一、RxJava理論學習

a. 參考文章

http://gank.io/post/560e15be2dca930e00da1083#toc_28

http://gank.io/post/560e15be2dca930e00da1083

b. 含義

a library for composing asynchronous and event-based programs by using observable sequences. 一個在Java VM上使用可觀測的序列來組成異步的、基於事件的程序的庫。

特性： 擴展的觀察者模式、異步(線程控制)、變換(類型轉換)。

c. 簡單例子

通過一個url加載一張圖，恩為了演示RxJava和線程控制，我用HttpUrlConnection來做一個實例。

Observable.create(new Observable.OnSubscribe<Bitmap>() {
            @Override
            public void call(Subscriber<? super Bitmap> subscriber) {
                try {
                    URL url 
 
= new URL("http://img4.imgtn.bdimg.com/it/u=815679381,647288773&fm=21&gp=0.jpg");
                    HttpURLConnection connection = (HttpURLConnection) url.openConnection();
                    connection.setRequestMethod("GET");
                    connection.setConnectTimeout(8000);
                    connection.setReadTimeout(
 
8000);

                    InputStream in = connection.getInputStream();
                    Bitmap bitmap = BitmapFactory.decodeStream(in);
                    subscriber.onNext(bitmap);
                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
        })
                .observeOn(AndroidSchedulers.mainThread())  //指定subscriber的回調發生在UI線程
                .subscribeOn(Schedulers.newThread())        //指定subscribe()發生在新線程
                .subscribe(new Subscriber<Bitmap>() {
                    @Override
                    public void onCompleted() {
                        plan.setVisibility(View.GONE);
                    }

                    @Override
                    public void onError(Throwable e) {
                        e.printStackTrace();
                    }

                    @Override
                    public void onNext(Bitmap bitmap) {
                        if (bitmap != null) {
                            image.setImageBitmap(bitmap);
                            onCompleted();
                        }
                    }
                });
    }

知識樹雜談(2)