baixar imagem e salvar na galeria?

Estou recebendo resposta do servidor e, na minha resposta, estou obtendo imagem, a exibição dessa resposta está no listview, agora o que quero é abaixo da imagem, tenho um botão para fazer o download da imagem e quero fazer o download dessa imagem e armazená-la em galeria .. abaixo é o meu código e resposta ..

Resposta JSON ..

 [
       {
      "b_card":"http:\/\/www.webname.com\/uploaded\/users\/vcard\/8_ers.jpg"
          }
       ]

MyBaseAdapter

 public class CustomAdapterBusinessCard extends BaseAdapter{


private static Bitmap bmp;
private Context context;
private ArrayList<HashMap<String,String>> listData;
private AQuery aQuery;

/*private static final String ADD_NAME="title_tag";
private static final String ADD_DESC="description";*/
private static final String ADD_IMAGE="b_card";




public CustomAdapterBusinessCard(Context context,ArrayList<HashMap<String,String>> listData) {
    this.context = context;
    this.listData=listData;
    aQuery = new AQuery(this.context);
}

@Override
public int getCount() {
    return listData.size();
}

@Override
public Object getItem(int position) {
    return listData.get(position);
}

@Override
public long getItemId(int position) {
    return position;
}


@Override
public View getView(final int position, View convertView, ViewGroup parent) {
    ViewHolder holder;
    if (convertView == null) {
        holder = new ViewHolder();
        convertView = LayoutInflater.from(context).inflate(R.layout.business_card, null);
        holder.propic = (ImageView) convertView.findViewById(R.id.imgvwbusinesscard);
        holder.btndownload=(Button) convertView.findViewById(R.id.dwnldbutton);
       // holder.txtproname = (TextView) convertView.findViewById(R.id.txtproducts);
       // holder.txtproid = (TextView) convertView.findViewById(R.id.txtproidsearch);
        //holder.txtprofilecast = (TextView) convertView.findViewById(R.id.txtproductsdescription);
       holder.btndownload.setOnClickListener(new OnClickListener() {

        private String url;

        @Override
        public void onClick(View v) {

            url = listData.get(position).get("b_card");
            System.out.println("cheking url"+url);
            new DownloadImageAsyncTask().execute();
            /*try {
                bmp = getBitmapFromUrl(url);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }*/

        }
    });


        convertView.setTag(holder);
    }else{
        holder = (ViewHolder) convertView.getTag();
    }


  /*  holder.txtproname.setText(listData.get(position).get(ADD_NAME));
    //holder.txtproid.setText(listData.get(position).get(TAG_PROFILE));
    holder.txtprofilecast.setText(listData.get(position).get(ADD_DESC));
   */

    holder.propic.setImageDrawable(Drawable.createFromPath(context.getExternalCacheDir() + File.separator
            + context.getResources().getString(R.string.app_name) + File.separator + "ImageName.png"));
    aQuery.id(holder.propic).image(listData.get(position).get(ADD_IMAGE),true,true,0,R.drawable.ic_launcher);



    // image parameter : 1 : memory cache,2:file cache,3:target width,4:fallback image
    return convertView;



}



class ViewHolder{
    ImageView propic;
    Button btndownload;
  //  TextView txtproname;
   // TextView txtproid;
  //  TextView txtprofilecast;



}
class DownloadImageAsyncTask extends AsyncTask<Void, Void, Void> 
{

         @Override
         protected Void doInBackground(Void... params)
         {
             // TODO Auto-generated method stub
             downloadImages();
             return null;
         }

         @Override
         protected void onPostExecute(Void result)
         {
             // TODO Auto-generated method stub
             super.onPostExecute(result);

         }

 }
private void downloadImages()
{

    URL imageUrl; //your URL from which image to be downloaded
    String domain;
    try
    {
        imageUrl = new URL("http://www.webname.com/web-service/b_card.php?user_id=8");

        HttpURLConnection urlConnection;
        try
        {
            urlConnection = (HttpURLConnection) imageUrl.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.setDoOutput(true);
            urlConnection.connect();
            String path = context.getExternalCacheDir() + File.separator + context.getResources().getString(R.string.app_name);
            File f = new File(path);
            if (!f.exists())
            {
                f.mkdirs();
            }
            File file = new File(f, "ImageName.png"); // Here you can save the image with name and extension
            if (!file.exists())
            {
                file.createNewFile();
            }
            FileOutputStream fileOutput = new FileOutputStream(file);
            InputStream inputStream = urlConnection.getInputStream();
            byte[] buffer = new byte[1024];
            int bufferLength = 0; // used to store a temporary size of the
                                    // buffer
            while ((bufferLength = inputStream.read(buffer)) > 0)
            {
                fileOutput.write(buffer, 0, bufferLength);
            }
            fileOutput.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

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

}

} Minha atividade

public class BusinessCard extends ListActivity{

private ArrayList<HashMap<String,String>> aList;

private String User_id;
JSONArray country_list=null;


private CustomAdapterBusinessCard adapter;
private ImageView bucard;
ImageLoader _DownImageLoader;

AQuery androidAQuery=new AQuery(this);
JSONArray state_list=null;
private static String BUSINESS_CARD_URL = "";
private static final String BUSINESS_CARD="b_card";

ArrayList<HashMap<String,String>> subcatagorydata;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.list_view_businesscard);

    User_id=this.getIntent().getStringExtra("userids");
    System.out.println("for business card"+User_id);


    BUSINESS_CARD_URL="http://www.webname.com/web-service/b_card.php?user_id="+User_id;




    bucard=(ImageView)findViewById(R.id.imgvwbusinesscard);


    new LoadBusiness().execute();


}

class LoadBusiness extends AsyncTask<String, String, ArrayList<HashMap<String,String>>> {

      ArrayAdapter<String> adaptercountry ;
    private ProgressDialog pDialog;
    private ArrayList<HashMap<String, String>> data;
    private String desc;
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(BusinessCard.this);
            pDialog.setMessage("Loading...");
            pDialog.setIndeterminate(false);
           // pDialog.setIndeterminateDrawable(getResources().getDrawable(R.drawable.custom_progress));
            pDialog.setCancelable(true);
            pDialog.show();

        }
        protected ArrayList<HashMap<String,String>> doInBackground(String... args) {
            ServiceHandler sh = new ServiceHandler();

            // Making a request to url and getting response
            data = new ArrayList<HashMap<String, String>>();
            String jsonStr = sh.makeServiceCall(BUSINESS_CARD_URL, ServiceHandler.GET);

            Log.d("Response: ", "> " + jsonStr);

            if (jsonStr != null) {
                try {
                    //JSONObject jsonObj = new JSONObject(jsonStr);

                    // Getting JSON Array node

                    //JSONArray data_array = new JSONArray(received);
                    country_list = new JSONArray(jsonStr);

                    // looping through All Contacts
                    for (int i = 0; i < country_list.length(); i++) {
                        JSONObject c = country_list.getJSONObject(i);
                        // creating new HashMap
                        HashMap<String, String> map = new HashMap<String, String>();
                        // adding each child node to HashMap key => value
                        map.put(BUSINESS_CARD, c.getString(BUSINESS_CARD));
                        /*map.put(PROFILE_VIEW_SUB_CATAGORY,c.getString(PROFILE_VIEW_SUB_CATAGORY));
                        map.put(PROFILE_VIEW_IMAGE,c.getString(PROFILE_VIEW_IMAGE));*/
                       // desc=country_list.getJSONObject(0).getJSONObject("description").toString();
                        /*JSONObject js=new JSONObject();
                        js.getString("description");
                        desc=js.toString();*/
                       // System.out.println("jsjsj"+desc);

                        data.add(map);

                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            } else {
                Log.e("ServiceHandler", "Couldn't get any data from the url");
            }

            return data;
        }
        protected void onPostExecute(ArrayList<HashMap<String,String>> result) {
            super.onPostExecute(result);
            pDialog.dismiss();


            if(aList == null)
            {
                aList = new ArrayList<HashMap<String, String>>();
                aList.addAll(result);
                adapter = new CustomAdapterBusinessCard(getBaseContext(), result);
                setListAdapter(adapter);
            }
            else
            {
                aList.addAll(result);
                adapter.notifyDataSetChanged();
            }
        }
 }

exibição de lista

   <RelativeLayout 
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@android:color/white"
 >

       <ListView 
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    android:id="@android:id/list"
    android:dividerHeight="1dp"

    ></ListView>


    </RelativeLayout>

listitem

   <LinearLayout 
        android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:orientation="vertical" >
      <ImageView 
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    android:id="@+id/imgvwbusinesscard"
    />
          <Button 
          android:layout_height="wrap_content"
          android:layout_width="wrap_content"
        android:text="Download"
        android:id="@+id/dwnldbutton"

      />

   </LinearLayout>

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