HexUtil.java

package com.foxinmy.weixin4j.util;

public final class HexUtil {
	/**
	 * Used to build output as Hex
	 */
	private static final char[] DIGITS_LOWER = { '0', '1', '2', '3', '4', '5',
			'6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

	/**
	 * Used to build output as Hex
	 */
	private static final char[] DIGITS_UPPER = { '0', '1', '2', '3', '4', '5',
			'6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

	private static char[] encodeHex(final byte[] data, final char[] toDigits) {
		final int l = data.length;
		final char[] out = new char[l << 1];
		// two characters form the hex value.
		for (int i = 0, j = 0; i < l; i++) {
			out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
			out[j++] = toDigits[0x0F & data[i]];
		}
		return out;
	}

	public static String encodeHexString(final byte[] data) {
		return new String(encodeHex(data, true));
	}

	public static char[] encodeHex(final byte[] data, final boolean toLowerCase) {
		return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
	}
}