private String readLine(BufferedReader clientRequest) {
		String clientCommand = null;
		this.log.info("before read Line");
		do {
			if (this.currentThread.isInterrupted()) {
				this.log.info("current Thread is Interrupted");
				closeClientSocket();
				this.log.info("ClientHandler " + id + " finish");
				return null;
			}
			try {
				clientCommand = clientRequest.readLine();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				this.log.info("read Line: fail");
			}
		} while (clientCommand == null);
		return clientCommand;
	}