java - 如何创建自定义订阅服务器？

我想在progressDialog下载文件时显示observable，完成后想将文件发送给订户。

我试图通过扩展Subscriber来使我的自定义订阅者成为:

public abstract class MySubscriber<T> extends Subscriber {
    abstract void onMessage(String message);
    abstract void onDownloaded(File file);
}

并尝试订阅:
`

MySubscriber mySubscriber = new MySubscriber() {
            @Override
            public void onMessage(String message) {
                progessDialog.setMessage(message);
            }

            @Override
            public void onCompleted() {

            }

            @Override
            public void onError(Throwable e) {

            }

            @Override
            public void onNext(Object o) {

            }
        };

observable.subscribe(mySubscriber);
可观察到的是:

observable  = Observable.create(new Observable.OnSubscribe<Void>() {
            @Override
            public void call(Subscriber<Void> subscriber) {
                 //file downloading code...
                if (subscriber instanceof MySubscriber){
                ((MySubscriber) subscriber).onMessage("100%");
                ((MySubscriber) subscriber).onDownloaded(file);
               }else{
                   Log.e(TAG,"subscriber is not instance of MySubscriber")
                }
             }

答案是“订户不是MySubscriber的实例”

最佳答案

subscriber不属于MySubscriber类型的原因是，您传递的实例最终被subscribe()包装在 SafeSubscriber 中:

private static <T> Subscription subscribe(Subscriber<? super T> subscriber, Observable<T> observable) {
    ...
        if(!(subscriber instanceof SafeSubscriber)) {
            subscriber = new SafeSubscriber((Subscriber)subscriber);
        }
    ...
    }
}

如果您想继续使用您的方法，可以将subscriber转换为SafeSubscriber并对其调用SafeSubscriber#getActual()以获得MySubscriber实例。

在您的情况下:

Observable.create(new Observable.OnSubscribe<Void>() {
    @Override
    public void call(Subscriber<? super Void> subscriber) {
        Subscriber yourSubscriber = ((SafeSubscriber) subscriber).getActual();
        ((MySubscriber) yourSubscriber).onMessage("100%");
        ((MySubscriber) yourSubscriber).onDownloaded(file);
    }
});