android - 无法使用 Volley 从 Json 响应保存图像

Question

在 Android 中从 ImageView 保存图像不起作用。通过 Volley 从 JSON 加载图像。我想将该图像保存在图库中，但在某些设备上此代码不起作用。

BitmapDrawable draw = (BitmapDrawable) thumbnail.getDrawable();
Bitmap bitmap = draw.getBitmap();

FileOutputStream outStream = null;

File dir = new File(Environment.getExternalStorageDirectory() + "");
dir.mkdirs();
String fileName = String.format("%d.jpg", System.currentTimeMillis());
File outFile = new File(dir, fileName);
try {
     outStream = new FileOutputStream(outFile);
     } catch (FileNotFoundException e) {
       e.printStackTrace();
       }
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, outStream);
try {
     outStream.flush();
     } catch (IOException e) {
        e.printStackTrace();
    }
    try {
      outStream.close();
      } catch (IOException e) {
      e.printStackTrace();
    }
Toast.makeText(JobsDetail.this, "Download Successfully", Toas.LENGTH_SHORT).show();
Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
intent.setData(Uri.fromFile(dir));
sendBroadcast(intent);

Answer 1

只需使用它直接从图像网址下载

// DownloadImage AsyncTask
    private class DownloadImage extends AsyncTask<String, Void, Bitmap> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            progressBar.setVisibility(View.VISIBLE);

        }

        @Override
        protected Bitmap doInBackground(String... URL) {

            String imageURL = URL[0];

            Bitmap bitmap = null;
            try {
                // Download Image from URL
                InputStream input = new java.net.URL(imageURL).openStream();
                // Decode Bitmap
                bitmap = BitmapFactory.decodeStream(input);
            } catch (Exception e) {
                e.printStackTrace();
            }
            return bitmap;
        }

        @Override
        protected void onPostExecute(Bitmap result) {

                if (result != null) {
                    progressBar.setVisibility(View.GONE);

                    File destination = new File(Environment.getExternalStorageDirectory(),
            System.currentTimeMillis() + ".jpg");
                    try {
                        destination.createNewFile();
                        ByteArrayOutputStream bos = new ByteArrayOutputStream();
                        result.compress(Bitmap.CompressFormat.PNG, 0 /*ignored for PNG*/, bos);
                        byte[] bitmapdata = bos.toByteArray();

                        FileOutputStream fos = new FileOutputStream(destination);
                        fos.write(bitmapdata);
                        fos.flush();
                        fos.close();
                        LicenseFrontFile = destination;
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }

            // Set the bitmap into ImageView

            //image.setImageBitmap(result);
            // Close progressdialog

    }

要使用，请这样调用

new DownloadImage().execute(image_url);

还在 list 中添加写入权限

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

以及 Marshmallow 或以上设备的运行时权限