Java: byte[] Integer.toHexString()

 

 

 

 

 

 

 

 

 

byte[] => hexString

package io.oar;


import java.util.Formatter;

public class TestByteToHex{
  public static void main(String[] args){
    byte[] bytes = {-54, -2, -70, -66};

    byte b = -54;
    int i = b >>> 1;  // << >> >>> 都会转换成int

    System.out.println("byteToHex1(bytes) = " + byteToHex1(bytes));
    System.out.println("byteToHex2(bytes) = " + byteToHex2(bytes));
    System.out.println("byteToHex3(bytes) = " + byteToHex3(bytes));

  }

  public static String byteToHex1(byte[] bytes){
    char[] chars = "0123456789ABCDEF".toCharArray();
    char[] res = new char[bytes.length * 2];
    for(int i = 0; i < bytes.length; i++){
      int v = bytes[i] & 0xFF;  // byte => int
      res[2 * i] = chars[v >>> 4];  // byte的前四bits
      res[2 * i + 1] = chars[v & 0x0F];  // byte的后四bits
    }

    return new String(res);
  }

  public static String byteToHex2(byte[] bytes){
    StringBuilder stringBuilder = new StringBuilder();
    for(byte aByte : bytes){
      stringBuilder.append(String.format("%02X", aByte));
    }
    return stringBuilder.toString();
  }

  public static String byteToHex3(byte[] bytes){
    Formatter formatter = new Formatter();
    for(byte aByte : bytes){
      formatter.format("%02X", aByte);
    }
    String res = formatter.toString();
    formatter.close();
    return res;
  }
}