java - 如何从缓存文件的路径获取文件扩展名？

Question

我正在尝试保存 Glide 中缓存的文件以实现高效操作。

我获得了缓存文件的路径，并且它在 ImageView 中显示没有问题。

我需要缓存文件的扩展名来保存它。至少我是这样使用它的。

1.消息适配器。在聊天 Activity 中使用

 holder.imgHolder.setOnClickListener(new View.OnClickListener() { //using glide
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(mContext, ImageActivity.class);
            intent.putExtra("uri",chat.getImageUri());
            mContext.startActivity(intent);
        }
    });

ImageActivity//给他们一个大图像。

String cachedPath,fileExtention;    
Intent intent = getIntent();
imgUri = intent.getStringExtra("uri");

Log.e("glideUri", imgUri);//uri From server. if uri is same, Glide show cached file

AsyncTask.execute(new Runnable() { //get cached filePath in backroundThread
    @Override
    public void run() {
        cachedPath = getImgCachePath(imgUri); // retruns /data/user/0/com.devdev.Chatchat/cache/image_manager_disk_cache/c70aa7d94d9648c105a020f85d444182cc85ee298f0c1ec5aebe93c31984041b.0
        fileExtention = MimeTypeMap.getFileExtensionFromUrl(cachedPath);//returns 0
        Log.e("cachedPath", cachedPath);
        Log.e("fileExtention", fileExtention);
    }
});

new ClearSpTask(new ClearSpTask.AsynResponse() {//to know if AsyncTask is complete
    @Override
    public void processFinish(Boolean output) {

        Glide.with(ImageActivity.this).load(cachedPath).into(zoomImageView); //works well

        button_down.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.e("fileExtention", fileExtention); //returns 0;
                downImage(cachedPath); //works well if I set fileExtention manually. like jpg,gif
                Toast.makeText(ImageActivity.this, "Download complete", Toast.LENGTH_SHORT).show();
            }
        });
    }
}).execute();

getImgCachePath();

 private String getImgCachePath(String url) {

    FutureTarget<File> futureTarget = Glide.with(getBaseContext()).load(url).downloadOnly(100, 100);
    try {
        File file = futureTarget.get();
        String path = file.getAbsolutePath();
        return path;
    } catch (InterruptedException e) {
        e.printStackTrace();
    } catch (ExecutionException e) {
        e.printStackTrace();
    }
    return null;
}

downImage();

public  void downImage(String cachedUri){
        try
        {
            File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "kmChat" + System.currentTimeMillis() + "."+fileExtention);

            long startTime = System.currentTimeMillis();                

            InputStream is =new FileInputStream(cachedUri);                
            BufferedInputStream bis = new BufferedInputStream(is);               

            ByteArrayOutputStream baos = new ByteArrayOutputStream();

            byte[] img = new byte[1024];

            int current = 0;                
            while ((current = bis.read()) != -1) {
                baos.write(current);
            }         
            FileOutputStream fos = new FileOutputStream(file);
            fos.write(baos.toByteArray());               
            fos.flush();
            fos.close();
            is.close();

        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }

Answer 1

尝试使用FileProvider.getUriForFile。遵循以下思路的事情应该有望发挥作用。

Uri uri = FileProvider.getUriForFile(context, context.getPackageName(), file);

( reference )