Downloading a file by clicking on the button, how to do? [closed]

create an AppController file

import android.app.Application; import android.text.TextUtils; import com.android.volley.Request; import com.android.volley.RequestQueue; import com.android.volley.toolbox.Volley; public class AppController extends Application { public static final String TAG = AppController.class.getSimpleName(); private RequestQueue mRequestQueue; private static AppController mInstance; @Override public void onCreate() { super.onCreate(); mInstance = this; } public static synchronized AppController getInstance() { return mInstance; } public RequestQueue getRequestQueue() { if (mRequestQueue == null) { mRequestQueue = Volley.newRequestQueue(getApplicationContext()); } return mRequestQueue; } public <T> void addToRequestQueue(Request<T> req, String tag) { req.setTag(TextUtils.isEmpty(tag) ? TAG : tag); getRequestQueue().add(req); } } 

Add to manifest

 <application android:name=".AppController" ... /> 

Add to build.gradle

 dependencies { ... compile 'com.mcxiaoke.volley:library-aar:1.0.0' } 

And finally, the method call itself, it works asynchronously, so you do not need to give it AsyncTask or something else, below is an example for the line, you can also create a method for another file by reference .

 String tag_string_req = "request"; final ProgressDialog progressDialog = new ProgressDialog(getContext()); progressDialog.setMessage("Подключение к серверу. Подождите..."); progressDialog.setIndeterminate(false); progressDialog.setCancelable(false); progressDialog.show(); StringRequest strReq = new StringRequest(Request.Method.POST, url, new Response.Listener<String>() { @Override public void onResponse(String response) { progressDialog.dismiss(); Log.d("response",response); }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { progressDialog.dismiss(); AlertDialog.Builder alert = new AlertDialog.Builder(getContext()); alert.setTitle("Ошибка авторизации"); final TextView input = new TextView(getContext()); alert.setView(input); input.setTextSize(TypedValue.COMPLEX_UNIT_SP, 17); input.setPadding(20, 10, 20, 10); input.setTextColor(ContextCompat.getColor(getContext(), android.R.color.black)); input.setText("Ошибка"); alert.setPositiveButton("OK", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int whichButton) { } }); alert.show(); } }) { @Override protected Map<String, String> getParams() { //Записываем параметры в запрос который передаем на сервер Map<String, String> params = new HashMap<>(); params.put("param", param); return params; } }; AppController.getInstance().addToRequestQueue(strReq, tag_string_req);