回答

<?php
/**
* 微信公众平台操作类
*/
class WeChat
{
    private $_appid;
    private $_appsecret;
    //微信公众平台请求开发者的服务器需要token
    private $_token;

    //标识qrcodeticket的类型，是永久还是临时
    const QRCODE_TYPE_TEMP = 1;
    const QRCODE_TYPE_TEMP_STR = 2;
    const QRCODE_TYPE_LIMIT = 3;
    const QRCODE_TYPE_LIMIT_STR = 4;

    /**
    * 构造函数
    * @param string $id     appid
    * @param string $secret app秘钥
    */
    public function __construct($id, $secret, $token) {
        $this->_appid = $id;
        $this->_appsecret = $secret;
        $this->_token = $token;
    }

    /**
    * 用于第一次验证URl合法性
    */
    public function firstValid() {
        //校验签名的合法性
        if ($this->_checkSignature()) {
            //签名合法，告知微信服务器
            echo $_GET['echostr'];
        }
    }
    /**
    * 验证签名
    * @return [type] [description]
    */
    private function _checkSignature() {
        //获取由微信服务器发过来的数据
        $signature = $_GET['signature'];
        $timestamp = $_GET['timestamp'];
        $nonce = $_GET['nonce'];
        //开始验证数据
        $tmp_arr = array($this->_token, $timestamp, $nonce);
        sort($tmp_arr, SORT_STRING);
        $tmp_str = implode($tmp_arr);
        $tmp_str = sha1($tmp_str);
        //对比数据
        if ($signature == $tmp_str) {
            return true;
        } else {
            return false;
        }
    }

    /**
    * 消息类型判断
    * @return array
    */
    public function responseMsg() {
        //因为很多都设置了register_globals禁止,不能用$GLOBALS["HTTP_RAW_POST_DATA"] 改用file_get_contents("php://input")即可
        $postStr = file_get_contents("php://input");
        if (!empty($postStr)) {
            $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
            $RX_TYPE = trim($postObj->MsgType);
            //用户发送的消息类型判断
            switch ($RX_TYPE) {
                case "text":    //文本消息
                    return array('type' => 'text', 'msg' => '文本', 'obj' => $postObj);
                    break;
                case "image":   //图片消息
                    return array('type' => 'image', 'msg' => '图片', 'obj' => $postObj);
                    break;

                case "voice":   //语音消息
                    return array('type' => 'voice', 'msg' => '语音', 'obj' => $postObj);
                    break;
                case "video":   //视频消息
                    return array('type' => 'video', 'msg' => '视频', 'obj' => $postObj);
                    break;
                case "location"://位置消息
                    return array('type' => 'location', 'msg' => '位置', 'obj' => $postObj);
                    break;
                case "link":    //链接消息
                    return array('type' => 'link', 'msg' => '链接', 'obj' => $postObj);
                    break;
                case "event":    //事件消息
                    return array('type' => 'event', 'msg' => $postObj->Event, 'obj' => $postObj);
                    break;
                default:
                    return array('type' => 'unknow msg type', 'msg' => '未知', 'obj' => $postObj);
                    break;
            }
        } else {
            echo "";
            exit;
        }
    }


    /**
    * 获取 access_tonken值
    * @param string $token_file 用来存储的文件
    * @return access_token
    */
    public function getAccessToken($token_file = 'access_token_file') {
        //处理是否过期问题，将access_token存储到文件
        $life_time = 7200;
        if (file_exists($token_file) && time() - filemtime($token_file) < $life_time) {
            // 存在有效的access_token 直接返回文件内容
            return file_get_contents($token_file);
        }
        //接口URL
        $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=".$this->_appid."&secret=".$this->_appsecret;
        //发送GET请求
        $result = $this->_request('get', $url);
        if (!$result) {
            return false;
        }
        //处理数据
        $result_obj = json_decode($result);
        //写入到文件
        file_put_contents($token_file, $result_obj->access_token);
        return $result_obj->access_token;
    }

    /**
    * 获取Ticket
    * @param string $content 二维码内容
    * @param int $type 二维码类型 1 临时整形 2临时字符串 3永久整形 4永久字符串
    * @param int $expire 有效时间
    * @return ticket
    */
    public function getQRCodeTicket($content, $type = 2, $expire = 604800) {
        $access_token = $this->getAccessToken();
        $url = 'https://api.weixin.qq.com/cgi-bin/qrcode/create?access_token='.$access_token;
        $type_list = array(
            self::QRCODE_TYPE_TEMP => 'QR_SCENE',
            self::QRCODE_TYPE_TEMP_STR => 'QR_STR_SCENE',
            self::QRCODE_TYPE_LIMIT => 'QR_LIMIT_SCENE',
            self::QRCODE_TYPE_LIMIT_STR => 'QR_LIMIT_STR_SCENE'
        );
        $action_name = $type_list[$type];
        //post发送的数据
        switch ($type) {
            case self::QRCODE_TYPE_TEMP:
                $data_arr['expire_seconds'] = $expire;
                $data_arr['action_name'] = $action_name;
                $data_arr['action_info']['scene']['scene_id'] = $content;
                break;
            case self::QRCODE_TYPE_TEMP_STR:
                $data_arr['expire_seconds'] = $expire;
                $data_arr['action_name'] = $action_name;
                $data_arr['action_info']['scene']['scene_str'] = $content;
                break;
            case self::QRCODE_TYPE_LIMIT:
                $data_arr['action_name'] = $action_name;
                $data_arr['action_info']['scene']['scene_id'] = $content;
                break;
            case self::QRCODE_TYPE_LIMIT_STR:
                $data_arr['action_name'] = $action_name;
                $data_arr['action_info']['scene']['scene_str'] = $content;
                break;
        }
        $data = json_encode($data_arr);
        $result = $this->_request('post', $url, $data);
        if (!$result) {
            return false;
        }
        $result_obj = json_decode($result);
        return $result_obj->ticket;
    }

    /**
    * 根据ticket获取二维码
    * @param int|string $content qrcode内容标识
    * @param [type] $file 存储为文件的地址，如果null直接输出
    * @param integer $type 类型
    * @param integer $expire 如果是临时，标识有效期
    * @return  [type]
    */
    public function getQRCode($content, $file = NULL, $type = 2, $expire = 604800) {
        //获取ticket
        $ticket = $this->getQRCodeTicket($content, $type = 2, $expire = 604800);
        $url = "https://mp.weixin.qq.com/cgi-bin/showqrcode?ticket=$ticket";
        //发送，取得图片数据
        $result = $this->_request('get', $url);
        if ($file) {
            file_put_contents($file, $result);
        } else {
            header('Content-Type:image/jpeg');
            echo $result;
        }
    }


    /**
    * 封装发送http请求
    * @param string $method 请求方式 get/post
    * @param string $url 请求目标的url
    * @param array $data post发送的数据
    * @param bool $ssl 是否为https协议
    * @return 响应主体
    */
    private function _request($method = 'get', $url, $data = array(), $ssl = true) {
        //curl完成，先开启curl模块
        //初始化一个curl资源
        $curl = curl_init();
        //设置curl选项
        curl_setopt($curl, CURLOPT_URL, $url); //url
        //请求的代理信息
        $user_agent = isset($_SERVER['HTTP_USER_AGENT'])?$_SERVER['HTTP_USER_AGENT']: 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0 FirePHP/0.7.4';
        curl_setopt($curl, CURLOPT_USERAGENT, $user_agent);
        //referer头，请求来源
        curl_setopt($curl, CURLOPT_AUTOREFERER, true);
        curl_setopt($curl, CURLOPT_TIMEOUT, 30); //设置超时时间
        //SSL相关
        if ($ssl) {
            //禁用后，curl将终止从服务端进行验证;
            curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
            //检查服务器SSL证书是否存在一个公用名
            curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, 2);
        }
        //判断请求方式post还是get
        if (strtolower($method) == 'post') {
            /**************处理post相关选项******************/
            //是否为post请求 ,处理请求数据
            curl_setopt($curl, CURLOPT_POST, true);
            curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
        }
        //是否处理响应头
        curl_setopt($curl, CURLOPT_HEADER, false);
        //是否返回响应结果
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);

        //发出请求
        $response = curl_exec($curl);
        if (false === $response) {
            echo '<br>',
            curl_error($curl),
            '<br>';
            return false;
        }
        //关闭curl
        curl_close($curl);
        return $response;
    }

}
header('Content-type:text/html;charset=utf8');


$appid = ""; //这里请填你真实的参数值
$appsecret = ""; //这里请填你真实的参数值
$token = ""; //这里请填你真实的参数值

$wx = new WeChat($appid, $appsecret, $token);

//验证url
$wx->firstValid();

//判断消息类型
$result = $wx->responseMsg();

if ($result['type'] == 'text') {
    //文本消息
    transmitText($result['obj'], '你发送的是文本，内容为：'.$result['obj']->Content);
}
if ($result['type'] == 'event') {
    //文本消息
    if ($result['msg'] == 'subscribe') {
        //如果是订阅事件
        $openid = $result['obj']->FromUserName; //openid
        $scene_id = str_replace("qrscene_", "", $result['obj']->EventKey);

        transmitText($result['obj'], '欢迎订阅'.$scene_id);
    }

    if ($result['msg'] == 'SCAN') {//r如果是已经关注过的
        //如果是订阅事件
        $openid = $result['obj']->FromUserName; //openid
        $scene_id = str_replace("qrscene_", "", $result['obj']->EventKey);

        transmitText($result['obj'], '欢迎订阅'.$scene_id);
    }

}



/*
 * 接收文本消息
 */
function receiveText($object) {
    $content = "你发送的是文本，内容为：".$object->Content;
    $result = $this->transmitText($object, $content);
    return $result;
}

/*
 * 回复文本消息
 */
function transmitText($object, $content) {
    $textTpl = "<xml>
        <ToUserName><![CDATA[%s]]></ToUserName>
        <FromUserName><![CDATA[%s]]></FromUserName>
        <CreateTime>%s</CreateTime>
        <MsgType><![CDATA[text]]></MsgType>
        <Content><![CDATA[%s]]></Content>
        </xml>";
    $result = sprintf($textTpl, $object->FromUserName, $object->ToUserName, time(), $content);
    //  file_put_contents('./test.txt', $result);
    echo $result; die;
    // return $result;
}