public class Util {
 final static int LINE_COUNT = 16;
 final static int WORD_COUNT = 2;
 public static StringBuffer toHex(byte b)
 {
  byte factor = 16;
  int v = b & 0xff;//去掉byte轉換之后的負數部分。
  byte high = (byte)( v / factor);
  byte low = (byte)(v % factor);
  StringBuffer buf = new StringBuffer();
  buf.append(toHexLow(high)).append(toHexLow(low));
  return buf;
 }
 private static char toHexLow(byte b)
 {
  if(b > 16 || b < 0 )
  {
   throw new IllegalArgumentException("inpt parameter should less than 16 and greater than 0");
  }
  if(b < 10){
   return (char)('0' + (char)b);
  }
  else{
    return (char)('A' + (b-10));

  }
 }
 
 public static StringBuffer toHex(int val)
 {
  StringBuffer buf = toHex((byte)(val >>24 & 0xff)).append(toHex((byte)(val>>16&0xff)));
  return buf.append(toHex((byte)(val>>8&0xff))).append(toHex((byte)(val & 0xff)));
 }
 
 /**
  * 打印二進制數組
  * @param arr
  * @param off
  * @param len
  */
 public static void printBytes(byte [] arr,int off,int len)
 {
  if(arr == null || len <= 0 || off <0 || off + len > arr.length){
   return;
  }
  
  int count = 0;
  
  for(int i = off; count < len; ++i)
  {
   System.out.print(toHex(arr[i]));
   
   ++ count;
   if(count% WORD_COUNT == 0)
   {
    System.out.print(' ');
   }
   if(count % LINE_COUNT == 0)
   {
    System.out.println();
   }
  }
 }
 
 public static void main(String[] args) {
  byte[] arr = new byte[256];
  for(int i = 0; i < 256;++i )
  {
   
   arr[i] = (byte)i;
   
  }
  
  printBytes(arr,0,256);
  printBytes(arr,240,16);
  
  System.out.println(toHex(1));
  System.out.println(toHex(0xffffffff));
  System.out.println(toHex(0xeeffaacc));
 }
}

另外c++寫好的小端序的int數據，用java讀入如此處理
 private static int convertInt(byte[]  arr)
 {
  if(arr == null || arr.length != 4)
  {
   throw new IllegalArgumentException("bytes array error");
  }
  int val = (arr[0] & 0xff) | (arr[1] & 0xff)<<8 | (arr[2] & 0xff)<<16 | (arr[3]&0xff)<<24;
  return val;
 }