rand(1,10)

$tyep= $postObj->MsgType;
$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>";   

 if ($tyep=="image")
 {
  $a=rand(1,3);
   switch ($a)
   {
    case "1";
     $b="健康好人緣，婚姻幸福美滿";
     break;
   case "2";
     $b="貴人相助化險為夷的好運紋";
     break;
    default;
     $b="才華橫溢好研究，知識豐富事業有成";        
   }

   $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time,$b);
   echo $resultStr;
 }

?php
/**
 * wechat php test
 */

//define your token
define("TOKEN", "weixin");
$wechatObj = new wechatCallbackapiTest();
$wechatObj->responseMsg();

class wechatCallbackapiTest
{
 public function valid()
 {
  $echoStr = $_GET["echostr"];

  //valid signature , option
  if($this->checkSignature()){
   echo $echoStr;
   exit;
  }
 }

 public function responseMsg()
 {
  //get post data, May be due to the different environments
  $postStr = $GLOBALS["HTTP_RAW_POST_DATA"];

  //extract post data
  if (!empty($postStr)){

    $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
    $fromUsername = $postObj->FromUserName;
    $toUsername = $postObj->ToUserName;
    $keyword = trim($postObj->Content);
    $time = time();
    $tyep= $postObj->MsgType;
    $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>";   


    if ($tyep=="image")
    {$a=rand(1,3);
     switch ($a)
     {case "1";
     $b="健康好人緣，婚姻幸福美滿";
     break;
     case "2";
     $b="貴人相助化險為夷的好運紋";
     break;
     default;
     $b="才華橫溢好研究，知識豐富事業有成";        
     }

     $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time,$b);
     echo $resultStr;
    }

  }else {
   echo "";
   exit;
  }
 }

 private function checkSignature()
 {
  $signature = $_GET["signature"];
  $timestamp = $_GET["timestamp"];
  $nonce = $_GET["nonce"]; 

  $token = TOKEN;
  $tmpArr = array($token, $timestamp, $nonce);
  sort($tmpArr);
  $tmpStr = implode( $tmpArr );
  $tmpStr = sha1( $tmpStr );

  if( $tmpStr == $signature ){
   return true;
  }else{
   return false;
  }
 }
}

?>