define("TOKEN", "w3note");//定义识别码
$wechatObj = new wechatCallbackapiTest();//实例化wechatCallbackapiTest类
 
if(!isset($_GET["echostr"])){
     $wechatObj->responseMsg();
}else{
 $wechatObj->valid();
}
class wechatCallbackapiTest
{
 public function valid()
    {
        $echoStr = $_GET["echostr"];
        if($this->checkSignature()){
         echo $echoStr;
         exit;
        }
    }
    public function responseMsg()//执行接收器方法
    {
    $postStr = $GLOBALS["HTTP_RAW_POST_DATA"];
    if (!emptyempty($postStr)){
      $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
      $RX_TYPE = trim($postObj->MsgType);
      switch($RX_TYPE){
       case "event":
       $result = $this->receiveEvent($postObj);
       breadk;
      }
      echo $result;
  }else{
   echo "";
   exit;
  }
 }
  private function receiveEvent($object){
   $content = "";
   switch ($postObj->Event){
    case "subscribe":
    $content = "欢迎关注网志博客";//这里是向关注者发送的提示信息
    break;
    case "unsubscribe":
    $content = "";
    break;
   }
   $result = $this->transmitText($object,$content);
   return $result;
    }
 private function transmitText($object,$content){
   $textTpl = "<xml>
       <ToUserName><![CDATA[%s]]></ToUserName>
       <FromUserName><![CDATA[%s]]></FromUserName>
       <CreateTime>%s</CreateTime>
       <MsgType><![CDATA[text]]></MsgType>
       <Content><![CDATA[%s]]></Content>
       <FuncFlag>0</FuncFlag>
       </xml>";
    $result = sprintf($textTpl, $object->FromUserName, $object->$ToUserName, time(), $content);
    return $result;
  }
 private function checkSignature()
 {
  $signature = $_GET["signature"];
  $timestamp = $_GET["timestamp"];
  $nonce = $_GET["nonce"];
  $token = TOKEN;
  $tmpArr = array($token, $timestamp, $nonce);
  sort($tmpArr, SORT_STRING);
  $tmpStr = implode( $tmpArr );
  $tmpStr = sha1( $tmpStr );
  if( $tmpStr == $signature ){
   return true;
  }else{
   return false;
  }
 }
}