System.out.print(Integer.toHexString(buf[i]) & 0xff+" ");
错误:The operator & is undefined for the argument type(s) java.lang.String, java.lang.String
System.out.print(Integer.toHexString(buf[i] & 0xff)+" ");括号
System.out.print(Integer.toHexString(buf[i] & 0xff ) + " ")
(buf[i] & 0xff) + " " 你括号搞错了