微信公众平台接口

<?php
/**
  * wechat php test
  *///define your token
define("TOKEN", "qianshou");
$wechatObj = new wechatCallbackapiTest();
$wechatObj->valid();
$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();
                $textTpl = "<xml>
<ToUserName><![CDATA[%s]]></ToUserName>
<FromUserName><![CDATA[%s]]></FromUserName>
<CreateTime>%s</CreateTime>
<MsgType><![CDATA[%s]]></MsgType>
<Content><![CDATA[%s]]></Content>
<FuncFlag>0</FuncFlag>
</xml>";             
if(!empty( $keyword ))
                {
               $msgType = "text";
                 $contentStr = "Welcome to wechat world!";
                 $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgType, $contentStr);
                 echo $resultStr;
                }else{
                 echo "Input something...";
                }        }else {
         echo "qianshouerror";
         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;
}
}
}?>这个代码有什么问题吗？以下是技术文档的链接：http://mp.weixin.qq.com/wiki/index.php?title=%E9%A6%96%E9%A1%B5微信PHPapi