/**
 *Description: encapsule http protocol of uploading.
 *@param url  The server url of handleing upload.
 *@param sessionId  Session id
 *@param uploadFile The file that is going to be uploaded
 *@param param Other form parameters
 *@return
 *@throws
 */
public static void doMultipartUpload( String url,  String sessionId, 
             File uploadFile,  Map<String, String> param, 
             UploadApplet applet,  List<Map<String, String>> fileList,
             int index) {
       
                long blockSize = 5*MB;
                int rate = 0;
                long fileSize = uploadFile.length();
               
                long uploadCount = ((long)(fileSize - 1)/blockSize) + 1;
                System.out.println("before loop ..................."+fileSize+"....."+ uploadCount);
                param.put("mu", "1");
                List<Map<String, String>> fList = fileList;
                Map<String, String> fm = (Map)fList.get(index);
                for(long i = 0 ; i < uploadCount; i++) {
                    param.put("n", "" + i);
                    doMultipartUploadOne(url,i,blockSize, sessionId, uploadFile,param);
                    rate = (int)((float)i / (float)uploadCount * 100);
                    fm.put("RATE", ""+rate);
                    updateUploadInfo(applet, fList);
                }
                fm.put("RATE", "100");
                updateUploadInfo(applet, fList);
            
    }
    
    /**
     * 
     */
    public static void doMultipartUploadOne(String url,long n, long blockSize, String sessionId, File uploadFile, Map param) {
      try {
        long skip = n * blockSize;
        RandomAccessFile fin = new RandomAccessFile(uploadFile, "r");
        fin.seek(skip);
        long fileSize = fin.length();
        long uploadSize = (skip + blockSize > fileSize) ? fileSize - skip : blockSize;
        URL u = new URL(url);
        byte[] form_part = getFormData(param);
        byte[] end_data = ("\r\n--" + boundary + "--\r\n").getBytes();   
        long size = form_part.length + uploadSize + end_data.length;
        HttpURLConnection con = (HttpURLConnection)u.openConnection();
        con.setRequestMethod("POST");
        con.setDoInput(true);
        con.setDoOutput(true);
        con.addRequestProperty("Cookie","JSESSIONID="+sessionId);
        con.addRequestProperty("Connection","Keep-Alive");
        con.addRequestProperty("Cache-Control", "no-cache");
        con.setRequestProperty("Content-Type","multipart/form-data; boundary="+boundary);
        con.setRequestProperty("Content-Length",String.valueOf(size));
        DataOutputStream out = new DataOutputStream(con.getOutputStream());
        out.write(form_part);
        StringBuffer headerBuf = new StringBuffer();
        headerBuf.append("Content-Disposition: form-data; name=\"file\"; filename=\"")
                 .append(uploadFile.getAbsolutePath()).append("\"\r\n");
        headerBuf.append("Content-Type: application/octet-stream\r\n\r\n"); 
        out.write(headerBuf.toString().getBytes());
        int rn2 = 0;
        long loadLen = 0L;
        byte[] buf2 = new byte[1024];   
        while((rn2=fin.read(buf2, 0, 1024))>0)   
        {   
            if(loadLen + rn2 >= blockSize){
                out.write(buf2,0,