字符串，int,十六进制相互转换

public class TypeConvert       {  
    /* 字符串转byte[] 
 这个方法转换后的结果是会多一些 48字符进来的就是代表的是0不知道为什么，但是可以只是取出指定的字符串
    */  
  public static byte[] hexStringToBytes(String hexString) 
     {  
       if (hexString == null || hexString.equals(""))
        {         
                 return null;  
   }  
    hexString = hexString.toUpperCase();  
    int length = hexString.length() / 2;  
    char[] hexChars = hexString.toCharArray();  
    byte[] d = new byte[length];  
    for (int i = 0; i < length; i++) {  
        int pos = i * 2;  
        d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1]));  
    }  
    return d;  
}  

    /* byte转short */  
    public final static short getShort(byte[] buf, boolean asc, int len) {  
        short r = 0;  
        if (asc)  
          for (int i = len - 1; i >= 0; i--) {  
            r <<= 8;  
            r |= (buf[i] & 0x00ff);  
          }  
        else  
          for (int i = 0; i < len; i++) {  
            r <<= 8;  
            r |= (buf[i] & 0x00ff);  
          }  

        return r;  
   }  

    /* B2 -> 0xB2 */  
    public static int stringToByte(String in, byte[] b) throws Exception {   
       if (b.length < in.length() / 2) {   
            throw new Exception("byte array too small");   
        }  

        int j=0;  
       StringBuffer buf = new StringBuffer(2);   
       for (int i=0; i<in.length(); i++, j++) {   
           buf.insert(0, in.charAt(i));   
            buf.insert(1, in.charAt(i+1));   
            int t = Integer.parseInt(buf.toString(),16);   
            System.out.println("byte hex value:" + t);   
            b[j] = (byte)t;  
            i++;   
            buf.delete(0,2);   
        }   

        return j;  
    }  

    /* byte to  int */  
   public final static int getInt(byte[] buf, boolean asc, int len) {  
        if (buf == null) {  
          throw new IllegalArgumentException("byte array is null!");  
       }  
        if (len > 4) {  
          throw new IllegalArgumentException("byte array size > 4 !");  
        }  
        int r = 0;  
        if (asc)  
          for (int i = len - 1; i >= 0; i--) {  
            r <<= 8;  
            r |= (buf[i] & 0x000000ff);  
          }  
        else  
          for (int i = 0; i < len; i++) {  
            r <<= 8;  
            r |= (buf[i] & 0x000000ff);  
          }  
       return r;  
    }  

   /* int -> byte[] */  
    public static byte[] intToBytes(int num) {  
       byte[] b = new byte[4];  
      for (int i = 0; i < 4; i++) {  
       b[i] = (byte) (num >>> (24 - i * 8));  
       }  

       return b;  
    }  

    /* short to byte[] */  
    public static byte[] shortToBytes(short num) {  
      byte[] b = new byte[2];  

      for (int i = 0; i < 2; i++) {  
           b[i] = (byte) (num >>> (i * 8));  
       }  

     return b;  
    }  

    /* byte to String */  
   private static char findHex(byte b) {   
        int t = new Byte(b).intValue();   
       t = t < 0 ? t + 16 : t;   

       if ((0 <= t) &&(t <= 9)) {   
       return (char)(t + '0');   
       }   

        return (char)(t-10+'A');   
    }   
    public static String byteToString(byte b) {   
        byte high, low;   
        byte maskHigh = (byte)0xf0;   
        byte maskLow = 0x0f;   

        high = (byte)((b & maskHigh) >> 4);   
        low = (byte)(b & maskLow);   

        StringBuffer buf = new StringBuffer();   
        buf.append(findHex(high));   
        buf.append(findHex(low));   

       return buf.toString();   
    }  

   /* short -> byte */  
    public final static byte[] getBytes(short s, boolean asc) {  
       byte[] buf = new byte[2];  
       if (asc)      for (int i = buf.length - 1; i >= 0; i--) {  buf[i] = (byte) (s & 0x00ff);  
           s >>= 8;  
          }  
       else  
         for (int i = 0; i < buf.length; i++) {  
          buf[i] = (byte) (s & 0x00ff);  
            s >>= 8;  
         }  
       return buf;  
     }  
    /* int -> byte[] */  
      public final static byte[] getBytes(int s, boolean asc) {  
        byte[] buf = new byte[4];  
       if (asc)  
          for (int i = buf.length - 1; i >= 0; i--) {  
            buf[i] = (byte) (s & 0x000000ff);  
           s >>= 8;  
         }  
       else  
        for (int i = 0; i < buf.length; i++) {  
            buf[i] = (byte) (s & 0x000000ff);  
            s >>= 8;  
          }  
        return buf;  
     }  

     /* long -> byte[] */  
      public final static byte[] getBytes(long s, boolean asc) {  
       byte[] buf = new byte[8];  
        if (asc)  
         for (int i = buf.length - 1; i >= 0; i--) {  
           buf[i] = (byte) (s & 0x00000000000000ff);  
            s >>= 8;  
          }  
        else  
          for (int i = 0; i < buf.length; i++) {  
            buf[i] = (byte) (s & 0x00000000000000ff);  
            s >>= 8;  
          }  
        return buf;  
     }  

      /* byte[]->int */  
      public final static int getInt(byte[] buf, boolean asc) {  
        if (buf == null) {  
         throw new IllegalArgumentException("byte array is null!");  
       }  
        if (buf.length > 4) {  
          throw new IllegalArgumentException("byte array size > 4 !");  
        }  
       int r = 0;  
        if (asc)  
          for (int i = buf.length - 1; i >= 0; i--) {  
            r <<= 8;  
           r |= (buf[i] & 0x000000ff);  
          }  
        else  
          for (int i = 0; i < buf.length; i++) {  
          r <<= 8;  
           r |= (buf[i] & 0x000000ff);  
          }  
        return r;  
     }  
     /* byte[] -> long */  
      public final static long getLong(byte[] buf, boolean asc) {  
        if (buf == null) {  
          throw new IllegalArgumentException("byte array is null!");  
       }  
        if (buf.length > 8) {  
         throw new IllegalArgumentException("byte array size > 8 !");  
        }  
        long r = 0;  
        if (asc)  
          for (int i = buf.length - 1; i >= 0; i--) {  
            r <<= 8;  
           r |= (buf[i] & 0x00000000000000ff);  
         }  
        else  
          for (int i = 0; i < buf.length; i++) {  
           r <<= 8;  
            r |= (buf[i] & 0x00000000000000ff);  
          }  
        return r;  
      }  
}