update APK

atualizaApp = new UpdateApp();
atualizaApp.setContext(getApplicationContext());
atualizaApp.execute("http://serverurl/appfile.apk");

public class UpdateApp extends AsyncTask<String,Void,Void>{
    private Context context;
    public void setContext(Context contextf){
        context = contextf;
    }

    @Override
    protected Void doInBackground(String... arg0) {
        try {
            URL url = new URL(arg0[0]);
            HttpURLConnection c = (HttpURLConnection) url.openConnection();
            c.setRequestMethod("GET");
            c.setDoOutput(true);
            c.connect();

            String PATH = "/mnt/sdcard/Download/";
            File file = new File(PATH);
            file.mkdirs();
            File outputFile = new File(file, "update.apk");
            if(outputFile.exists()){
                outputFile.delete();
            }
            FileOutputStream fos = new FileOutputStream(outputFile);

            InputStream is = c.getInputStream();

            byte[] buffer = new byte[1024];
            int len1 = 0;
            while ((len1 = is.read(buffer)) != -1) {
                fos.write(buffer, 0, len1);
            }
            fos.close();
            is.close();

            Intent intent = new Intent(Intent.ACTION_VIEW);
            intent.setDataAndType(Uri.fromFile(new File("/mnt/sdcard/Download/update.apk")), "application/vnd.android.package-archive");
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); // without this flag android returned a intent error!
            context.startActivity(intent);


        } catch (Exception e) {
            Log.e("UpdateAPP", "Update error! " + e.getMessage());
        }
        return null;
    }
}