URLConnection retourne toujours 400: mauvaise requête quand j'essaie de télécharger un.fichier wav

après avoir beaucoup trafiqué le code, j'ai trouvé un moyen de télécharger un fichier wav avec URLConnection, et en utilisant multipartentity. Voici le code, enjoy:

public int uploadWav(String sourceFileUri) {  
    String wavpath=Environment.getExternalStorageDirectory().getAbsolutePath()+"/myAppFolder/"+StorageUtils.AUDIO_FILE_NAME+".wav";
    String filename=wavpath;
    HttpURLConnection conn = null;
    DataOutputStream dos = null;  
    String lineEnd = "\r\n";
    String twoHyphens = "--";
    String boundary = "------------------------afb19f4aeefb356c";
    int bytesRead, bytesAvailable, bufferSize;
    byte[] buffer;
    int maxBufferSize = 1 * 1024 * 1024; 
    File sourceFile = new File(fileName); 
    Log.e("joshtag", "Uploading: sourcefileURI, "+fileName);

    if (!sourceFile.isFile()) {                                
         Log.e("uploadFile", "Source File not exist :"+wavpath);//FullPath);                        
         return 0;  //RETURN #1
         }
    else{
        try{        
             Log.v("joshtag","UPLOADING .WAV FILE");
             FileInputStream fileInputStream = new FileInputStream(sourceFile);   
             URL url = new URL(SERVER_URL);
             Log.v("joshtag","UL URL: "+url.toString());

             // Open a HTTP  connection to  the URL
             conn = (HttpURLConnection) url.openConnection(); 
             conn.setDoInput(true); // Allow Inputs
             conn.setDoOutput(true); // Allow Outputs
             conn.setUseCaches(false); // Don't use a Cached Copy            s       
             conn.setRequestMethod("POST");                     
            // conn.setRequestProperty("Connection", "Keep-Alive");
             conn.setRequestProperty("ENCTYPE", "multipart/form-data");
             conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);     
             conn.setRequestProperty("file", sourceFile.getName()); 
             //so on and so forth...
             //conn.setRequestProperty("param", "value");  
             conn.setRequestProperty("connection", "close");
             dos = new DataOutputStream(conn.getOutputStream());          
             dos.writeBytes(twoHyphens + boundary + lineEnd); 
             dos.writeBytes("Content-Disposition: form-data; name=\"file\";filename=\"" + sourceFile.getName() + "\"" + lineEnd);                    
             dos.writeBytes(lineEnd);      

             // create a buffer of  maximum size
             bytesAvailable = fileInputStream.available();           
             bufferSize = Math.min(bytesAvailable, maxBufferSize);
             buffer = new byte[bufferSize];         
             // read file and write it into form...
             bytesRead = fileInputStream.read(buffer, 0, bufferSize);   

             while (bytesRead > 0) {                        
                    dos.write(buffer, 0, bufferSize);
                    bytesAvailable = fileInputStream.available();
                    bufferSize = Math.min(bytesAvailable, maxBufferSize);
                    bytesRead = fileInputStream.read(buffer, 0, bufferSize);
                    Log.i("joshtag","->");
                    }
             Log.i("joshtag","->->");
             // send multipart form data necesssary after file data...
             dos.writeBytes(lineEnd);
             dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);
             conn.connect();
             Log.i("joshtag","->->->");
             // Responses from the server (code and message)
             serverResponseCode = conn.getResponseCode();
             Log.i("joshtag","->->->->");
             String serverResponseMessage = conn.getResponseMessage().toString();     

             Log.i("joshtag","->->->->->");
             Log.i("joshtag", "HTTP Response is : "  + serverResponseMessage + ": " + serverResponseCode);   

             // ------------------ read the SERVER RESPONSE
             DataInputStream inStream;
             String str="";
             String response="";
             try {
                 Log.i("joshtag","->->->->->->");
                 inStream = new DataInputStream(conn.getInputStream());

                 while ((str = inStream.readLine()) != null) {
                     Log.e("joshtag", "SOF Server Response" + str);
                     response=str;
                    }
                 inStream.close();
                }
             catch (IOException ioex) {
                Log.e("joshtag", "SOF error: " + ioex.getMessage(), ioex);
                }
             conn.disconnect();
             conn=null;                       
             //close the streams //
             fileInputStream.close();
             dos.flush();
             dos.close();    

             if(serverResponseCode == 201){       
                 loge("*** SERVER RESPONSE: 201"+response);
                }//END IF Response code 201  
            // conn.disconnect();
            }//END TRY - FILE READ      
        catch (MalformedURLException ex) {
            ex.printStackTrace();   
            Log.e("joshtag", "UL error: " + ex.getMessage(), ex);  
            } //CATCH - URL Exception

         catch (Exception e) {           
            e.printStackTrace();             
            Log.e("Upload file to server Exception", "Exception : "+ e.getMessage(), e);
            } 

        return serverResponseCode; //after try       
        }//END ELSE, if file exists.
    }