CODEWITHSUNDEEP
javajavascriptajaxgwt
Michael Bradey
Michael Bradey

Reputation: 21

Getting Started With GWT

I have been looking into the GWT for a couple of days now and I have some confusion.

I come from a PHP/JSP background so when I wanted to create a website that had multiple pages I would just create a PHP page for each page and then let the user select what to view.

Now that I am looking into GWT I don't really understand how this is done?

Lets say I would like my site to have three pages (index.html, help.html, contact.html), when a GWT app is loaded the onModuleLoad() method is called. How would I then code each separate pages widgets then using only this one method?

Looking at the example GWT application that is created in Eclipse, A single HTML page is created. How would I create an application with multiple pages if there is only a single onModuleLoad() method?

Upvotes: 2

Views: 736

Answers (3)

torbinsky
torbinsky

Reputation: 1468

GWT can be used in a Web 2.0, client-side application way as mentioned by Chris Lercher and nvcleemp or you can use it in conjunction with a more traditional page view/reload model. If you simply want to inject DHTML functionality into existing, static pages, you can look for specific element id's for injecting into or you could read a javascript embedded configuration variable when onModuleLoad() is called to determine what state/mode you are in and what type of GWT client functionality you should be running.

For example, using the different injection points:

page 1:

<html>
<head>
...
<script type="text/javascript" src="yourmodule.nocache.js"></script>
...
</head>
<body>
...
<div id="injectMode1"></div>
...
</body>
</html>

page 2:

<html>
<head>
...
<script type="text/javascript" src="yourmodule.nocache.js"></script>
...
</head>
<body>
...
<div id="injectMode2"></div>
...
</body>
</html>

Your GWT EntryPoint:

@Override
public void onModuleLoad() {
    final Panel mode1 = RootPanel.get("injectionMode1");
    if (mode1 != null) {
        mode1.add(new ModeOneWidget());
    }
    final Panel mode2 = RootPanel.get("injectionMode2");
    if (mode2 != null) {
       mode2.add(new ModeTwoWidget());
    }
}

EDIT:

Using javascript variables, on each page that you want to embed GWT functionality you can do something similar to:

page foo:

<html>
<head>
...
<script type='text/javascript'> 
    var appMode="mode1";
</script>
<script type="text/javascript" src="yourmodule.nocache.js"></script>
...
</head>
...

Your GWT EntryPoint:

private static final native String getAppMode()/*-{
    return $wnd.appMode;
}-*/;

@Override
public void onModuleLoad() {
    String appMode = getAppMode();
    if(appMode != null){
        if(appMode.equals(MODE1)){
        ...
        }
        ...
    }
}

Upvotes: 2

nvcleemp
nvcleemp

Reputation: 560

GWT is used to build applications like e.g. Google Reader or Gmail: this means that there is just 'one' page. You could have a 'window' inside that page that shows the contact information and a 'window' that shows the help information. When the users clicks the corresponding link you show that 'window'

Upvotes: 0

Chris Lercher
Chris Lercher

Reputation: 37788

GWT uses JavaScript to modify the page content. So you don't load a new page [*].

With GWT, you don't need the server to create dynamic HTML content anymore. It's created dynamically on the client side (using static JavaScript code). When you need to load something from the server, you just load data objects (in JSON or XML format, or using GWT-RPC). The client may then use this data to build HTML snippets (to set innerHTML) or DOM objects to modify the browser's DOM tree.

With GWT, you don't have to build these snippets manually: You can use Widgets and UiBinder (client side HTML templating, enhanced with GWT tags and dynamic parameters).

[*] There are some special cases (e.g. if you have a https login page, whereas the rest of the app might use http), where you do load a new page, but that means either that your other page doesn't use GWT at all, or that you create a separate GWT module for it. Of course you can share some of the Java classes between these modules.

Upvotes: 0

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