我有一个字节数组充满十六进制数字和打印它的简单方式是相当没有意义的,因为有许多不可打印的元素。我需要的是精确的十六进制形式:3a5f771c


当前回答

如果你想让它更具可读性,并将字节彼此分开,你可以在Java 17+中使用以下代码:

byte[] yourByteArray = { -128, 0, 127 };
String hexString = new String(HexFormat.ofDelimiter(" ").formatHex(yourByteArray));
// 80 00 7f

其他回答

我们不需要使用任何外部库,也不需要基于循环和常量编写代码。 这样就够了:

byte[] theValue = .....
String hexaString = new BigInteger(1, theValue).toString(16);

javax.xml.bind.DatatypeConverter.printHexBinary()方法是用于XML绑定的Java体系结构(JAXB)的一部分,是将字节[]转换为十六进制字符串的方便方法。DatatypeConverter类还包括许多其他有用的数据操作方法。

在Java 8和更早的版本中,JAXB是Java标准库的一部分。它在Java 9中被弃用,在Java 11中被移除,这是将所有Java EE包移动到它们自己的库中的努力的一部分。说来话长。现在,javax.xml.bind还不存在,如果希望使用包含DatatypeConverter的JAXB,则需要从Maven安装JAXB API和JAXB运行时。

使用示例:

byte bytes[] = {(byte)0, (byte)0, (byte)134, (byte)0, (byte)61};
String hex = javax.xml.bind.DatatypeConverter.printHexBinary(bytes);

会导致:

000086003D

这个和这个答案是一样的。

  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;
  } 

从这里的讨论,特别是这个答案,这是我目前使用的函数:

private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
public static String bytesToHex(byte[] bytes) {
    char[] hexChars = new char[bytes.length * 2];
    for (int j = 0; j < bytes.length; j++) {
        int v = bytes[j] & 0xFF;
        hexChars[j * 2] = HEX_ARRAY[v >>> 4];
        hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
    }
    return new String(hexChars);
}

My own tiny benchmarks (a million bytes a thousand times, 256 bytes 10 million times) showed it to be much faster than any other alternative, about half the time on long arrays. Compared to the answer I took it from, switching to bitwise ops --- as suggested in the discussion --- cut about 20% off of the time for long arrays. (Edit: When I say it's faster than the alternatives, I mean the alternative code offered in the discussions. Performance is equivalent to Commons Codec, which uses very similar code.)

2k20版本,相对于Java 9的压缩字符串:

private static final byte[] HEX_ARRAY = "0123456789ABCDEF".getBytes(StandardCharsets.US_ASCII);
public static String bytesToHex(byte[] bytes) {
    byte[] hexChars = new byte[bytes.length * 2];
    for (int j = 0; j < bytes.length; j++) {
        int v = bytes[j] & 0xFF;
        hexChars[j * 2] = HEX_ARRAY[v >>> 4];
        hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
    }
    return new String(hexChars, StandardCharsets.UTF_8);
}

如果您正在为python寻找一模一样的字节数组,我已经将这个Java实现转换为python。

class ByteArray:

@classmethod
def char(cls, args=[]):
    cls.hexArray = "0123456789ABCDEF".encode('utf-16')
    j = 0
    length = (cls.hexArray)

    if j < length:
        v = j & 0xFF
        hexChars = [None, None]
        hexChars[j * 2] = str( cls.hexArray) + str(v)
        hexChars[j * 2 + 1] = str(cls.hexArray) + str(v) + str(0x0F)
        # Use if you want...
        #hexChars.pop()

    return str(hexChars)

array = ByteArray()
print array.char(args=[])