@Override
public void run() {
   try {
       System.out.println("start download");

       URL httpUrll = new URL(url);
       HttpURLConnection httpURLConnection = (HttpURLConnection) httpUrll.openConnection();

       httpURLConnection.setDoInput(true);
       httpURLConnection.setDoOutput(true);

       InputStream inputStream;
       if (httpURLConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
           inputStream = httpURLConnection.getInputStream();
       } else {
           inputStream = httpURLConnection.getErrorStream();
           System.out.println("error＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋＋");
       }

       FileOutputStream fileOutputStream = null;

       File downloadFile;
       File sdkFile;
       if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
           downloadFile = Environment.getExternalStorageDirectory();
           sdkFile = new File(downloadFile, "test.apk");

           fileOutputStream = new FileOutputStream(sdkFile);
       }

       byte[] bytes = new byte[6 * 1024];
       int length;

       System.out.println("is here");

       while ((length = inputStream.read(bytes)) != -1) {
           if (fileOutputStream != null) {
               fileOutputStream.write(bytes, 0, length);
           }
       }

       if (fileOutputStream != null) {
           fileOutputStream.close();
       }

       if (inputStream != null) {
           inputStream.close();
       }

       System.out.println("download success");


   } catch (MalformedURLException e) {
       e.printStackTrace();
   } catch (IOException e) {
       e.printStackTrace();
   }
}