AsyncTask経由で画像をダウンロードし、SDカードに保存せずにImageviewに表示

Question

AsyncTaskで画像をダウンロードして、ImageViewに表示したい場合は正常に処理できますが、 SDカードにファイルを保存しなくてもすべてを実行できます。

これまで私がこれまで行ってきたことは次のとおりです。

class DownloadFileFromURL extends AsyncTask<String, String, String> { 

/** 
* Before starting background thread 
* Show Progress Bar Dialog 
* */ 
@Override 
protected void onPreExecute() { 
    super.onPreExecute(); 
    showDialog(progress_bar_type); 
} 

/** 
* Downloading file in background thread 
* */ 
@Override 
protected String doInBackground(String... f_url) { 
    int count; 
    try { 
     URL url = new URL(f_url[0]); 
     URLConnection conection = url.openConnection(); 
     conection.connect(); 
     // getting file length 
     int lenghtOfFile = conection.getContentLength(); 

     // input stream to read file - with 8k buffer 
     InputStream input = new BufferedInputStream(url.openStream(), 8192); 

     // Output stream to write file 
     OutputStream output = new FileOutputStream("/sdcard/downloadedfile.jpg"); 

     byte data[] = new byte[1024]; 

     long total = 0; 

     while ((count = input.read(data)) != -1) { 
      total += count; 
      // publishing the progress.... 
      // After this onProgressUpdate will be called 
      publishProgress(""+(int)((total*100)/lenghtOfFile)); 

      // writing data to file 
      output.write(data, 0, count); 
     } 

     // flushing output 
     output.flush(); 

     // closing streams 
     output.close(); 
     input.close(); 

    } catch (Exception e) { 
     Log.e("Error: ", e.getMessage()); 
    } 

    return null; 
} 

/** 
* Updating progress bar 
* */ 
protected void onProgressUpdate(String... progress) { 
    // setting progress percentage 
    pDialog.setProgress(Integer.parseInt(progress[0])); 
} 

/** 
* After completing background task 
* Dismiss the progress dialog 
* **/ 
@Override 
protected void onPostExecute(String file_url) { 
    // dismiss the dialog after the file was downloaded 
    dismissDialog(progress_bar_type); 

    // Displaying downloaded image into image view 
    // Reading image path from sdcard 
    String imagePath = Environment.getExternalStorageDirectory().toString() + "/downloadedfile.jpg"; 
    // setting downloaded into image view 
    my_image.setImageDrawable(Drawable.createFromPath(imagePath)); 
} 

} 

Answer 1

をローカルにイメージをダウンロードしたくない場合は、あなたがByteArrayOutputStream代わりのFileOutputStreamを使用する必要があります。

そして、これはキーコードです：

ByteArrayOutputStream outputStream = new ByteArrayOutputStream(); 

byte data[] = new byte[1024]; 
long total = 0; 
while ((count = input.read(data)) != -1) { 
    total += count; 
    publishProgress(""+(int)((total*100)/lenghtOfFile)); 

    outputStream.write(data, 0, count); 
} 

//after downloading the image 
byte[] imageData = outputStream.toByteArray(); 
Bitmap bitmap = BitmapFactory.decodeByteArray(imageData, 0, imageData.length); 
my_image.setImageBitmap(bitmap); 

私はそれをテストしていないが、私は、これはあなたを助けることができると信じています。

Answer 2

代わりGlideを使用することができます。

Glide.with(this).load("http://server.com/image.jpg").into(imageView); 

Answer 3

参照Best method to download image from url in Android

private Bitmap downloadBitmap(String url) { 
     HttpURLConnection urlConnection = null; 
     try { 
      URL uri = new URL(url); 
      urlConnection = (HttpURLConnection) uri.openConnection(); 

      int statusCode = urlConnection.getResponseCode(); 
      if (statusCode != HttpStatus.SC_OK) { 
       return null; 
      } 

      InputStream inputStream = urlConnection.getInputStream(); 
      if (inputStream != null) { 

       Bitmap bitmap = BitmapFactory.decodeStream(inputStream); 
       return bitmap; 
      } 
     } catch (Exception e) { 
      Log.d("URLCONNECTIONERROR", e.toString()); 
      if (urlConnection != null) { 
       urlConnection.disconnect(); 
      } 
      Log.w("ImageDownloader", "Error downloading image from " + url); 
     } finally { 
      if (urlConnection != null) { 
       urlConnection.disconnect(); 

      } 
     } 
     return null; 
    }