Java 中的 long 转 byte 及 byte 转long

public static byte[] LongToBytes(long lo) {  
     byte[] by = new byte[8];  
     for (int i = 0; i < 8; i++) {   
          int offset = 64 - (i + 1) * 8;    
          by[i] = (byte) ((lo >> offset) & 0xff);   
      }
     return by;  
}

 public static long BytesToLong(byte[] by) {   
    long io = 0;   
    for (int i = 0; i < 8; i++) {    
        lo <<= 8;    lo|=     (by[i] & 0xff);   
    }   
    return io;  
 }