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

HexFormat是在Java 17中加入的:

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

其他回答

这个怎么样?

    String byteToHex(final byte[] hash)
    {
        Formatter formatter = new Formatter();
        for (byte b : hash)
        {
            formatter.format("%02x", b);
        }
        String result = formatter.toString();
        formatter.close();
        return result;
    }

我更喜欢用这个:

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

它是对公认答案的稍微灵活的改编。 就我个人而言,我既保留了公认的答案,也保留了这个重载,以便在更多的环境中使用。

public static String toHexString(byte[] bytes) {

    StringBuilder sb = new StringBuilder();

    if (bytes != null) 
        for (byte b:bytes) {

            final String hexString = Integer.toHexString(b & 0xff);

            if(hexString.length()==1)
                sb.append('0');

            sb.append(hexString);//.append(' ');
        }

      return sb.toString();//.toUpperCase();
}

使用DatatypeConverter:

public String toHexString(byte... bytes) {

    return Optional.ofNullable(bytes)
            .filter(bs->bs.length>0)
            .map(DatatypeConverter::printHexBinary)
            .map(str->IntStream.range(0, str.length())
                    .filter(i->(i%2)==0)        // take every second index
                    .mapToObj(i->"0x" + str.substring(i, i+2))
                    .collect(Collectors.joining(" ")))
            .orElse("");
}

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=[])

在存储查找表的很小代价下,这个实现非常简单和快速。

 private static final char[] BYTE2HEX=(
    "000102030405060708090A0B0C0D0E0F"+
    "101112131415161718191A1B1C1D1E1F"+
    "202122232425262728292A2B2C2D2E2F"+
    "303132333435363738393A3B3C3D3E3F"+
    "404142434445464748494A4B4C4D4E4F"+
    "505152535455565758595A5B5C5D5E5F"+
    "606162636465666768696A6B6C6D6E6F"+
    "707172737475767778797A7B7C7D7E7F"+
    "808182838485868788898A8B8C8D8E8F"+
    "909192939495969798999A9B9C9D9E9F"+
    "A0A1A2A3A4A5A6A7A8A9AAABACADAEAF"+
    "B0B1B2B3B4B5B6B7B8B9BABBBCBDBEBF"+
    "C0C1C2C3C4C5C6C7C8C9CACBCCCDCECF"+
    "D0D1D2D3D4D5D6D7D8D9DADBDCDDDEDF"+
    "E0E1E2E3E4E5E6E7E8E9EAEBECEDEEEF"+
    "F0F1F2F3F4F5F6F7F8F9FAFBFCFDFEFF").toCharArray();
   ; 

  public static String getHexString(byte[] bytes) {
    final int len=bytes.length;
    final char[] chars=new char[len<<1];
    int hexIndex;
    int idx=0;
    int ofs=0;
    while (ofs<len) {
      hexIndex=(bytes[ofs++] & 0xFF)<<1;
      chars[idx++]=BYTE2HEX[hexIndex++];
      chars[idx++]=BYTE2HEX[hexIndex];
    }
    return new String(chars);
  }