /** */ public final static String DEFAULT_INITIAL_PAGE1_SUB_PAGE = Pages.PAGE_1A; /** Singleton instance for the AppController */ private static AppController instance = new AppController(); /** Presenter for the main app */ private static MainAppPresenter mainAppPresenter; /** container for the different views */ private static LayoutPanel container; /** sub-container for the different sub-views */ private static LayoutPanel page1Container; /** */ private static DecoratedPopupPanel popup; /** constant for Style-Dependent names for menu items (see menu-style.css) */ public final static String MENU_ACTIVE_STYLE = "active"; /** constant for Style-Dependent class name in css */ public final static String CURSOR_WAIT_CLASS = "wait"; /** */ public final static String POPUP_DEMO_ID = "popupDemo"; /** */ public final static int DEMOP_POPUP_VERTICAL_OFFSET = 0; /** */ public final static String POPUP_DEMO_STATEMENT = "<span class='text'>This page is under construction</span>" + "<span class='char'>&hellip;</span>"; /** */ public static ScheduledCommand waitCursor = new ScheduledCommand() { @Override public void execute() { AppController.waitCursor(true); } }; /** */ public static ScheduledCommand normalCursor = new ScheduledCommand() { @Override public void execute() { AppController.waitCursor(false); } }; /** Flag for determining if the page was reloaded */ private static boolean reloaded = false; private static final LoginServiceAsync loginRpcService = GWT.create(LoginService.class); /** * Called on the resize event to set the position of the demo popup * window to be adjusted to the correct dimensions (size and positoin) * regardless of screen size. */ private static ScheduledCommand resetPopupDimensions = new ScheduledCommand() { @Override public void execute() { if(!UNDER_CONSTRUCTION || popup == null) { return; } int demoWidth = Math.round(Window.getClientWidth() / MainApp.PHI), demoYPosition = Window.getClientHeight() / 2 - Math.round(popup.getOffsetHeight() / 2); popup.setWidth(String.valueOf(demoWidth) + "px"); if(popup.getOffsetWidth() >= Window.getClientWidth()) { popup.setWidth("100%"); popup.setPopupPosition(0, demoYPosition); } else { popup.setPopupPosition(Window.getClientWidth() / 2 - (popup.getOffsetWidth() / 2), demoYPosition); } } }; /** */ private static final String LOGIN_OBJECT_NAME = "Login Presenter Object"; /** * static inner-class for external websites */ public static class External { /** The frame to contain the website */ private static Frame frame; /** */ public static final String EXTERNAL_URL_1 = "http://"; /** */ public static final String EXTERNAL_URL_2 = "http://"; /** * @returns true if the name of the token is equal to one of the URLs * @param token the name to check */ public static boolean has(String token) { return token.equalsIgnoreCase(EXTERNAL_URL_1) || token.equalsIgnoreCase(EXTERNAL_URL_2); } /** * Gets the external Frame object * @param url * @return Frame */ public static Frame get(String url) { if(frame == null) { frame = new Frame(url); frame.addAttachHandler(new AttachEvent.Handler() { @Override public void onAttachOrDetach(AttachEvent event) { // hide the popup: showPopup(false); Scheduler.get().scheduleFinally(resetPopupDimensions); Scheduler.get().scheduleFinally(normalCursor); } }); } else if(!frame.getUrl().equalsIgnoreCase(url)) { frame.setUrl(url); } return frame; } } /** * static inner-class for holding pages activated by the app main menu commands */ public static class Pages { /** */ public static final String PAGE1 = "foo"; /** */ public static final String PAGE2 = "bar"; /** */ public static final String PAGE_1A = "baz"; /** */ public static final String PAGE_1B = "qux"; /** */ public static String lastPage; /** */ public static String lastPage1SubPage; /** */ public static String unsavedMessage; /** */ private static HashMap<String, AppControlPresenter> pageMap; /** */ private static AppControlPresenter presenter; /** */ private static Composite view; /** * initializes the hashmap of pages */ public static void init() { pageMap = new HashMap<String, AppControlPresenter>(); } /** * @returns true if the name of the token is equal to one of the pages * @param token the name to check */ public static boolean has(String token) { return token.equalsIgnoreCase(PAGE1) || token.equalsIgnoreCase(PAGE2) || token.equalsIgnoreCase(PAGE_1A); } /** * Gets the correct page container to display as a Composite * @param page the token name of the page * @return Composite page */ public static Composite get(String page) { view = null; presenter = null; if(page.equalsIgnoreCase(PAGE1)) { if(pageMap.get(PAGE1) == null) { pageMap.put(PAGE1, new Page1Presenter(PAGE1)); page1Container = ((AppControlContainerPresenter) pageMap.get(PAGE1)).getContentPane(); } presenter = pageMap.get(PAGE1); lastPage = page; mainAppPresenter.setCurrentMenuItem(page); } else if(page.equalsIgnoreCase(PAGE_1A) || page.equalsIgnoreCase(PAGE_1B) { if(pageMap.get(PAGE1) == null) { pageMap.put(PAGE1, new Page1Presenter(PAGE1)); page1Container = ((AppControlContainerPresenter) pageMap.get(PAGE1)).getContentPane(); } presenter = pageMap.get(PAGE1); lastPage1SubPage = page; view = ((AppControlContainerPresenter)presenter).setCurrentPage(page); } else if(page.equalsIgnoreCase(PAGE2)) { if(pageMap.get(PAGE2) == null) { pageMap.put(PAGE2, new Page2Presenter(PAGE2)); } presenter = pageMap.get(PAGE2); lastPage = PAGE2; mainAppPresenter.setCurrentMenuItem(page); } else if(External.has(page)) { throw new Error("App Controller Error -- Use 'External' inner-class for: " + page); } else { throw new Error("App Controller Error -- Page name not found: " + page); } if(view == null) { view = (Composite)presenter.view(); } view.addAttachHandler(new AttachEvent.Handler() { @Override public void onAttachOrDetach(AttachEvent event) { AppController.showPopup(false); presenter.updateAttachOrDetach(event); Scheduler.get().scheduleFinally(resetPopupDimensions); Scheduler.get().scheduleFinally(normalCursor); } }); return view; } /** * Gets the current AppControlPresenter for the last page. * @returns the current AppControlPresenter */ public static AppControlPresenter getCurrentPresenter() { return presenter; } /** * Gets an AppControlPresenter from the pageMap. * @param token the name of the presenter * @returns the AppControlPresenter */ public static AppControlPresenter getPresenter(String token) { return pageMap.get(token); } /** * Returns true if the page is already loaded. * @param token name of the page */ public static boolean alreadyLoaded(String token) { MainApp.debug(1, "[already loaded: " + presenter.toString() + " (token: " + token + ")"); return presenter.toString().equalsIgnoreCase(token); } /** * Returns true if the page is visible * @param page the token name of the page */ public static boolean isVisible(String page) { UIObject component = pageMap.get(page).view(); return !(component.getOffsetHeight() == 0 && component.getOffsetWidth() == 0); } /** * Returns true if the page is visible * @param presenter the AppControlPresenter instance */ public static boolean isVisible(AppControlPresenter presenter) { UIObject component = presenter.view(); return !(component.getOffsetHeight() == 0 && component.getOffsetWidth() == 0); } /** * Returns true if the application has unsaved data. * Iterates through all the pages and checks each presenter. */ public static boolean unsavedData() { if(pageMap.isEmpty()) return false; boolean unsaved = false; for(Map.Entry<String, AppControlPresenter> entry : pageMap.entrySet()) { AppControlPresenter presenter = entry.getValue(); if(presenter != null && presenter.unsavedData()) { MainApp.debug(1, "(!) " + presenter.toString() + " has unsaved data"); unsavedMessage = presenter.dataDescription(); unsaved = true; break; // just need to know one exists for now (window closing event) } } return unsaved; } /** * Called on a resize event on the window. Iterates through all the pages * and tells their presenters to resize their content. */ public static void resize() { for(Map.Entry<String, AppControlPresenter> entry : pageMap.entrySet()) { AppControlPresenter presenter = entry.getValue(); if(presenter != null && isVisible(presenter)) { presenter.resize(); } } } } //end class Pages /** * @returns true if the history token is equal to any of the pages in the app */ public static boolean hasHistory() { String token = History.getToken(); return External.has(token) || Pages.has(token); } /** * Starts the login view at the root layout level */ public static void goLoginScreen() { //check for reload: if(hasHistory()) { MainApp.debug(1, "(!) AppController has History on Login"); reloaded = true; } else { reloaded = false; } RootLayoutPanel.get().clear(); RootLayoutPanel.get().add(new LoginPresenter(LOGIN_OBJECT_NAME).view()); } /** * @returns the last "Page1" page */ public static String getLastPage1Page() { if(Pages.lastPage1SubPage == null || Pages.lastPage1SubPage.isEmpty()) { Pages.lastPage1SubPage = DEFAULT_INITIAL_PAGE1_SUB_PAGE; } return Pages.lastPage1SubPage; } /** * Tells the app to start with the Page1 page. * @param username the username of the person logged-in */ public static void goMainApp(String username) { //hide the login background: RootPanel.getBodyElement().getStyle().setProperty("background", "none"); mainAppPresenter = new MainAppPresenter(username); RootLayoutPanel.get().clear(); mainAppPresenter.go(RootLayoutPanel.get()); //get the center panel: container = mainAppPresenter.getContainer(); //check for reload: //NOTE: the token will be empty if the user refreshes // and navigates all the way back to the zero-state // from the login screen. //NOTE: this logic may change after user-persistence is implemented if(hasHistory() || History.getToken().isEmpty()) { // reset the reloaded flag: reloaded = false; if(History.getToken().isEmpty()) { //land on the first page: History.newItem(AppController.Pages.PAGE1); } else { MainApp.debug(2, "(!) AppController has History on reload: " + History.getToken()); History.fireCurrentHistoryState(); } } else { //land on the first page: History.newItem(AppController.Pages.PAGE1); } } /** * */ public static void checkIfSessionActive() { loginRpcService.loginFromSession(new AsyncCallback<LoginSummary>() { @Override public void onFailure(Throwable throwable) { goLoginScreen(); } @Override public void onSuccess(LoginSummary loginSummary) { if (loginSummary.getErrorString() != null) goLoginScreen(); else goMainApp(loginSummary.getUser().getName()); } }); } /** * */ public static void sessionLogout() { DialogBoxWidget.confirm(200, "Logout", "Are you sure you want to log out?", new ConfirmDialogCallback() { @Override public void onAffirmative() { loginRpcService.logout(new AsyncCallback<Void>() { @Override public void onFailure(Throwable throwable) { goLoginScreen(); } @Override public void onSuccess(Void aVoid) { goLoginScreen(); } }); } @Override public void onCancel() { } }); } /** * Shows or hides the "Under Construction" popup if UNDER_CONSTRUCION is true. * @param show true to show and false to hide */ public static void showPopup(boolean show) { if(MainApp.UNDER_CONSTRUCTION && popup != null) { if(show) { popup.show(); } else { popup.hide(); } } } /** * Called by every history event fired (including the back and forward buttons). * Ignores the login and empty index historically. * @param token the name of the page to load */ public static void go(String token) { if(reloaded) { normalCursor.execute(); } if(token == null || token.isEmpty() || reloaded == true) return; MainApp.debug("<history changed> - AppController.go()-> " + token); // build the popup message for all unfinished pages: if(MainApp.UNDER_CONSTRUCTION) { if(popup == null) { popup = new DecoratedPopupPanel(false); popup.ensureDebugId(POPUP_DEMO_ID); popup.addStyleDependentName(POPUP_DEMO_ID); popup.setWidget(new HTML(new Image("images/workingman.png") + POPUP_DEMO_STATEMENT + new Image("images/workingmanFLIP.png"))); } } // check token for which page to return: if(token.equalsIgnoreCase(External.EXTERNAL_URL_1)) { MainAppPresenter.clearActiveMenuItems(); setExternalContentURL(External.get(token)); } else if(token.equalsIgnoreCase(External.EXTERNAL_URL_2)) { MainAppPresenter.clearActiveMenuItems(); setExternalContentURL(External.get(token)); } else if(token.equalsIgnoreCase(Pages.PAGE1)) { setContent(Pages.get(Pages.PAGE1)); setPage1Content(Pages.get(getLastPage1Page())); } else if(token.equalsIgnoreCase(Pages.PAGE_1A) || token.equalsIgnoreCase(Pages.PAGE_1B)) { setContent(Pages.get(Pages.PAGE1)); setPage1Content(Pages.get(token)); } else if(token.equalsIgnoreCase(Pages.PAGE2)) { setContent(Pages.get(Pages.PAGE2)); } else { // default behavior for a page not described: MainApp.debug(2, "(!) Unknown page: " + token); setContent(Pages.get(token)); } } /** * Called by MainApp on a window resize event. * @param e the ResizeEvent */ public static void resize(ResizeEvent e) { Scheduler.get().scheduleDeferred(new ScheduledCommand() { @Override public void execute() { if(mainAppPresenter != null) { mainAppPresenter.resize(); } Pages.resize(); Scheduler.get().scheduleFinally(resetPopupDimensions); } }); } /** * Changes the cursor to "wait" or "auto" depending on the parameter * @param wait true to set the cursor to waiting */ private static void waitCursor(Boolean wait) { if(wait) { RootPanel.getBodyElement().addClassName(CURSOR_WAIT_CLASS); } else { RootPanel.getBodyElement().removeClassName(CURSOR_WAIT_CLASS); } } /** * Private Constructor which initializes the Pages object. */ private AppController() { Pages.init(); } /** * Sets the content of the main app container to one of the "Pages." * @param c the Composite widget to be added */ private static void setContent(Composite c) { container.clear(); container.add(c.asWidget()); } /** * Sets the content of the main app container an external URL. * @param f the Frame by which external web sites are added */ private static void setExternalContentURL(Frame f) { container.clear(); container.add(f); // must reset the width and height every time: f.getElement().getStyle().setWidth(100, Unit.PCT); f.getElement().getStyle().setHeight(100, Unit.PCT); } /** * Sets the content of the Page1 container to one of the sub pages. * @param c the Composite widget to be added */ private static void setPage1Content(Composite c) { page1Container.clear(); page1Container.add(c.asWidget()); } }

AppControlPresenter.java:

 package com.*; import com.google.gwt.event.logical.shared.AttachEvent; import com.google.gwt.user.client.ui.Composite; /** * Base interface for all 'Presenters' used by AppController.java * NOTE: classes that implement this interface do not launch the presenter view * into the provided container; rather, the view is retrieved and used by the * AppController instance by calling the 'view()' method */ public interface AppControlPresenter { /** * Gets the view (for use in AppController.java) */ public Composite view(); /** * Indicates if current search data is present and unsaved. * @returns true to if a search is still active */ public boolean unsavedData(); /** * Called on resize event to notify presenters with visible * components that need resizing for different screen sizes. * @returns true if elements were resized */ public boolean resize(); /** * Called on attachEvents to tell the presenter to update. * @param event the AttachEvent */ public void updateAttachOrDetach(AttachEvent event); /** * Gets the message to display for unsaved data. * @returns a message String describing the data */ public String dataDescription(); /** * Gets a fully qualified name for use in comparisons * @return the name of this presenter used by the <code>AppController</code> */ public String toString(); }

AppControlContainerPresenter.java:

 package com.*; import com.google.gwt.user.client.ui.Composite; import com.google.gwt.user.client.ui.LayoutPanel; /** */ public interface AppControlContainerPresenter extends AppControlPresenter { /** * * @return */ public LayoutPanel getContentPane(); /** * * @param pageName * @return */ public Composite setCurrentPage(String pageName); }

0

PAINKILLER 13 . '14 21:29

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, GWT. .

-2

Luis Mesa 06 . '10 22:58

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Chris Ruffalo · Accepted Answer · 2009-06-30 14:04

What I usually do in such situations is to first develop a web page structure. I will have a div for the title, sidebar and footer. I will also have a div in my HTML for the main content.

Example:

 <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta name='gwt:module' content='org.project.package.Core=org.project.package.Core'> </head> <body> <!-- Load the JavaScript code for GWT --> <script language="javascript" src="ui/org.project.package.ui.Core.nocache.js"></script> <!-- For some unknown reason in Internet Explorer you have to have cellpadding/spacing ON THE ELEMENT and not on the STYLE if it is in the body tag like this --> <table id="wrapper" cellpadding="0" cellspacing="0" style="width: 100%;height: 100%;"> <!-- Header row --> <tr style="height: 25%;"> <td colspan="2" id="header"></td> </tr> <!-- Body row and left nav row --> <tr style="height: 65%;"> <td id="leftnav"></td> <td id="content"></td> </tr> <!-- Footer row --> <tr style="height: 10%;"> <td colspan="2" id="footer"></td> </tr> </table> <!-- This iframe handles history --> <iframe id="__gwt_historyFrame" style="width:0;height:0;border:0"></iframe> </body> </html>

(If you like based layouts

Then you create your entry point (in my case Core.java ), as usual, setting each of the elements as needed.

 RootPanel.get("header").add(new Header()); RootPanel.get("leftnav").add(new NavigationMenu()); RootPanel.get("footer").add(new Footer());

Of course, it is possible to have a static footer and header, but this is neither here nor there.

I also have an abstract class called "Content". Content objects extend Composite and will have various methods to simplify the creation and layout of a new page. Every page that I create for this application, whether it’s a help screen, a search screen, a shopping cart or something else, is of type Content .

Now I am creating a class called ContentContainer. This is a singleton that is responsible for managing the "content" element. It has one method called "setContent" that accepts objects of type "Content". Then it basically removes something inside the "content" <td> and replaces it with any Composite widgets that you assign using the setContent method. The setContent method also handles header and header control. Basically, the ContentContainer serves to aggregate all the various anchor points that you may need if each page content needs to “know” about all the functions that it needs to perform.

Finally, you need a way to get to this page, right? It's simple:

 ContentContainer.getInstance().setContent(new Search());

Put the above event in a random press and you will be golden.

The only things your other widgets need to be related is the ContentContainer and the type of content they add.

The disadvantages that I see in the ChrisBo approach are that you have a list that should be maintained in tokens → pages. Another drawback that I see is that I do not see how you can have a real story system with this method.

One thing he suggests in my approach is that all page options are pretty centralized. I would use some kind of Enum, or at least a static class with String values, to prevent me from confusing the links.

In any case, I think that this paragraph can be summarized as follows: replace the contents of some element of the central page based ~~on the fact that your user clicks the~~ actions performed by your user (s).

Multiple Pages Tutorial in Google Web Toolkit (GWT)

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