前端实现微信公众平台分享

微信公众平台SDK开发文档地址

点击JSSDK跳转到相应的说明文档

1.png

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一般来说，wx.config里的需要用到的必填项时间戳、签名随机串、签名等等都是通过请求从后端获取的，前端直接拿到使用就可以了。但是现在遇到一个需求，要通过前端来实现这个呢？

debug

true / false 开启调试模式,调用的所有api的返回值会在客户端alert出来，若要查看传入的参数，可以在pc端打开，参数信息会通过log打出，仅在pc端时才会打印。

appId

公众号的唯一标识。

timestamp

生成签名的时间戳

var timestamp=new Date().getTime();

jsApiList

使用的JS接口列表，如：

jsApiList: [
                "onMenuShareTimeline",
                "onMenuShareAppMessage"
            ]

signature, nonceStr

签名和签名随机字符串。根据文档的说明，现获取access_token，再根据access_token获取jsapi_ticket，用拿到的jsapi_ticket根据签名算法算出签名。

签名生成规则如下：
参与签名的字段包括noncestr（随机字符串）, 有效的jsapi_ticket, timestamp（时间戳）, url（当前网页的URL，不包含#及其后面部分） 。对所有待签名参数按照字段名的ASCII 码从小到大排序（字典序）后，使用URL键值对的格式（即key1=value1&key2=value2…）拼接成字符串string1。这里需要注意的是所有参数名均为小写字符。对string1作sha1加密，字段名和字段值都采用原始值，不进行URL 转义。

//获取access_token
        $.get("https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=公众号的appid&secret=公众号的AppSecret",function (data) {
            console.log("data",data);
        },'jsonp');

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$.get("https://api.weixin.qq.com/cgi-bin/ticket/getticket?access_token=上个步骤拿到的access_token",function (data) {
            console.log("data",data);
        },'jsonp');

4.png

        var url=location.href;
        url=url.indexOf('#') >= 0 ? url.Substring(0, url.indexOf('#')) : url;
        var strings="jsapi_ticket="+jsapi_ticket+"&noncestr="+_strs+"×tamp="+timestamp+"&url="+url;

        var sha=hex_sha1(strings);//调用js sha1.js
        //随机字符
    var strs = ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'];
        // 创建随机字符串
    function CreatenNonce_str() {
            var sb="";
            var length = strs.length;
            for (var i = 0; i < length; i++) {
                var r = Math.random()*length;
                r=Math.ceil(r);
                sb+=strs[r-1];
            }
            return sb;
        }
        var _strs=CreatenNonce_str();

wx.config({
            debug: false,
            appId: '公众号appid',
            timestamp: timestamp, 
            nonceStr:_strs, 
            signature: sha,
            jsApiList: [
                "onMenuShareTimeline",
                "onMenuShareAppMessage"
            ]
        });

5.png

下面就可以直接按照文档开始调用各个接口了。

sha1加密的实现

/*
 * A JavaScript implementation of the Secure Hash Algorithm, SHA-1, as defined
 * in FIPS PUB 180-1
 * Version 2.1-BETA Copyright Paul Johnston 2000 - 2002.
 * Other contributors: Greg Holt, Andrew Kepert, Ydnar, Lostinet
 * Distributed under the BSD License
 * See http://pajhome.org.uk/crypt/md5 for details.
 */
/*
 * Configurable variables. You may need to tweak these to be compatible with
 * the server-side, but the defaults work in most cases.
 */
var hexcase = 0; /* hex output format. 0 - lowercase; 1 - uppercase     */
var b64pad = ""; /* base-64 pad character. "=" for strict RFC compliance  */
var chrsz = 8; /* bits per input character. 8 - ASCII; 16 - Unicode    */
/*
 * These are the functions you'll usually want to call
 * They take string arguments and return either hex or base-64 encoded strings
 */
function hex_sha1(s) {
 return binb2hex(core_sha1(str2binb(s), s.length * chrsz));
}
function b64_sha1(s) {
 return binb2b64(core_sha1(str2binb(s), s.length * chrsz));
}
function str_sha1(s) {
 return binb2str(core_sha1(str2binb(s), s.length * chrsz));
}
function hex_hmac_sha1(key, data) {
 return binb2hex(core_hmac_sha1(key, data));
}
function b64_hmac_sha1(key, data) {
 return binb2b64(core_hmac_sha1(key, data));
}
function str_hmac_sha1(key, data) {
 return binb2str(core_hmac_sha1(key, data));
}
/*
 * Perform a simple self-test to see if the VM is working
 */
function sha1_vm_test() {
 return hex_sha1("abc") == "a9993e364706816aba3e25717850c26c9cd0d89d";
}
/*
 * Calculate the SHA-1 of an array of big-endian words, and a bit length
 */
function core_sha1(x, len) {
 /* append padding */
 x[len >> 5] |= 0x80 << (24 - len % 32);
 x[((len + 64 >> 9) << 4) + 15] = len;
 var w = Array(80);
 var a = 1732584193;
 var b = -271733879;
 var c = -1732584194;
 var d = 271733878;
 var e = -1009589776;
 for (var i = 0; i < x.length; i += 16) {
  var olda = a;
  var oldb = b;
  var oldc = c;
  var oldd = d;
  var olde = e;
  for (var j = 0; j < 80; j++) {
   if (j < 16) w[j] = x[i + j];
   else w[j] = rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1);
   var t = safe_add(safe_add(rol(a, 5), sha1_ft(j, b, c, d)), safe_add(safe_add(e, w[j]), sha1_kt(j)));
   e = d;
   d = c;
   c = rol(b, 30);
   b = a;
   a = t;
  }
  a = safe_add(a, olda);
  b = safe_add(b, oldb);
  c = safe_add(c, oldc);
  d = safe_add(d, oldd);
  e = safe_add(e, olde);
 }
 return Array(a, b, c, d, e);
}
/*
 * Perform the appropriate triplet combination function for the current
 * iteration
 */
function sha1_ft(t, b, c, d) {
 if (t < 20) return (b & c) | ((~b) & d);
 if (t < 40) return b ^ c ^ d;
 if (t < 60) return (b & c) | (b & d) | (c & d);
 return b ^ c ^ d;
}
/*
 * Determine the appropriate additive constant for the current iteration
 */
function sha1_kt(t) {
 return (t < 20) ? 1518500249 : (t < 40) ? 1859775393 : (t < 60) ? -1894007588 : -899497514;
}
/*
 * Calculate the HMAC-SHA1 of a key and some data
 */
function core_hmac_sha1(key, data) {
 var bkey = str2binb(key);
 if (bkey.length > 16) bkey = core_sha1(bkey, key.length * chrsz);
 var ipad = Array(16),
  opad = Array(16);
 for (var i = 0; i < 16; i++) {
  ipad[i] = bkey[i] ^ 0x36363636;
  opad[i] = bkey[i] ^ 0x5C5C5C5C;
 }
 var hash = core_sha1(ipad.concat(str2binb(data)), 512 + data.length * chrsz);
 return core_sha1(opad.concat(hash), 512 + 160);
}
/*
 * Add integers, wrapping at 2^32. This uses 16-bit operations internally
 * to work around bugs in some JS interpreters.
 */
function safe_add(x, y) {
 var lsw = (x & 0xFFFF) + (y & 0xFFFF);
 var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
 return (msw << 16) | (lsw & 0xFFFF);
}
/*
 * Bitwise rotate a 32-bit number to the left.
 */
function rol(num, cnt) {
 return (num << cnt) | (num >>> (32 - cnt));
}
/*
 * Convert an 8-bit or 16-bit string to an array of big-endian words
 * In 8-bit function, characters >255 have their hi-byte silently ignored.
 */
function str2binb(str) {
 var bin = Array();
 var mask = (1 << chrsz) - 1;
 for (var i = 0; i < str.length * chrsz; i += chrsz)
 bin[i >> 5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - i % 32);
 return bin;
}
/*
 * Convert an array of big-endian words to a string
 */
function binb2str(bin) {
 var str = "";
 var mask = (1 << chrsz) - 1;
 for (var i = 0; i < bin.length * 32; i += chrsz)
 str += String.fromCharCode((bin[i >> 5] >>> (24 - i % 32)) & mask);
 return str;
}
/*
 * Convert an array of big-endian words to a hex string.
 */
function binb2hex(binarray) {
 var hex_tab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef";
 var str = "";
 for (var i = 0; i < binarray.length * 4; i++) {
  str += hex_tab.charAt((binarray[i >> 2] >> ((3 - i % 4) * 8 + 4)) & 0xF) + hex_tab.charAt((binarray[i >> 2] >> ((3 - i % 4) * 8)) & 0xF);
 }
 return str;
}
/*
 * Convert an array of big-endian words to a base-64 string
 */
function binb2b64(binarray) {
 var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 var str = "";
 for (var i = 0; i < binarray.length * 4; i += 3) {
  var triplet = (((binarray[i >> 2] >> 8 * (3 - i % 4)) & 0xFF) << 16) | (((binarray[i + 1 >> 2] >> 8 * (3 - (i + 1) % 4)) & 0xFF) << 8) | ((binarray[i + 2 >> 2] >> 8 * (3 - (i + 2) % 4)) & 0xFF);
  for (var j = 0; j < 4; j++) {
   if (i * 8 + j * 6 > binarray.length * 32) str += b64pad;
   else str += tab.charAt((triplet >> 6 * (3 - j)) & 0x3F);
  }
 }
 return str;
}

以上参考了
https://blog.csdn.net/u014805029/article/details/51382858
https://www.jianshu.com/p/cf3d09e35e55

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