在网站根目录下新建js目录，放入以下2个文件

js/jssdk.php
js/share.js

jssdk.php 代码如下

    <?php

    $url = $_GET['url'];//2017-06-27

    class JSSDK {
      private $appId;
      private $appSecret;
      private $url;//2017-06-27

      public function __construct($appId, $appSecret,$url) {
        $this->appId = $appId;
        $this->appSecret = $appSecret;
        $this->url = $url;//2017-06-27
      }

      public function getSignPackage() {
        $jsapiTicket = $this->getJsApiTicket();

        // 注意 URL 一定要动态获取，不能 hardcode.
        $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || 
        $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://";
        //$url = "$protocol$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";//2017-06-27
        $url =$this->url;//2017-06-27
       
        $timestamp = time();
        $nonceStr = $this->createNonceStr();

        // 这里参数的顺序要按照 key 值 ASCII 码升序排序
        $string = "jsapi_ticket=$jsapiTicket&noncestr=$nonceStr&timestamp=$timestamp&url=$url";

        $signature = sha1($string);

        $signPackage = array(
          "appId"     => $this->appId,
          "nonceStr"  => $nonceStr,
          "timestamp" => $timestamp,
          "url"       => $url,
          "signature" => $signature,
          "rawString" => $string
        );
        return $signPackage;
      }

      private function createNonceStr($length = 16) {
        $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        $str = "";
        for ($i = 0; $i < $length; $i++) {
          $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
        }
        return $str;
      }

      private function getJsApiTicket() {
        // jsapi_ticket 应该全局存储与更新，以下代码以写入到文件中做示例
        $data = json_decode(file_get_contents("jsapi_ticket.json"));
        if ($data->expire_time < time()) {
          $accessToken = $this->getAccessToken();
          // 如果是企业号用以下 URL 获取 ticket
          // $url = "https://qyapi.weixin.qq.com/cgi-bin/get_jsapi_ticket?access_token=$accessToken";
          $url = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?type=jsapi&access_token=$accessToken";
          $res = json_decode($this->httpGet($url));
          $ticket = $res->ticket;
          if ($ticket) {
            $data->expire_time = time() + 7000;
            $data->jsapi_ticket = $ticket;
            $fp = fopen("jsapi_ticket.json", "w");
            fwrite($fp, json_encode($data));
            fclose($fp);
          }
        } else {
          $ticket = $data->jsapi_ticket;
        }

        return $ticket;
      }

      private function getAccessToken() {
        // access_token 应该全局存储与更新，以下代码以写入到文件中做示例
        $data = json_decode(file_get_contents("access_token.json"));
        if ($data->expire_time < time()) {
          // 如果是企业号用以下URL获取access_token
          // $url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=$this->appId&corpsecret=$this->appSecret";
          $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=$this->appId&secret=$this->appSecret";
          $res = json_decode($this->httpGet($url));
          $access_token = $res->access_token;
          if ($access_token) {
            $data->expire_time = time() + 7000;
            $data->access_token = $access_token;
            $fp = fopen("access_token.json", "w");
            fwrite($fp, json_encode($data));
            fclose($fp);
          }
        } else {
          $access_token = $data->access_token;
        }
        return $access_token;
      }

      private function httpGet($url) {
        $curl = curl_init();
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($curl, CURLOPT_TIMEOUT, 500);
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, true);
        curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, true); //https
        curl_setopt($curl, CURLOPT_URL, $url);

        $res = curl_exec($curl);
        curl_close($curl);

        return $res;
      }
    }
    $jssdk = new JSSDK("AAPID", "appSecret",$url);
    $signPackage = $jssdk->GetSignPackage();
    $tmp=json_encode(array ('appId'=>$signPackage["appId"],'timestamp'=>$signPackage["timestamp"],
    'nonceStr'=>$signPackage["nonceStr"],'signature'=>$signPackage["signature"],'url'=>$signPackage["url"]));
    $callback = $_GET['callback'];
    echo $callback.'('.$tmp.')';
    exit;
    ?>

share.js代码如下

url = location.href;
$.ajax({
    type: "get",
    url: "../js/jssdk.php?url=" + url,
    dataType: "jsonp",
    jsonp: "callback",
    jsonpCallback: "success_jsonpCallback",
    success: function(data) {
        wx.config({
            appId: data.appId,
            timestamp: data.timestamp,
            nonceStr: data.nonceStr,
            signature: data.signature,
            jsApiList: ['chackJsApi', 'onMenuShareTimeline', 'onMenuShareAppMessage',
             'onMenuShareQQ', 'onMenuShareWeibo', 'onMenuShareQZone']
        });
    },
    error: function(data) {
        alert("连接失败！");
    }
});
wx.ready(function() {
    var shareData = {

        title: title,
        desc: desc,
        link: url,
        imgUrl: img,
        success: function(res) {
            //分享成功
        },
        cancel: function(res) {
            alert('已取消分享');
        }
    };
    wx.onMenuShareAppMessage(shareData);
    wx.onMenuShareTimeline(shareData);
    wx.onMenuShareQQ(shareData);
    wx.onMenuShareWeibo(shareData);
    wx.onMenuShareQZone(shareData);
});

部署方式 页面底部添加如下代码

<script src="https://res.wx.qq.com/open/js/jweixin-1.0.0.js"></script>
<script src="https://你的域名/js/share.js"></script>
<script>
var url = '你的域名';//用户要分享的网址
var title  = '您的标题';//分享的标题
var img = '您的图片地址';//分享的图片
var desc = '您的描述信息';//分享的描述信息
</script>