google gin
DESCRIPTION
A basic tutorial shows you how to use Google GIN.GIN (GWT INjection) is Guice for Google Web Toolkit client-side codeTRANSCRIPT
What the heck is Google GIN?
• GIN = GWT INjection
• Guice brings automatic dependency injection to server side code, while GIN is for client-side code.
• GIN is built on top of Guice and uses (a subset of) Guice's binding language
What the heck is Google GIN?
• GIN = GWT INjection
• Guice brings automatic dependency injection to server side code, while GIN is for client-side code.
• GIN is built on top of Guice and uses (a subset of) Guice's binding language
GWT client-side code
GIN
What the heck is Google GIN?
• GIN = GWT INjection
• Guice brings automatic dependency injection to server side code, while GIN is for client-side code.
• GIN is built on top of Guice and uses (a subset of) Guice's binding language
GWT client-side code
GWT server-side code
GIN Guice
How to use GIN ?
This tutorial shows you
5 Steps to remember
1. Design the application with Interfaces IA,IB,…
5 Steps to remember
1. Design the application with Interfaces IA,IB,…
2. Create concrete classes AImpl, BImpl,… to implement interfaces IA,IB,… Remember: use @Inject to mark the non-default constructor.
5 Steps to remember
1. Design the application with Interfaces IA,IB,…
2. Create concrete classes AImpl, BImpl,… to implement interfaces IA,IB,… Remember: use @Inject to mark the non-default constructor.
3. Create AppClientModule to configure which implementation is bound to which interface
5 Steps to remember
1. Design the application with Interfaces IA,IB,…
2. Create concrete classes AImpl, BImpl,… to implement interfaces IA,IB,… Remember: use @Inject to mark the non-default constructor.
3. Create AppClientModule to configure which implementation is bound to which interface
4. Create interface AppGinjector with the AppClientModule in the annotation @GinModules.
@GinModules({AppClientModule.class, other modules …})
5 Steps to remember
1. Design the application with Interfaces IA,IB,…
2. Create concrete classes AImpl, BImpl,… to implement interfaces IA,IB,… Remember: use @Inject to mark the non-default constructor.
3. Create AppClientModule to configure which implementation is bound to which interface
4. Create interface AppGinjector with the AppClientModule in the annotation @GinModules.
5. Generate code for AppGinjector and use it
AppPresenter aPres = injector.getAppPresenter();
aPres.bind();
RootPanel.get().add(aPres.getDisplay().asWidget());
private final AppGinjector injector = GWT.create(AppGinjector.class);
@GinModules({AppClientModule.class, other modules …})
Step 1: Design an Interface
public class ConfigPresenter extends WidgetPresenter<ConfigPresenter.Display>{
public interface Display extends NameAwareWidgetDisplay, WidgetDisplay {
public HasClickHandlers getSaveClick();
public void updateConfig(Config config);
}
…
}
Step 1: Design an Interface
public class ConfigPresenter extends WidgetPresenter<ConfigPresenter.Display>{
public interface Display extends NameAwareWidgetDisplay, WidgetDisplay {
public HasClickHandlers getSaveClick();
public void updateConfig(Config config);
}
…
}
For gwt-dispatch developers: Normally, we create a Display interface as an inner interface of a Presenter class
Step 2: Implement the interface
public class ConfigView extends Composite implements ConfigPresenter.Display {
private VerticalPanel panel = new VerticalPanel();
private AppConstants constants;
@Inject
public ConfigView(AppConstants constants, AppMessages messages) {
this.constants = constants;
panel.addStyleName(AppCSS.C_config_container);
panel.add(new HTML("<h1>Config view: comming soon<h1>"));
initWidget(panel);
}
…
}
Step 2: Implement the interface
public class ConfigView extends Composite implements ConfigPresenter.Display {
private VerticalPanel panel = new VerticalPanel();
private AppConstants constants;
@Inject
public ConfigView(AppConstants constants, AppMessages messages) {
this.constants = constants;
panel.addStyleName(AppCSS.C_config_container);
panel.add(new HTML("<h1>Config view: comming soon<h1>"));
initWidget(panel);
}
…
}
If the class has no default constructor, then a @Inject annotation is required. Otherwise, you will get a RuntimeException (“No @Inject or default constructor found for class …. ”)
Step 3: Create class AppClientModule
public class AppClientModule extends AbstractPresenterModule {
@Override
protected void configure() {
bind(EventBus.class).to(DefaultEventBus.class).in(Singleton.class);
bind(PlaceManager.class).to(AppPlaceManager.class);
bindPresenter(LoginPresenter.class, LoginPresenter.Display.class, LoginView.class);
bindPresenter(MainPresenter.class, MainPresenter.Display.class, MainView.class);
bindPresenter(AppPresenter.class, AppPresenter.Display.class, AppView.class);
bind(LoginPresenterPlace.class).in(Singleton.class);
bind(ContactsPresenterPlace.class).in(Singleton.class);
…
bind(LoginPresenter.class).in(Singleton.class);
bind(LoginPresenter.Display.class).to(LoginView.class);
}
}
Step 3: Create class AppClientModule
public class AppClientModule extends AbstractPresenterModule {
@Override
protected void configure() {
bind(EventBus.class).to(DefaultEventBus.class).in(Singleton.class);
bind(PlaceManager.class).to(AppPlaceManager.class);
bindPresenter(LoginPresenter.class, LoginPresenter.Display.class, LoginView.class);
bindPresenter(MainPresenter.class, MainPresenter.Display.class, MainView.class);
bindPresenter(AppPresenter.class, AppPresenter.Display.class, AppView.class);
bind(LoginPresenterPlace.class).in(Singleton.class);
bind(ContactsPresenterPlace.class).in(Singleton.class);
…
bind(LoginPresenter.class).in(Singleton.class);
bind(LoginPresenter.Display.class).to(LoginView.class);
}
} Don’t need to bind LoginPresenter and LoginPresenter.Display Because they are already “bind” above in the bindPresenter(…)
See the implementation of the bindPresenter() in the next slide …
Note: Implementation of bindPresenter()
public abstract class AbstractPresenterModule extends AbstractGinModule {
protected <D extends Display> void bindPresenter( Class<? extends Presenter> presenter,
Class<D> display, Class<? extends D> displayImpl )
{
bind( presenter ).in( Singleton.class );
bindDisplay( display, displayImpl );
}
protected <D extends Display> void bindDisplay( Class<D> display, Class<? extends D>
displayImpl )
{
bind( display ).to( displayImpl );
}
…
}
Note: Implementation of bindPresenter()
public abstract class AbstractPresenterModule extends AbstractGinModule {
protected <D extends Display> void bindPresenter( Class<? extends Presenter> presenter,
Class<D> display, Class<? extends D> displayImpl )
{
bind( presenter ).in( Singleton.class );
bindDisplay( display, displayImpl );
}
protected <D extends Display> void bindDisplay( Class<D> display, Class<? extends D>
displayImpl )
{
bind( display ).to( displayImpl );
}
…
}
DisplayImpl class is bound to Display interface
Note: Implementation of bindPresenter()
public abstract class AbstractPresenterModule extends AbstractGinModule {
protected <D extends Display> void bindPresenter( Class<? extends Presenter> presenter,
Class<D> display, Class<? extends D> displayImpl )
{
bind( presenter ).in( Singleton.class );
bindDisplay( display, displayImpl );
}
protected <D extends Display> void bindDisplay( Class<D> display, Class<? extends D>
displayImpl )
{
bind( display ).to( displayImpl );
}
…
}
Presenter is bound as Singleton. It means there is no new instance created when you invoke AppGinjector.getPresenter()
DisplayImpl class is bound to Display interface
Step 4: Define AppGinjector interface
@GinModules({ClientDispatchModule.class,AppClientModule.class})
public interface AppGinjector extends Ginjector {
public AppPresenter getAppPresenter();
public PlaceManager getPlaceManager();
public EventBus getEventBus();
}
Step 4: Define AppGinjector interface
@GinModules({ClientDispatchModule.class,AppClientModule.class})
public interface AppGinjector extends Ginjector {
public AppPresenter getAppPresenter();
public PlaceManager getPlaceManager();
public EventBus getEventBus();
}
List of modules. Each module class contains only one configure() method to specify which implementation is bound to which interface.
Step 4: Define AppGinjector interface
@GinModules({ClientDispatchModule.class,AppClientModule.class})
public interface AppGinjector extends Ginjector {
public AppPresenter getAppPresenter();
public PlaceManager getPlaceManager();
public EventBus getEventBus();
}
List of modules. Each module class contains only one configure() method to specify which implementation is bound to which interface.
A helper module provided by gwt-dispatch (just ignore it for now)
Step 4: Define AppGinjector interface
@GinModules({ClientDispatchModule.class,AppClientModule.class})
public interface AppGinjector extends Ginjector {
public AppPresenter getAppPresenter();
public PlaceManager getPlaceManager();
public EventBus getEventBus();
}
List of modules. Each module class contains only one configure() method to specify which implementation is bound to which interface.
A helper module provided by gwt-dispatch (just ignore it for now)
You create it in step 3!
Step 4: Define AppGinjector interface
@GinModules({ClientDispatchModule.class,AppClientModule.class})
public interface AppGinjector extends Ginjector {
public AppPresenter getAppPresenter();
public PlaceManager getPlaceManager();
public EventBus getEventBus();
}
Use whatever name you want!
List of modules. Each module class contains only one configure() method to specify which implementation is bound to which interface.
A helper module provided by gwt-dispatch (just ignore it for now)
You create it in step 3!
Step 4: Define AppGinjector interface
@GinModules({ClientDispatchModule.class,AppClientModule.class})
public interface AppGinjector extends Ginjector {
public AppPresenter getAppPresenter();
public PlaceManager getPlaceManager();
public EventBus getEventBus();
}
Return type is important. Injector will return the instance basing on type.
Use whatever name you want!
List of modules. Each module class contains only one configure() method to specify which implementation is bound to which interface.
A helper module provided by gwt-dispatch (just ignore it for now)
You create it in step 3!
Step 5: Using Injector in the EntryPoint
public class App implements EntryPoint{
private final AppGinjector injector = GWT.create(AppGinjector.class);
public void onModuleLoad() {
AppPresenter aPres = injector.getAppPresenter();
aPres.bind();
RootPanel.get().add(aPres.getDisplay().asWidget());
PlaceManager placeManager = injector.getPlaceManager();
placeManager.fireCurrentPlace();
}
}
Step 5: Using Injector in the EntryPoint
public class App implements EntryPoint{
private final AppGinjector injector = GWT.create(AppGinjector.class);
public void onModuleLoad() {
AppPresenter aPres = injector.getAppPresenter();
aPres.bind();
RootPanel.get().add(aPres.getDisplay().asWidget());
PlaceManager placeManager = injector.getPlaceManager();
placeManager.fireCurrentPlace();
}
}
GWT generates the implementation of AppGinjector at compile time
Step 5: Using Injector in the EntryPoint
public class App implements EntryPoint{
private final AppGinjector injector = GWT.create(AppGinjector.class);
public void onModuleLoad() {
AppPresenter aPres = injector.getAppPresenter();
aPres.bind();
RootPanel.get().add(aPres.getDisplay().asWidget());
PlaceManager placeManager = injector.getPlaceManager();
placeManager.fireCurrentPlace();
}
}
GWT generates the implementation of AppGinjector at compile time
Here are all Interfaces. Their implementations are injected by GIN. But which implementation is bound to which Interface? => See AppClientModule .configure()
That’s it!
Learn more
Articles: • Google's MVP tutorial
• Best Practices For Architecting Your GWT App session
Projects: • Project google-gin
• Project google-guice
• Project gwt-dispatch
• Project gwt-presenter
• Project gwt-platform
• A project implement MVP patterns based on gwt-dispatch, gin, guice
• Apache Hupa – a GWT based webmail (using maven+junit+eclipse, gwt-dispatch, gwt-presenter, gin, guin). Highly recommended!
• TeampScape – Another tutorial projects about gwt+gae, gwt-dispatch, gwt-presenter, datastore/jdo
