Guice:绑定非即时依赖项

Question

这是我的课程：

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，这负责将MyService的请求注入MyServiceImpl实例。但是我不知道如何告诉 Guice 用 MyCommandImpl 配置 MyServiceImpl s，以及如何将 MyCommandImpl s 与 MyDAOImpl s 绑定。

Answer 1

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

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();
    }
}