java十六进制字符串和字节数组互转

public class HexUtil {
	/*
	 * Convert byte[] to hex
	 * string.这里我们可以将byte转换成int，然后利用Integer.toHexString(int)来转换成16进制字符串。
	 * 
	 * @param src byte[] data
	 * 
	 * @return hex string
	 */
	public static String bytesToHexString(byte[] src) {
		StringBuilder stringBuilder = new StringBuilder("");
		if (src == null || src.length <= 0) {
			return null;
		}
		for (int i = 0; i < src.length; i++) {
			int v = src[i] & 0xFF;
			String hv = Integer.toHexString(v);
			if (hv.length() < 2) {
				stringBuilder.append(0);
			}
			stringBuilder.append(hv);
		}
		return stringBuilder.toString().toUpperCase();
	}
	/**
	 * Convert hex string to byte[]
	 * 
	 * @param hexString
	 *            the hex string
	 * @return byte[]
	 */
	public static byte[] hexStringToBytes(String hexStr) {
		int index = 0;
		if (hexStr == null || hexStr.equals("")) {
			return null;
		}
		if (hexStr.startsWith("0x", index) || hexStr.startsWith("0X", index)) {
			index += 2;
		}
		hexStr = hexStr.substring(index).toUpperCase();
		int length = hexStr.length() / 2;
		char[] hexChars = hexStr.toCharArray();
		byte[] d = new byte[length];
		for (int i = 0; i < length; i++) {
			int pos = i * 2;
			d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));
		}
		return d;
	}
	/**
	 * Convert char to byte
	 * @param c
	 * char
	 * @return byte
	 */
	private static byte charToByte(char c) {
		byte b = (byte) "0123456789ABCDEF".indexOf(c);
		return b;
	}

	// 将指定byte数组以16进制的形式打印到控制台
	public static void printHexString(byte[] b) {
		for (int i = 0; i < b.length; i++) {
			String hex = Integer.toHexString(b[i] & 0xFF);
			if (hex.length() == 1) {
				hex = '0' + hex;
			}
			System.out.print(hex.toUpperCase());
		}
	}
	public static String bytes2HexString(byte[] b) {
		String ret = "";
		for (int i = 0; i < b.length; i++) {
			String hex = Integer.toHexString(b[i] & 0xFF);
			if (hex.length() == 1) {
				hex = '0' + hex;
			}
			ret += hex.toUpperCase();
		}
		return ret;
	}
	public static void main(String[] args) {
		String hex = "EFEF";
		byte[] a = hexStringToBytes(hex);
		String b = bytesToHexString(a);
		if(b.equals(hex)){
			System.out.println("ok");
		}else{
			System.out.println("no");
		}
	}
}