define("TOKEN", "w3note");//定義識別碼 
$wechatObj = new wechatCallbackapiTest();//實例化wechatCallbackapiTest類 
 
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()//執行接收器方法 
    { 
    $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 = "歡迎關注網志博客";//這里是向關注者發送的提示信息 
    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; 
  } 
 } 
}