使用Fresco下载图片

    private void downLoadImg(Uri uri) {
        ImageRequest imageRequest = (uri).setProgressiveRenderingEnabled(true).build();
        ImagePipeline imagePipeline = ();
        DataSource<CloseableReference<CloseableImage>> dataSource = (imageRequest, this);
        (new BaseBitmapDataSubscriber() {
            @Override
            public void onNewResultImpl(@Nullable Bitmap bitmap) {
                //bitmap即为下载所得图片
            }

            @Override
            public void onFailureImpl(DataSource dataSource) {

            }
        }, ());

        GenericDraweeHierarchy hierarchy = new GenericDraweeHierarchyBuilder(getResources())
                .setFadeDuration(300)
//                .setPlaceholderImage(defaultDrawable)
//                .setFailureImage(defaultDrawable)
                .setProgressBarImage(new ProgressBarDrawable())
                .build();
        DraweeHolder<GenericDraweeHierarchy> draweeHolder = (hierarchy, this);

        PipelineDraweeController controller = (PipelineDraweeController) ()
                .setOldController(())
                .setImageRequest(imageRequest)
                .build();
        ();
    }