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Instance Injection Using Gin / Guice

I usually use this type of code in my GWT project:

Menu errorMenu = new Menu(user, userController, -1);
Menu  searchMenu = new Menu(user, userController, 0);

errorView.setMenu(errorMenu);
searchView.setMenu(searchMenu);

How I insert an instance Menuinto ErrorViewother "views" using Gin / Guice:

public ErrorView implements View {
 // Inject menu instance here
 private Menu menu;
}

So I don't need to manually create and set objects?

Also for the class Menu, how can I insert objects "user" and "userController", so I do not need to pass it to each instance of the menu every time it is created.

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1 answer

http://code.google.com/p/google-gin/wiki/GinTutorial . .

  • @ .

    public ErrorView implements View {

  @Inject
  private Menu menu;
}

public SearchView implements View {

  @Inject
  private Menu menu;
}

    View ( ). .

    public ErrorView implements View {

  private final Menu menu;

  @Inject
  public ErrorView(Menu menu) {
    this.menu = menu;
  }
}

public SearchView implements View {

  private final Menu menu;

  @Inject
  public SearchView(Menu menu) {
    this.menu = menu;
  }
}

    , , ErrorView, .

  • , GIN , ErrorView new Menu(user, userController, -1), - SearchView - new Menu(user, userController, 0). :

    • @Named("searchMenu") @Named("errorMenu") .

      public ErrorView implements View {

  @Inject
  @Named("errorMenu")
  private Menu menu;
}


      public ErrorView implements View {

  private final Menu menu;

  @Inject
  public ErrorView(@Named("errorMenu") Menu menu) {
    this.menu = menu;
  }
}

      GIN .

          public class ApplicationGinModule extends AbstractGinModule {

      protected void configure() {
        bind(Menu.class).annotatedWith(Names.named("errorMenu")).to(DefaultErrorMenu.class);
        bind(Menu.class).annotatedWith(Names.named("searchMenu")).to(DefaultSearchMenu.class);

        //assume that User and UserController classes have default constructors  
        //otherwise you should provide correct injection depending on your business-logic
        bind(User.class).in(Singleton.class); 
        bind(UserController.class).in(Singleton.class);  
      }
    }

    public class DefaultErrorMenu extends Menu {

      @Inject
      public DefaultErrorMenu(User user, UserController userController) {
        super(user, userController, -1);
      }
    }

    public class DefaultSearchMenu extends Menu {

      @Inject
      public DefaultSearchMenu(User user, UserController userController) {
        super(user, userController, 0);
      }
    }

    • @SearchMenu @ErrorMenu .

      :

      @Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.PARAMETER, ElementType.METHOD, ElementType.TYPE})
@BindingAnnotation
public @interface ErrorMenu {
}

      :

      public ErrorView implements View {

  @Inject
  @ErrorMenu
  private Menu menu;
}


      public ErrorView implements View {

  private final Menu menu;

  @Inject
  public ErrorView(@ErrorMenu Menu menu) {
    this.menu = menu;
  }
}

      , @Named ( "ErrorMenu" ):

      bind(Menu.class).annotatedWith(ErrorMenu.class).to(DefaultErrorMenu.class);

, , .

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