第一个公众微信demo老是运行不成功

我找了很多代码了，差不多都是如下代码：

valid();$wechatObj->responseMsg();class wechatCallbackapiTest{    public function valid()    {        $echoStr = $_GET["echostr"];        if($this->checkSignature()){            echo $echoStr;            exit;        }    }    public function responseMsg()    {        $postStr = $GLOBALS["HTTP_RAW_POST_DATA"];        if (!empty($postStr)){            $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);            $fromUsername = $postObj->FromUserName;            $toUsername = $postObj->ToUserName;            $keyword = trim($postObj->Content);            $time = time();            $textTpl = "                                    %s                                    0            ";            if(!empty( $keyword ))            {                $msgType = "text";                $contentStr = '你好啊，?丝';                $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgType, $contentStr);                echo $resultStr;            }else{                echo '咋不说哈呢';            }        }else {            echo '咋不说哈呢';            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;        }    }}?>

回复讨论(解决方案)

我的服务器是自己买的阿里云vps主机 php的运行环境

哥们，帮我看看这个问题吧http://bbs.csdn.net/topics/390946850

去我的博客看看吧

微信回复都是要已xml格式返回，怎么判断条件中还有直接echo的。

去我的博客看看吧