public String sendAndReceive(String srcUrl)
    {
        HttpURLConnection connection = null;
        InputStream in = null;
        try
        {
            URL url = new URL(srcUrl);
            connection = (HttpURLConnection)url.openConnection();
            connection.setRequestProperty("User-Agent", "Mozilla/MSIE");
            int contentLen = connection.getContentLength();
            in = connection.getInputStream();
            if(contentLen <= 0)
            {
                contentLen = bufLen;
                int offset = 0;
                do
                {
                    int len = in.read(buffer, offset, contentLen - offset);
                    if(len <= 0)
                        break;
                    offset += len;
                } while(true);
                contentLen = offset;
            } else
            {
                if(contentLen > bufLen)
                {
                    buffer = new byte[contentLen];
                    bufLen = contentLen;
                }
                int offset = 0;
                do
                {
                    int len = in.read(buffer, offset, contentLen - offset);
                    if(len <= 0)
                        break;
                    offset += len;
                } while(true);
                contentLen = offset;
            }
            String resMsg = connection.getHeaderField(0);
            if(resMsg.toLowerCase().indexOf("ok") < 0)
            {
                return null;
            } else
            {
                connection.disconnect();
                in.close();
                String content = new String(buffer, 0, contentLen);
                return content;
            }
        }
        catch(Exception e)
        {
            if(connection != null)
                connection.disconnect();
            if(in != null)
                try
                {
                    in.close();
                }
                catch(IOException ioexception) { }
            e.printStackTrace();
            return null;
        }
    }