使用Fresco时如何将图像保存到SD卡？

我在用Fresco http://frescolib.org/在我的应用程序中下载并显示 Gif。我想在单击时将图像保存到 SD 卡，但我不知道该怎么做。

final View view = inflater.inflate(R.layout.fragment_gif_viewer, container, false);
SimpleDraweeView draweeView = (SimpleDraweeView) view.findViewById(R.id.image);
Uri uri = Uri.parse(imageUrl);
DraweeController controller = Fresco.newDraweeControllerBuilder()
        .setUri(uri)
        .setAutoPlayAnimations(true)
        .build();
draweeView.setController(controller);

draweeView.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        // Save the gif to /sdcard/test.gif
    }
});

我尝试按照以下说明从 SimpleDraweeView 获取位图如何将 ImageView 保存为图像？ https://stackoverflow.com/questions/8262598/how-do-i-save-an-imageview-as-an-image，但它是getDrawingCache()返回空值

你可以这样做

ImageRequest downloadRequest = ImageRequest.fromUri(uri);
CacheKey cacheKey = DefaultCacheKeyFactory.getInstance().getEncodedCacheKey(downloadRequest);
if (ImagePipelineFactory.getInstance().getMainDiskStorageCache().hasKey(cacheKey)) {
    BinaryResource resource = ImagePipelineFactory.getInstance().getMainDiskStorageCache().getResource(cacheKey);
    File cacheFile = ((FileBinaryResource) resource).getFile();
    FileInputStream fis = new FileInputStream(cacheFile);
    ImageFormat imageFormat = ImageFormatChecker.getImageFormat(fis);
    switch (imageFormat) {
        case GIF:
        //copy cacheFile to sdcard
        break;
    }
}