java - Guice:绑定(bind)非直接依赖项

Question

这是我的类(class):

public interface MyService {
    // ...
}

public class MyServiceImpl implements MyService {
    private MyCommand myCommand;
}

public interface MyCommand {
    // ...
}

public class MyCommandImpl implements MyCommand {
    private MyDAO myDAO;
}

public interface MyDAO {
    // ...
}

public class MyDAOImpl implements MyDAO {
    // ...
}

public class MyModule extends AbstractModule {
    @Override
    protected void configure() {
        bind(MyService.class).to(MyServiceImpl.class)
    }
}

public class MyDriver {
    @Inject
    private MyService myService;

    public static void main(String[] args) {
        MyModule module = new MyModule();
        Injector injector = Guice.createInjector(module);
        MyDriver myDriver = injector.getInstance(MyDriver.class);

        // Should have been injected with a MyServiceImpl,
        // Which should have been injected with a MyCommandImpl,
        // Which should have been injected with a MyDAOImpl.
        myDriver.getMyService().doSomething();
    }
}

因此，这负责使用 MyServiceImpl 实例注入(inject)对 MyService 的请求。但我不知道如何告诉 Guice 使用 MyCommandImpl 配置 MyServiceImpl，以及如何将 MyCommandImpl 与 MyDAOImpl 绑定(bind)s。

Answer 1

您需要的其他绑定(bind)和注入(inject)应该像第一个一样设置。在需要实例的地方使用 @Inject，并将接口(interface)绑定(bind)到模块中的 impl。我在下面添加了 4 行(注释了 2 个注入(inject)位点并定义了另外 2 个绑定(bind)):

public interface MyService {
    // ...
}

public class MyServiceImpl implements MyService {
    @Inject
    private MyCommand myCommand;
}

public interface MyCommand {
    // ...
}

public class MyCommandImpl implements MyCommand {
    @Inject
    private MyDAO myDAO;
}

public interface MyDAO {
    // ...
}

public class MyDAOImpl implements MyDAO {
    // ...
}

public class MyModule extends AbstractModule {
    @Override
    protected void configure() {
        bind(MyService.class).to(MyServiceImpl.class);
        bind(MyCommand.class).to(MyCommandImpl.class);
        bind(MyDAO.class).to(MyDAOImpl.class);
    }
}

public class MyDriver {
    @Inject
    private MyService myService;

    public static void main(String[] args) {
        MyModule module = new MyModule();
        Injector injector = Guice.createInjector(module);
        MyDriver myDriver = injector.getInstance(MyDriver.class);

        // Should have been injected with a MyServiceImpl,
        // Which should have been injected with a MyCommandImpl,
        // Which should have been injected with a MyDAOImpl.
        myDriver.getMyService().doSomething();
    }
}