For logging purpose we are converting the logs to byte array and then to hex string. I want to get it back in a Java String, but I am not able to do so.
The hex string in log file looks something like
fd00000aa8660b5b010006acdc0100000101000100010000
How can I decode this?
Using Hex in Apache Commons:
String hexString = "fd00000aa8660b5b010006acdc0100000101000100010000";
byte[] bytes = Hex.decodeHex(hexString.toCharArray());
System.out.println(new String(bytes, "UTF-8"));
<dependency> <groupId>commons-codec</groupId> <artifactId>commons-codec</artifactId> <version>1.12</version> </dependency>
new String(bytes, "UTF-8") will just produce garbage.
byte[] bytes = javax.xml.bind.DatatypeConverter.parseHexBinary(hexString);
String result= new String(bytes, encoding);
DatatypeConverter?
You can go from String (hex) to byte array to String as UTF-8(?). Make sure your hex string does not have leading spaces and stuff.
public static byte[] hexStringToByteArray(String hex) {
int l = hex.length();
byte[] data = new byte[l / 2];
for (int i = 0; i < l; i += 2) {
data[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4)
+ Character.digit(hex.charAt(i + 1), 16));
}
return data;
}
Usage:
String b = "0xfd00000aa8660b5b010006acdc0100000101000100010000";
byte[] bytes = hexStringToByteArray(b);
String st = new String(bytes, StandardCharsets.UTF_8);
System.out.println(st);
First of all read in the data, then convert it to byte array:
byte b = Byte.parseByte(str, 16);
and then use String constructor:
new String(byte[] bytes)
or if the charset is not system default then:
new String(byte[] bytes, String charsetName)
Byte.parseByte(str, 16); to parse a hexadecimal number.
Try the following code:
public static byte[] decode(String hex){
String[] list=hex.split("(?<=\\G.{2})");
ByteBuffer buffer= ByteBuffer.allocate(list.length);
System.out.println(list.length);
for(String str: list)
buffer.put(Byte.parseByte(str,16));
return buffer.array();
}
To convert to String just create a new String with the byte[] returned by the decode method.
Just another way to convert hex string to java string:
public static String unHex(String arg) {
String str = "";
for(int i=0;i<arg.length();i+=2)
{
String s = arg.substring(i, (i + 2));
int decimal = Integer.parseInt(s, 16);
str = str + (char) decimal;
}
return str;
}
There is yet another way to do this if using JDK17 or above, see the new HexFormat class which has useful methods for converting byte[] <=> hexadecimal String :
String hexStr ="5468697320697320616e206578616d706c6520737472696e67";
byte[] bytes = HexFormat.of().parseHex(hexStr);
String str = new String(bytes, StandardCharsets.UTF_8 /* or Charset.forName("whateverencoding")*/);
You of course need to know the exact character encoding of the hexadecimal representation in order to generate the correct String value.
