In this session, see Google Web Toolkit used in exotic and creative ways to solve interesting engineering problems, from authoring OpenSocial apps that run as both Web gadgets and native Android applications, to developing Adobe AIR applications using GWT, compiling CSS selectors to Javascript at compile time, running multithreaded code with GWT and Gears workers, or exporting GWT libraries for JavaScript users. Learn the secrets of writing "faster than possible" GWT code, how to use Generators and Linkers in harmony, and make seamless procedure calls from GWT code to other environments like Flash, Gears, or Android.
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GWT Extreme!
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3. BUDD: Why did he call it GWT Extreme? BILL: I guess he thought it sounded kinda cool.
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12. GwtQuery Example Compile Time Parsing: Bottom Line ul > li:first-child becomes document.evaluate(“ul/li[position() = 1]”)
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15. Demo: Progressively Enhancing <UL> into PowerPoint-like slide transitions Sample Code < div class =" slide transition-fade"> Slide 1 < ul class="transition-fade"> < li > Point One </li> < li > Point Two </li> < li > Point Three </li> </ul> </div> < div class =" slide transition-fade"> Slide 2 < ul class="transition-appear"> < li > Slide 2 Point One </li> < li > Slide 2 Point Two </li> < li > Slide 3 Point Three </li> </ul> </div>
16. GwtQuery code Sample Code for Selectors needed interface Slide extends Selectors { // find all LI elements rooted at ctx @Selector ( "li" ) NodeList<Element> slideBulletsCtx ( Node ctx ); // Find all DIV elements with class 'slide' @Selector ( "div.slide" ) NodeList<Element> allSlides (); }
18. Sample of Generated Output for Selector “.slide li” W3C Selector API version public class SlideNativeImpl extends SelectorEngine implements MySelectors { public final NodeList<Element> slideBullets() { return querySelectorAll ( ".slide li" ); } }
19. Sample of Generated Output for Selector “.slide li” XPath Version public class SlideXPathImpl extends SelectorEngine implements Slide { public final NodeList<Element> slideBullets() { return xpathEvaluate ( "./descendant::*[contains(concat(' ', @class, ' '), ' slide ')]/descendant::li" ); } }
29. Example: Syndroid Gadgets can span many Platforms Android iGoogle OSX Google Desktop Yahoo And many Flash widget startups
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31. Example: Android Native Interface What if Android browser had a window.locationService object? public class LocationServiceClient implements LocationService { public native String getLocation() /*-{ return $wnd. locationService . getLocation() ; }-*/; }
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33. Android Native Interface AndroidNativeInterface LocationService String getLocation(); extends LocationServiceClient String getLocation() { return $wnd.locationService.getLocation(); } implements Emitted by Generator LocationServiceImpl String getLocation() { return ...android native code... } impl Written by Developer Android Bootstrap Bind LocationServiceImpl to window.locationService Provided by Linker
36. Example: Android Native Interface To use LocationService service = GWT.create ( LocationService.class ); Window.alert(“Your location is: “+ service.getLocation() );
37. Example: Linker Generated BootstrapActivity LocationServiceImpl gets exposed as window.locationService public class BootstrapActivity extends Activity { @Override public void onCreate(Bundle icicle) { super.onCreate(icicle); setContentView(getBootstrapView()); } public WebView getBootstrapView() { WebView wv=new WebView(this); wv.getSettings().setJavaScriptEnabled(true); wv.getSettings().setUseDesktopUserAgent(true); wv.getSettings().setLoadsImagesAutomatically(true); wv.addJavascriptInterface(new ContactsServiceImpl(this), "contactsService"); wv.addJavascriptInterface(new LocationServiceImpl (this), "locationService" ); wv.loadUrl("file:///android_asset/index.html"); return wv; } } @ImplementedBy @ANIBinding
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