Common class libraries and function introduction in GWT user framework
GWT (Google Web Toolkit) is a Java framework for building a rich Internet application (RIA).It allows developers to use Java to develop front -end applications and compile them into high -efficiency JavaScript code.GWT provides many common libraries and functions, enabling developers to build powerful and interactive network applications.Here are some common GWT libraries and functions, and Java code examples.
1. GWT user interface (GWT-UI): GWT provides a class library for building a user interface.Developers can use various Panel, Widget and Layout and other components provided by GWT, as well as event processing mechanisms to build a rich and interactive front -end interface.
Example code:
Button button = new Button("Click me");
button.addClickHandler(event -> {
// Process button click event
});
RootPanel.get().add(button);
2. Remote process call (RPC): GWT's RPC function allows remote method calls between clients and servers.Developers can use GWT's RPC mechanism to define the interface between clients and server, and call the server method in the client code.
Example code:
Define service interface:
public interface MyService extends RemoteService {
void doSomething(String param);
}
Implement service interface:
public class MyServiceImpl extends RemoteServiceServlet implements MyService {
public void doSomething(String param) {
// Treatment of business logic
}
}
Call on the client:
MyServiceAsync myService = GWT.create(MyService.class);
myService.doSomething("Hello GWT", new AsyncCallback<Void>() {
public void onSuccess(Void result) {
// Processing successful callback
}
public void onFailure(Throwable caught) {
// Processing failure recovery
}
});
3. Component communication and event processing: GWT provides a set of event processing mechanisms for communication and message transmission between components.Developers can use the GWT event processor to define and register events, and to trigger and handle events accordingly when needed.
Example code:
Definition and trigger events:
public class MyEvent extends GwtEvent<MyEventHandler> {
public static final Type<MyEventHandler> TYPE = new Type<>();
public Type<MyEventHandler> getAssociatedType() {
return TYPE;
}
protected void dispatch(MyEventHandler handler) {
handler.onMyEvent(this);
}
}
// trigger event
eventBus.fireEvent(new MyEvent());
Processing event:
public interface MyEventHandler extends EventHandler {
void onMyEvent(MyEvent event);
}
// Register event processor
eventBus.addHandler(MyEvent.TYPE, event -> {
// Treatment event
});
4. Internationalization (i18N) support: GWT provides international support, which can easily localize the application into multiple languages.Developers can use GWT's international and resource packages to use the text content and user interface of international applications.
Example code:
Define resource packs:
public interface MyResources extends ClientBundle {
@Source("MyLocalizedText.properties")
MyLocalizedText localizedText();
}
public interface MyLocalizedText extends Constants {
@Key("helloMessage")
String helloMessage();
}
Use localized resources:
MyResources resources = GWT.create(MyResources.class);
String message = resources.localizedText (). Hellom "; // Get localized text based on the current language
The above is the introduction of some common libraries and functions in the GWT user framework, showing the powerful functions and flexibility of GWT in the development of front -end application.Developers can use these functions to build high -quality and scalability Internet applications.
