java怎样实现十六进制字符串高低位转换

转成char[]，然后for循环+交换一下顺序，最后把char[]再转成string。
@Test
public void test_reverseHex() {
  Assert.assertEquals("23010A2E", reverseHex("2E0A0123"));
  Assert.assertEquals("2E0A0123", reverseHex(reverseHex("2E0A0123")));
}

private static String reverseHex(final String hex) {
  final char[] charArray = hex.toCharArray();
  final int length = charArray.length;
  final int times = length / 2;
  for (int c1i = 0; c1i < times; c1i += 2) {
    final int c2i = c1i + 1;
    final char c1 = charArray[c1i];
    final char c2 = charArray[c2i];
    final int c3i = length - c1i - 2;
    final int c4i = length - c1i - 1;
    charArray[c1i] = charArray[c3i];
    charArray[c2i] = charArray[c4i];
    charArray[c3i] = c1;
    charArray[c4i] = c2;
  }
  return new String(charArray);
}