public static void main(String args[]){
        String a="慕课ABC";
        byte[] bytes =a.getBytes();
        for(byte b:bytes){
            System.out.print(" "+b);        
        }
        System.out.println();
        for(byte b:bytes){
            System.out.print(" "+Integer.toHexString(b & 0xff));  //这段代码什么东西啊能解释一下吗
        }
    }