Downloading files using volley.

The files in android can be saved in either internal and external memories.By default, files saved to the internal storage are private to your application and other applications cannot access them (nor can the user). When the user uninstalls your application, these files are removed.

While files stored to the external storage are shareable and can be modified.

That is why the files that are specific for the application for example, additional resources downloaded by your app or temporary media files, are saved in internal storage. There are various ways to download a file but here we are going to download the file using volley.

Firstly you have to create your own custom request class like

class InputStreamVolleyRequest extends Request<byte[]> {
    private final Response.Listener<byte[]> mListener;
   private Map<String, String> mParams;

    //create a static map for directly accessing headers
   public Map<String, String> responseHeaders ;
 
    public InputStreamVolleyRequest(int method, String mUrl ,Response.Listener<byte[]> listener,
                                    Response.ErrorListener errorListener, HashMap<String, String> params) {
      // TODO Auto-generated constructor stub
       
        super(method, mUrl, errorListener);
         // this request would never use cache.
         setShouldCache(false);
         mListener = listener;
         mParams=params;
   }
 
   @Override
   protected Map<String, String> getParams()
         throws com.android.volley.AuthFailureError {
      return mParams;
   };
 
   
    @Override
    protected void deliverResponse(byte[] response) {
        mListener.onResponse(response);
    }
 
    @Override
    protected Response<byte[]> parseNetworkResponse(NetworkResponse response) {
 
        //Initialise local responseHeaders map with response headers received
        responseHeaders = response.headers;
 
        //Pass the response data here
        return Response.success( response.data, HttpHeaderParser.parseCacheHeaders(response));
    }
}

class InputStreamVolleyRequest extends Request<byte[]> {

private final Response.Listener<byte[]> mListener;

private Map<String, String> mParams;

//create a static map for directly accessing headers

public Map<String, String> responseHeaders ;

public InputStreamVolleyRequest(int method, String mUrl ,Response.Listener<byte[]> listener,

Response.ErrorListener errorListener, HashMap<String, String> params) {

// TODO Auto-generated constructor stub

super(method, mUrl, errorListener);

// this request would never use cache.

setShouldCache(false);

mListener = listener;

mParams=params;

}

@Override

protected Map<String, String> getParams()

throws com.android.volley.AuthFailureError {

return mParams;

};

@Override

protected void deliverResponse(byte[] response) {

mListener.onResponse(response);

}

@Override

protected Response<byte[]> parseNetworkResponse(NetworkResponse response) {

//Initialise local responseHeaders map with response headers received

responseHeaders = response.headers;

//Pass the response data here

return Response.success( response.data, HttpHeaderParser.parseCacheHeaders(response));

}

Now just send request though our custom class with Request.Method.GET and the url from where you want to doenload the file.

String mUrl= <YOUR_URL>;
InputStreamVolleyRequest request = new InputStreamVolleyRequest(Request.Method.GET, mUrl,
        new Response.Listener<byte[]>() { 
             @Override 
             public void onResponse(byte[] response) { 
           // TODO handle the response 
            try { 
            if (response!=null) {

              FileOutputStream outputStream;
              String name=<FILE_NAME_WITH_EXTENSION e.g reference.txt>;
                outputStream = openFileOutput(name, Context.MODE_PRIVATE);
                outputStream.write(response);
                outputStream.close();
                Toast.makeText(this, "Download complete.", Toast.LENGTH_LONG).show();
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            Log.d("KEY_ERROR", "UNABLE TO DOWNLOAD FILE");
            e.printStackTrace();
        }
  }
} ,new Response.ErrorListener() {

  @Override
  public void onErrorResponse(VolleyError error) {
    // TODO handle the error
    error.printStackTrace();
  }
}, null);
          RequestQueue mRequestQueue = Volley.newRequestQueue(getApplicationContext(), new HurlStack());
          mRequestQueue.add(request);

String mUrl= <YOUR_URL>;

InputStreamVolleyRequest request = new InputStreamVolleyRequest(Request.Method.GET, mUrl,

new Response.Listener<byte[]>() {

@Override

public void onResponse(byte[] response) {

// TODO handle the response

try {

if (response!=null) {

FileOutputStream outputStream;

String name=<FILE_NAME_WITH_EXTENSION e.g reference.txt>;

outputStream = openFileOutput(name, Context.MODE_PRIVATE);

outputStream.write(response);

outputStream.close();

Toast.makeText(this, "Download complete.", Toast.LENGTH_LONG).show();

}

} catch (Exception e) {

// TODO Auto-generated catch block

Log.d("KEY_ERROR", "UNABLE TO DOWNLOAD FILE");

e.printStackTrace();

}

} ,new Response.ErrorListener() {

@Override

public void onErrorResponse(VolleyError error) {

// TODO handle the error

error.printStackTrace();

}

}, null);

RequestQueue mRequestQueue = Volley.newRequestQueue(getApplicationContext(), new HurlStack());

mRequestQueue.add(request);

Now go to your application folder data/data/<your_application>/<file_name> and there is your file you can also download the file to external stoage.

You can access the files in internal storage using

Context.getFilesDir().<file_name>

1	Context.getFilesDir().<file_name>

It returns the file with that name from the internal directory of application and null if there is no file with such name. Dont forget to add extenion of the file with the name.

Aastha 14 October 2019

. . .

14 comments

Abir Hasan Jun 7, 2016 at 6:22 am

great tutorial, thanks 😀

aastha gupta Jul 12, 2016 at 1:23 pm
Thank you 😀

Reply

Muhammad Hamza Nov 18, 2016 at 9:06 am

Thanks for the tutorial.Cannot resolve function openFileOutput().Can please share the code for the function

Muhammad Hamza Nov 18, 2016 at 9:12 am
sorry my bad calling from an inner class have to use context.openFileOutput() issue resolved thanks any ways

Reply

Sakshi singhal Jul 23, 2018 at 12:14 pm

cant understand how to use it

Thais Sandim Jul 17, 2018 at 1:25 pm

Thank you!
Works fine

daddy Aug 25, 2018 at 12:31 am

“super(post, mUrl, errorListener);” should be “super(method, mUrl, errorListener);”

Mahdi Nov 24, 2018 at 3:05 am

Works like a charm 🙂 Thanks

Ranjithkumar R Oct 14, 2019 at 9:51 am

In our “custom request class” line no:12, “post” indicates which one?

anchit (Moderator) Oct 14, 2019 at 3:28 pm
Well actually the post is for the method integer that tell us the method type of the Http requestv (namely-> GET, POST).

I will correct the same in the content right away.

Reply