public String sendFile(File file) throws IOException {
		try {
			fis = new DataInputStream(new BufferedInputStream(
					new FileInputStream(file)));
			out = new DataOutputStream(socket.getOutputStream());
			out.writeUTF(file.getName());
			out.flush();
			out.writeLong(file.length());
			out.flush();

			int bufferSize = 8192;
			byte[] buf = new byte[bufferSize];

			while (true) {
				int readState = 0;
				if (fis != null) {
					readState = fis.read(buf);
				}

				if (readState == -1) {
					break;
				}
				out.write(buf, 0, readState);
			}
			out.flush();
			return Feedback.OPERATION_SUCCEED.toString();
		} catch (IOException e) {
			if (out != null) {
				fis.close();
				out.close();
			}
			throw e;
		}
	}