无法将URL图像保存到Android studio emulator SD卡，打开失败：enoint（没有此类文件或目录）

我无法在我的android studio emulator SD卡上保存URL图像，我没有收到这样的文件和目录错误

/**
 * Background Async Task to download file
 * */
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/Download/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 = "/sdcard/Download/downloadedfile.jpg";
            // setting downloaded into image view
            my_image.setImageDrawable(Drawable.createFromPath(imagePath));
        }

    }
}

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尝试在AndroidManifest.xml中添加权限

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

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它已经存在了。我想问题与SD卡的路径有关。SD卡中是否有“/SD卡/下载”文件夹？首先创建文件夹。

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