第一步：获取access token

access_token是公众号的全局唯一票据，公众号调用各接口时都需使用access_token。正常情况下access_token有效期为7200秒，重复获取将导致上次获取的access_token失效。

公众号可以使用AppID和AppSecret调用本接口来获取access_token。AppID和AppSecret可在开发模式中获得（需要已经成为开发者，且帐号没有异常状态）。注意调用所有微信接口时均需使用https协议。

接口调用说明

http请求方式: GET

https://api./cgi-bin/token?grant_type=client_credential&appid=APPID&secret=APPSECRET

参数说明

返回说明

正常情况下，微信会返回下述JSON数据包给公众号：

{“access_token”:“ACCESS_TOKEN”,“expires_in”:7200}

错误时微信会返回错误码等信息，JSON数据包示例如下（该示例为AppID无效错误）:

{“errcode”:40013,“errmsg”:“invalid appid”}

第二步：获取jsapi_ticket

生成签名之前必须先了解一下jsapi_ticket，jsapi_ticket是公众号用于调用微信JS接口的临时票据。正常情况下，jsapi_ticket的有效期为7200秒，通过access_token来获取。由于获取jsapi_ticket的api调用次数非常有限，频繁刷新jsapi_ticket会导致api调用受限，影响自身业务，开发者必须在自己的服务全局缓存jsapi_ticket 。

用第一步拿到的access_token 采用http GET方式请求获得jsapi_ticket（有效期7200秒，开发者必须在自己的服务全局缓存jsapi_ticket），接口地址如下

https://api./cgi-bin/ticket/getticket?access_token=ACCESS_TOKEN&type=jsapi

成功返回如下JSON：

{

“errcode”:0,

“errmsg”:“ok”,

“ticket”:“bxLdikRXVbTPdHSM05e5u5sUoXNKd8-41ZO3MhKoyN5OfkWITDGgnr2fwJ0m9E8NYzWKVZvdVtaUgWvsdshFKA”,

“expires_in”:7200

}

3. 签名算法实现

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。

即signature=sha1(string1)。示例：

noncestr=Wm3WZYTPz0wzccnW

jsapi_ticket=sM4AOVdWfPE4DxkXGEs8VMCPGGVi4C3VM0P37wVUCFvkVAy_90u5h9nbSlYy3-Sl-HhTdfl2fzFy1AOcHKP7qg

timestamp=1414587457

url=http://mp.?params=value

步骤1. 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：

jsapi_ticket=sM4AOVdWfPE4DxkXGEs8VMCPGGVi4C3VM0P37wVUCFvkVAy_90u5h9nbSlYy3-Sl-HhTdfl2fzFy1AOcHKP7qg&noncestr=Wm3WZYTPz0wzccnW&timestamp=1414587457&url=http://mp.?params=value

步骤2. 对string1进行sha1签名，得到signature：

0f9de62fce790f9a083d5c99e95740ceb90c27ed

示例

<?phpclass JSSDK {private $appId;private $appSecret;public function __construct($appId, $appSecret) {$this->appId = $appId;$this->appSecret = $appSecret;}public function getSignPackage() {$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]$_SERVER[REQUEST_URI]";$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// $url = "https://qyapi./cgi-bin/get_jsapi_ticket?access_token=$accessToken";$url = "https://api./cgi-bin/ticket/getticket?type=jsapi&access_token=$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// $url = "https://qyapi./cgi-bin/gettoken?corpid=$this->appId&corpsecret=$this->appSecret";$url = "https://api./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, false);curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, false);curl_setopt($curl, CURLOPT_URL, $url);$res = curl_exec($curl);curl_close($curl);return $res;}}