第十九次总结 编码与解码[数据编码]

   String msg = "qwe123";
        //先得到消息摘要的对象 [加密方式对象]
        MessageDigest md = MessageDigest.getInstance("md5");
        //将要加密的字符串加入到消息摘要中
        md.update(msg.getBytes("utf-8"));
        //进行摘要加密，得到的是一个字节数组
        byte[] bs = md.digest();

        //将字节数组转换成大整数
        //BigInteger是一个任意精度的整数
        BigInteger num = new BigInteger(1,bs);
        //将整数转换成16进制的字符串
        String str = num.toString(16);
        System.out.println(str);



        MessageDigest md2 = MessageDigest.getInstance("sha-1");
        md2.update(msg.getBytes("utf-8"));
        byte[] bs2 = md2.digest();

        BigInteger num2 = new BigInteger(1,bs2);
        String str2 = num2.toString(16);
        System.out.println(str2);


        MessageDigest md3 = MessageDigest.getInstance("sha-256");
        md3.update(msg.getBytes("utf-8"));
        byte[] bs3 = md3.digest();

        String msg = "中文";
        //得到编码对象
        Base64.Encoder encoder = Base64.getEncoder();
        //开始编码
        byte[] bs = encoder.encode(msg.getBytes("utf-8"));

//        String str = encoder.encodeToString(msg.getBytes("UTF-8"));

        //得到编码之后的字符串
        String str = new String(bs,"UTF-8");
        System.out.println(str);

 //解码
        //得到解码器对象
        Base64.Decoder decoder = Base64.getDecoder();
        //解码，得到解码之后的字节数组
        byte[] bs2 = decoder.decode(str);

        String msg2 = new String(bs2,"UTF-8");
        System.out.println(msg2);


        //使用Base64对url中的中文进行处理
        String name="张三";
        Base64.Encoder urlEncoder = Base64.getUrlEncoder();
        String str3 = urlEncoder.encodeToString(name.getBytes("utf-8"));
        String url = "http://www.baidu.com?name="+str3+"&age=20";

        System.out.println(url);