/**
   * RxJava实现加载loading效果图.
   * @param imageView 要显示的ImageView
   * @param color loading颜色
   * @param count 圆点的数量
   * @param period 动画播放间隔，单位为毫秒
   * @return 返回Disposable，用于取消动画
   */
  public static Disposable loading(final ImageView imageView, @ColorInt int color, final int count, long period) {
    final Bitmap bitmap = Bitmap.createBitmap(600, 600, Bitmap.Config.ARGB_4444);
    final Canvas canvas = new Canvas(bitmap);
    final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setStyle(Paint.Style.FILL);
    paint.setColor(color);
    canvas.translate(bitmap.getWidth() / 2, bitmap.getHeight() / 2);
    imageView.setImageBitmap(bitmap);
    final float angle = 360.0F / count;
    final int radius = 60;
    return Observable.interval(period, TimeUnit.MILLISECONDS).observeOn(AndroidSchedulers.mainThread())
        .subscribe(new Consumer<Long>() {
          @Override
          public void accept(Long aLong) throws Exception {
            canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
            canvas.rotate(angle);
            for (int i = 0; i < count; i++) {
              canvas.drawCircle(200, 0, radius - 5 * i, paint);
              canvas.rotate(angle);
            }
            imageView.setImageBitmap(bitmap);
          }
        });
  }

效果图如下所示：

loading.gif