char c[] = "大家好".toCharArray();
        for(int i = 0;i<c.length;i++) {
        	c[i] = (char)(c[i] ^ 'Q');//將明文轉換成密文
        }
        String string = new String(c, 0, c.length);
        System.out.println("密文：" + string);
        for(int i=0;i<c.length;i++) {
        	c[i] = (char)(c[i] ^ 'Q');//將密文還原為明文
        }
        String string1 = new String(c, 0, c.length);
        System.out.println("明文：" + "\n" + string1);