Question

早上好，我有以下代码从服务器下载bitmpa

/*SAVE IMAGE++++++++++++++++++++*/
    public void saveImage(Context context, Bitmap b, String imageName) {
        FileOutputStream foStream;
        try {
            foStream = context.openFileOutput(imageName, Context.MODE_PRIVATE);
            b.compress(Bitmap.CompressFormat.JPEG, 100, foStream);
            foStream.close();
            UPDTV_FOTO.setBackgroundColor(Color.GREEN);
            image.setImageBitmap(loadImageBitmap(getApplicationContext(), Giocatore));
            UPDTV_FOTO.setText("Download "+Giocatore+ " Complete");
        }  
        catch (FileNotFoundException e) { 
            Log.d("saveImage", "file not found"); 
            e.printStackTrace();
         //   UPDTV_FOTO.setText("FILE NOT FOUND");
        }  
        catch (IOException e) { 
            Log.d("saveImage", "io exception"); 
            e.printStackTrace();
          //  UPDTV_FOTO.setText("SAVE IMAGE ERROR");
        } 
    }
/*SAVE IMAGE+++++++++++++++++++++++++*/     


/*DOWNLOAD IMAGE++++++++++++++++++++++*/
    private class DownloadImage extends AsyncTask<String, Void, Bitmap> {
        private String TAG = "DownloadImage";
        private Bitmap downloadImageBitmap(String sUrl) {
            Bitmap bitmap = null;
            try {
                InputStream inputStream = new URL(sUrl).openStream();   // Download Image from URL
                bitmap = BitmapFactory.decodeStream(inputStream);       // Decode Bitmap
                inputStream.close();
            } catch (Exception e) {
                Log.d(TAG, "Exception 1, Something went wrong!");
                e.printStackTrace();
            //  UPDTV_FOTO.setText("DOWNLOAD ERROR");
            }
            return bitmap;
        }

        @Override
        protected Bitmap doInBackground(String... params) {
            return downloadImageBitmap(params[0]);
        }

        protected void onPostExecute(Bitmap result) {
            saveImage(getApplicationContext(), result, Giocatore);
        }
    }
/*DOWNLOAD IMAGE++++++++++++++++++++++*/        


/*LOAD IMAGE*+++++++++++++++++++++++++++++++++++++*/
    public Bitmap loadImageBitmap(Context context, String imageName) {
        Bitmap bitmap = null;
        FileInputStream fiStream;
        try {
            fiStream    = context.openFileInput(imageName);
            bitmap      = BitmapFactory.decodeStream(fiStream);
            fiStream.close();
        } catch (Exception e) {
            Log.d("saveImage", "Exception 3, Something went wrong!");
            e.printStackTrace();
        //  UPDTV_FOTO.setText("LOAD ERROR");
        }
        return bitmap;
    }
    /*LOAD IMAGE+++++++++++++++++++++++++++*/

如果我尝试下载的位图在服务器上可用，则所有工作正常

new DownloadImage().execute(myurl);

否则如果不可用，我的应用程序崩溃了。所以我想在开始下载之前检查servere上是否有位图。

我试试

if (URLUtil.isValidUrl(URL+FotoGiocatore)==true);

以及

How can I programmatically test an HTTP connection?

Check if file exists on remote server using its URL

Answer 1

您还可以使用以下代码检查图像是否存在

URL url = new URL("YOUR URL");
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");

urlConnection.connect();

`int status = urlConnection.getResponseCode();`

并且仅在status==200

时才开始下载

在开始下载之前检查服务器上是否存在位图

1 个答案: