从Google Guice获取通配符实例

Question

你好，我正在尝试Google Guice 5. x。我把我的类定义为：

public class Foo<T> {
    // some logic here
}

它也被用于其他课程，如：

public class Bar {

    private final Foo<Chocolate> provider;

    public Bar(Foo<Chocolate> _choco) {
        this.provider = _choco;
    }
}


public abstract class BaseZoo { // in some other package in a different jar

    private final Injector injector = Guice.createInjector(new MyAppModule());

    private Foo<?> provider;

    public String doSomething() {

        if (provider == null)
            this.provider = this.injector.getInstance(Foo.class);

        // some other code logic.
    } 
}

现在，在我的模块文件（MyAppModule）中，我将Foo定义为：

@Inject
@Provides
@Singleton
public Foo<Chocolate> getFoo(FooDependency fooDep) {
    return new Foo<>(fooDep);
}

现在，当我运行代码时，GoogleGuice能够找到Foo的实例

有没有办法配置GoogleGuice来解析Foo




Answer 1

绑定类型：

@Inject
@Provides
@Singleton
public Foo<?> getFoo(FooDependency fooDep) { ... }

如果你还想绑定Foo

bind(new Key<Foo<?>>() {}).to(new Key<Foo<Chocolate>>() {});

或者，使用提供者方法：

@Provides
Foo<?> provideWildcardFoo(Foo<Chocolate> chocolateFoo) {
  return chocolateFoo;
}