HexFormat是在Java 17中加入的:

String hex = HexFormat.of().formatHex(array);

对于固定长度，我会使用这样的东西，比如哈希值:

md5sum = String.format("%032x", new BigInteger(1, md.digest()));

为了完整起见，一个番石榴解决方案:

import com.google.common.io.BaseEncoding;
...
byte[] bytes = "Hello world".getBytes(StandardCharsets.UTF_8);
final String hex = BaseEncoding.base16().lowerCase().encode(bytes);

现在十六进制是“48656c6c6f20776f726c64”。

Converts bytes data to hex characters

@param bytes byte array to be converted to hex string
@return byte String in hex format

private static String bytesToHex(byte[] bytes) {
    char[] hexChars = new char[bytes.length * 2];
    int v;
    for (int j = 0; j < bytes.length; j++) {
        v = bytes[j] & 0xFF;
        hexChars[j * 2] = HEX_ARRAY[v >>> 4];
        hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
    }
    return new String(hexChars);
}

  public static byte[] hexStringToByteArray(String s) {
    int len = s.length();
    byte[] data = new byte[len / 2];
    for (int i = 0; i < len; i += 2) {
      data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
        + Character.digit(s.charAt(i+1), 16));
    }
  return data;
  } 

这是另一个使用Streams的方法:

private static String toHexString(byte[] bytes) {
    return IntStream.range(0, bytes.length)
    .mapToObj(i -> String.format("%02X", bytes[i]))
    .collect(Collectors.joining());
}