android - How to download file and store in sdcard? -

i working on should download file server , store in sdcard .

but getting exception : java.io.filenotfoundexception (permission denied)

public class mainactivity extends actionbaractivity {       // usually, subclasses of asynctask declared inside activity class.     // way, can modify ui thread here     private class downloadtask extends asynctask<string, integer, string> {          private context context;         private powermanager.wakelock mwakelock;         file file,sdcard;         public downloadtask(context context) {             this.context = context;         }          @override         protected string doinbackground(string... surl) {              system.out.print("background");             inputstream input = null;             outputstream output = null;             httpurlconnection connection = null;             try {                 url url = new url(surl[0]);                 connection = (httpurlconnection) url.openconnection();                 connection.connect();                  // expect http 200 ok, don't mistakenly save error report                 // instead of file                 if (connection.getresponsecode() != httpurlconnection.http_ok) {                     return "server returned http " + connection.getresponsecode()                             + " " + connection.getresponsemessage();                 }                  // useful display download percentage                 // might -1: server did not report length                 int filelength = connection.getcontentlength();                  // download file                 input = connection.getinputstream(); '        getting exception in line '                    output = new fileoutputstream("sdcard/file.mp3");                    byte data[] = new byte[4096];                 long total = 0;                 int count;                 while ((count = input.read(data)) != -1) {                     // allow canceling button                     if (iscancelled()) {                         input.close();                         return null;                     }                     total += count;                     // publishing progress....                     if (filelength > 0) // if total length known                         publishprogress((int) (total * 100 / filelength));                     output.write(data, 0, count);                 }             } catch (exception e) {                 return e.tostring();             } {                 try {                     if (output != null)                         output.close();                     if (input != null)                         input.close();                 } catch (ioexception ignored) {                 }                  if (connection != null)                     connection.disconnect();             }             return null;         } 

try this

file root = new file(environment.getexternalstoragedirectory(), "file.mp3");         if (!root.exists()) {             root.mkdirs();         } output = new fileoutputstream(root); 

and add permission on manifest file as

<uses-permission android:name="android.permission.write_external_storage" />