标签： JavaScript

JavaScript开发指南

关于编程生成MD5字符串的说明

一、在C#中生成MD5字符串：

// 要生成MD5的字符串
string text = "MD5";
// 获取字符串对应字符集的字节缓存数组
byte[] buffer = Encoding.UTF8.GetBytes(text);
// 创建MD5构造器
MD5 md5 = MD5.Create();
// 生成MD5字节缓存数组
buffer = md5.ComputeHash(buffer);
// 将MD5字节缓存数组构造成MD5字符串
StringBuilder stringBuilder = new StringBuilder();
foreach (byte item in buffer)
{
    stringBuilder.Append(item.ToString("x2"));
}
// 获取MD5字符串
return stringBuilder.ToString();

二、在Java中生成MD5字符串：

// 要生成MD5的字符串
String text = "MD5";
// 获取字符串对应字符集的字节缓存数组
byte[] buffer = text.getBytes("UTF-8");
// 创建MD5构造器
MessageDigest messageDigest = MessageDigest.getInstance("MD5");
messageDigest.reset();
// 生成MD5字节缓存数组
messageDigest.update(buffer);
buffer = messageDigest.digest();
// 将MD5字节缓存数组构造成MD5字符串
StringBuffer md5Buffer = new StringBuffer();
for (int i = 0, length = buffer.length; i < length; i++) {
    if (Integer.toHexString(0xFF & buffer[i]).length() == 1) {
        md5Buffer.append("0").append(Integer.toHexString(0xFF & buffer[i]));
    } else {
        md5Buffer.append(Integer.toHexString(0xFF & buffer[i]));
    }
}
// 获取MD5字符串
return md5Buffer.toString();

三、在PHP中生成MD5字符串：

// 要生成MD5的字符串
$text = 'MD5';
// 获取MD5字符串
return md5($text);

四、在JavaScript中生成MD5字符串：

// 定义MD5构造器
(function (window, undefined) {
    // 判断MD5构造器是否已经定义
    if (typeof (window.md5) == "function") {
        return;
    }
    // 定义MD5构造器相关function
    function safe_add(x, y) {
        var lsw = (x & 0xFFFF) + (y & 0xFFFF), msw = (x >> 16) + (y >> 16) + (lsw >> 16);
        return (msw << 16) | (lsw & 0xFFFF);
    }
    function bit_rol(num, cnt) {
        return (num << cnt) | (num >>> (32 - cnt));
    }
    function md5_cmn(q, a, b, x, s, t) {
        return safe_add(bit_rol(safe_add(safe_add(a, q), safe_add(x, t)), s), b);
    }
    function md5_ff(a, b, c, d, x, s, t) {
        return md5_cmn((b & c) | ((~b) & d), a, b, x, s, t);
    }
    function md5_gg(a, b, c, d, x, s, t) {
        return md5_cmn((b & d) | (c & (~d)), a, b, x, s, t);
    }
    function md5_hh(a, b, c, d, x, s, t) {
        return md5_cmn(b ^ c ^ d, a, b, x, s, t);
    }
    function md5_ii(a, b, c, d, x, s, t) {
        return md5_cmn(c ^ (b | (~d)), a, b, x, s, t);
    }
    function binl_md5(x, len) {
        x[len >> 5] |= 0x80 << (len % 32);
        x[(((len + 64) >>> 9) << 4) + 14] = len;
        var i, olda, oldb, oldc, oldd, a = 1732584193, b = -271733879, c = -1732584194, d = 271733878;
        for (i = 0; i < x.length; i += 16) {
            olda = a;
            oldb = b;
            oldc = c;
            oldd = d;
            a = md5_ff(a, b, c, d, x[i], 7, -680876936);
            d = md5_ff(d, a, b, c, x[i + 1], 12, -389564586);
            c = md5_ff(c, d, a, b, x[i + 2], 17, 606105819);
            b = md5_ff(b, c, d, a, x[i + 3], 22, -1044525330);
            a = md5_ff(a, b, c, d, x[i + 4], 7, -176418897);
            d = md5_ff(d, a, b, c, x[i + 5], 12, 1200080426);
            c = md5_ff(c, d, a, b, x[i + 6], 17, -1473231341);
            b = md5_ff(b, c, d, a, x[i + 7], 22, -45705983);
            a = md5_ff(a, b, c, d, x[i + 8], 7, 1770035416);
            d = md5_ff(d, a, b, c, x[i + 9], 12, -1958414417);
            c = md5_ff(c, d, a, b, x[i + 10], 17, -42063);
            b = md5_ff(b, c, d, a, x[i + 11], 22, -1990404162);
            a = md5_ff(a, b, c, d, x[i + 12], 7, 1804603682);
            d = md5_ff(d, a, b, c, x[i + 13], 12, -40341101);
            c = md5_ff(c, d, a, b, x[i + 14], 17, -1502002290);
            b = md5_ff(b, c, d, a, x[i + 15], 22, 1236535329);
            a = md5_gg(a, b, c, d, x[i + 1], 5, -165796510);
            d = md5_gg(d, a, b, c, x[i + 6], 9, -1069501632);
            c = md5_gg(c, d, a, b, x[i + 11], 14, 643717713);
            b = md5_gg(b, c, d, a, x[i], 20, -373897302);
            a = md5_gg(a, b, c, d, x[i + 5], 5, -701558691);
            d = md5_gg(d, a, b, c, x[i + 10], 9, 38016083);
            c = md5_gg(c, d, a, b, x[i + 15], 14, -660478335);
            b = md5_gg(b, c, d, a, x[i + 4], 20, -405537848);
            a = md5_gg(a, b, c, d, x[i + 9], 5, 568446438);
            d = md5_gg(d, a, b, c, x[i + 14], 9, -1019803690);
            c = md5_gg(c, d, a, b, x[i + 3], 14, -187363961);
            b = md5_gg(b, c, d, a, x[i + 8], 20, 1163531501);
            a = md5_gg(a, b, c, d, x[i + 13], 5, -1444681467);
            d = md5_gg(d, a, b, c, x[i + 2], 9, -51403784);
            c = md5_gg(c, d, a, b, x[i + 7], 14, 1735328473);
            b = md5_gg(b, c, d, a, x[i + 12], 20, -1926607734);
            a = md5_hh(a, b, c, d, x[i + 5], 4, -378558);
            d = md5_hh(d, a, b, c, x[i + 8], 11, -2022574463);
            c = md5_hh(c, d, a, b, x[i + 11], 16, 1839030562);
            b = md5_hh(b, c, d, a, x[i + 14], 23, -35309556);
            a = md5_hh(a, b, c, d, x[i + 1], 4, -1530992060);
            d = md5_hh(d, a, b, c, x[i + 4], 11, 1272893353);
            c = md5_hh(c, d, a, b, x[i + 7], 16, -155497632);
            b = md5_hh(b, c, d, a, x[i + 10], 23, -1094730640);
            a = md5_hh(a, b, c, d, x[i + 13], 4, 681279174);
            d = md5_hh(d, a, b, c, x[i], 11, -358537222);
            c = md5_hh(c, d, a, b, x[i + 3], 16, -722521979);
            b = md5_hh(b, c, d, a, x[i + 6], 23, 76029189);
            a = md5_hh(a, b, c, d, x[i + 9], 4, -640364487);
            d = md5_hh(d, a, b, c, x[i + 12], 11, -421815835);
            c = md5_hh(c, d, a, b, x[i + 15], 16, 530742520);
            b = md5_hh(b, c, d, a, x[i + 2], 23, -995338651);
            a = md5_ii(a, b, c, d, x[i], 6, -198630844);
            d = md5_ii(d, a, b, c, x[i + 7], 10, 1126891415);
            c = md5_ii(c, d, a, b, x[i + 14], 15, -1416354905);
            b = md5_ii(b, c, d, a, x[i + 5], 21, -57434055);
            a = md5_ii(a, b, c, d, x[i + 12], 6, 1700485571);
            d = md5_ii(d, a, b, c, x[i + 3], 10, -1894986606);
            c = md5_ii(c, d, a, b, x[i + 10], 15, -1051523);
            b = md5_ii(b, c, d, a, x[i + 1], 21, -2054922799);
            a = md5_ii(a, b, c, d, x[i + 8], 6, 1873313359);
            d = md5_ii(d, a, b, c, x[i + 15], 10, -30611744);
            c = md5_ii(c, d, a, b, x[i + 6], 15, -1560198380);
            b = md5_ii(b, c, d, a, x[i + 13], 21, 1309151649);
            a = md5_ii(a, b, c, d, x[i + 4], 6, -145523070);
            d = md5_ii(d, a, b, c, x[i + 11], 10, -1120210379);
            c = md5_ii(c, d, a, b, x[i + 2], 15, 718787259);
            b = md5_ii(b, c, d, a, x[i + 9], 21, -343485551);
            a = safe_add(a, olda);
            b = safe_add(b, oldb);
            c = safe_add(c, oldc);
            d = safe_add(d, oldd);
        }
        return [a, b, c, d];
    }
    function binl2rstr(input) {
        var i, output = '';
        for (i = 0; i < input.length * 32; i += 8) {
            output += String.fromCharCode((input[i >> 5] >>> (i % 32)) & 0xFF);
        }
        return output;
    }
    function rstr2binl(input) {
        var i, output = [];
        output[(input.length >> 2) - 1] = undefined;
        for (i = 0; i < output.length; i += 1) {
            output[i] = 0;
        }
        for (i = 0; i < input.length * 8; i += 8) {
            output[i >> 5] |= (input.charCodeAt(i / 8) & 0xFF) << (i % 32);
        }
        return output;
    }
    function rstr_md5(s) {
        return binl2rstr(binl_md5(rstr2binl(s), s.length * 8));
    }
    function rstr_hmac_md5(key, data) {
        var i, bkey = rstr2binl(key), ipad = [], opad = [], hash;
        ipad[15] = opad[15] = undefined;
        if (bkey.length > 16) {
            bkey = binl_md5(bkey, key.length * 8);
        }
        for (i = 0; i < 16; i += 1) {
            ipad[i] = bkey[i] ^ 0x36363636;
            opad[i] = bkey[i] ^ 0x5C5C5C5C;
        }
        hash = binl_md5(ipad.concat(rstr2binl(data)), 512 + data.length * 8);
        return binl2rstr(binl_md5(opad.concat(hash), 512 + 128));
    }
    function rstr2hex(input) {
        var hex_tab = '0123456789abcdef', output = '', x, i;
        for (i = 0; i < input.length; i += 1) {
            x = input.charCodeAt(i);
            output += hex_tab.charAt((x >>> 4) & 0x0F) + hex_tab.charAt(x & 0x0F);
        }
        return output;
    }
    function str2rstr_utf8(input) {
        return unescape(encodeURIComponent(input));
    }
    function raw_md5(s) {
        return rstr_md5(str2rstr_utf8(s));
    }
    function hex_md5(s) {
        return rstr2hex(raw_md5(s));
    }
    function raw_hmac_md5(k, d) {
        return rstr_hmac_md5(str2rstr_utf8(k), str2rstr_utf8(d));
    }
    function hex_hmac_md5(k, d) {
        return rstr2hex(raw_hmac_md5(k, d));
    }
    /**
    * text：要生成MD5的字符串
    * return：返回生成的MD5字符串
    */
    window.md5 = function (text, key, raw) {
        if (!key) {
            if (!raw) {
                return hex_md5(text);
            }
            return raw_md5(text);
        }
        if (!raw) {
            return hex_hmac_md5(key, text);
        }
        return raw_hmac_md5(key, text);
    };
})(window);

// 要生成MD5的字符串
var text = "MD5";
// 获取MD5字符串
return md5(text);

更多信息请参阅：MD5_百度百科

关于JavaScript中实现单链继承的说明

在实际开发中，我们常常会使用类的继承：子类既能继承父类的成员，又能重写和扩展父类的成员。而JavaScript是一种弱类型的直译式脚本语言，它没有类的概念，它的对象也是无法直接进行继承的。
但是我们知道在JavaScript中可以使用function和prototype来模拟类的实现，所以我们也可以用它们来实现基本的单链继承：

// 定义单链继承构造器
(function (window, undefined) {
    // 判断单链继承构造器是否已经定义
    if (typeof (window.inherit) == "function") {
        return;
    }
    /**
    * parentClass：父类function
    * subClass：子类function
    * subMembers：子类需要重写和扩展父类成员的对象
    */
    window.inherit = function (parentClass, subClass, subMembers) {
        // 原型链prototype继承
        var fun = function () { };
        fun.prototype = parentClass.prototype;
        subClass.prototype = new fun();
        subClass.prototype.constructor = subClass;
        subClass.prototype.parentObject = parentClass.prototype;
        if (parentClass.prototype.constructor == Object.prototype.constructor) {
            parentClass.prototype.constructor = parentClass;
        }
        // 子类重写和扩展父类成员
        if (subMembers) {
            for (var key in subMembers) {
                var value = subMembers[key];
                if (typeof (value) != "undefined") {
                    subClass.prototype[key] = subMembers[key];
                }
            }
        }
    };
})(window);

通过上述方法实现单链继承时，我们还需要在定义的子类function中使用JavaScript中的apply或call方法来显式地调用父类的function，从而达到回调父类构造函数的作用。

下面我们通过定义父类ParentClass和子类SubClass并调用inherit方法对上述原型链法单链继承进行验证：

// 定义父类ParentClass的function
var ParentClass = function () { };
// 通过prototype定义ParentClass的成员对象
ParentClass.prototype.a = function () {
    alert("ParentClass.a");
};
ParentClass.prototype.b = function () {
    alert("ParentClass.b");
};

// 定义子类SubClass的function
var SubClass = function () {
    // 显式调用父类ParentClass的function
    ParentClass.apply(this, arguments);
};
// 定义子类需要重写和扩展父类的成员对象
var subMembers = {
    // 重写父类ParentClass.b方法
    b: function () {
        alert("SubClass.b");
    },
    // 扩展子类SubClass.c方法
    c: function () {
        alert("SubClass.c");
    }
};

// 构造单链继承，将SubClass继承于ParentClass
inherit(ParentClass, SubClass, subMembers);

// 创建子类对象
var subClass = new SubClass();
// 验证继承结果
subClass.a(); // 结果：ParentClass.a
subClass.b(); // 结果：SubClass.b
subClass.c(); // 结果：SubClass.c
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