public class HexStringUtils {
	private static final char[] DIGITS_HEX = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D',
			'E', 'F' };
	protected static char[] encodeHex(byte[] data) {
		int l = data.length;
		char[] out = new char[l << 1];
		for (int i = 0, j = 0; i < l; i++) {
			out[j++] = DIGITS_HEX[(0xF0 & data[i]) >>> 4];
			out[j++] = DIGITS_HEX[0x0F & data[i]];
		}
		return out;
	}
	protected static byte[] decodeHex(char[] data) {
		int len = data.length;
		if ((len & 0x01) != 0) {
			throw new RuntimeException("字符个数应该为偶数");
		}
		byte[] out = new byte[len >> 1];
		for (int i = 0, j = 0; j < len; i++) {
			int f = toDigit(data[j], j) << 4;
			j++;
			f |= toDigit(data[j], j);
			j++;
			out[i] = (byte) (f & 0xFF);
		}
		return out;
	}
	protected static int toDigit(char ch, int index) {
		int digit = Character.digit(ch, 16);
		if (digit == -1) {
			throw new RuntimeException("Illegal hexadecimal character " + ch + " at index " + index);
		}
		return digit;
	}
	public static String toHex(String str) {
		return new String(encodeHex(str.getBytes()));
	}
	public static String fromHex(String hex) {
		return new String(decodeHex(hex.toCharArray()));
	}
	public static void main(String[] args) {
		String s = "abc你好";
		String hex = toHex(s);
		String decode = fromHex(hex);
		System.out.println("原字符串:" + s);
		System.out.println("十六进制字符串:" + hex);
		System.out.println("还原:" + decode);
	}
}

public class TimeServer {
	public static void main(String[] args) throws IOException {
		int port = 1234;
		ServerSocket server = null;
		try {
			server = new ServerSocket(port);
			System.out.println("The time server is listening in port : " + port);
			Socket socket = null;
			while (true) {
				socket = server.accept();
				new Thread(new TimeServerHandler(socket)).start();
			}
		} finally {
			if (server != null) {
				System.out.println("The time server close");
				server.close();
				server = null;
			}
		}
	}
}