Token验证失败的解决方法

<?php
/*
方倍工作室 http://www.cnblogs.com/txw1958/ CopyRight 2013 www.doucube.com  All Rights Reserved
*/
traceHttp();

define("TOKEN", "weixin");
$wechatObj = new wechatCallbackapiTest();
if (isset($_GET['echostr'])) {
$wechatObj->valid();
}else{
$wechatObj->responseMsg();
}

class wechatCallbackapiTest
{
public function valid()
{
$echoStr = $_GET["echostr"];
if($this->checkSignature()){
echo $echoStr;
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;
}
}

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();
$textTpl = "<xml>
<ToUserName><![CDATA[%s]]></ToUserName>
<FromUserName><![CDATA[%s]]></FromUserName>
<CreateTime>%s</CreateTime>
<MsgType><![CDATA[%s]]></MsgType>
<Content><![CDATA[%s]]></Content>
<FuncFlag>0</FuncFlag>
</xml>";
if($keyword == "?" || $keyword == "？")
{
$msgType = "text";
$contentStr = date("Y-m-d H:i:s",time());
$resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgType, $contentStr);
echo $resultStr;
}
}else{
echo "";
exit;
}
}
}

function traceHttp()
{
logger("\n\nREMOTE_ADDR:".$_SERVER["REMOTE_ADDR"].(strstr($_SERVER["REMOTE_ADDR"],'101.226')? " FROM WeiXin": "Unknown IP"));
logger("QUERY_STRING:".$_SERVER["QUERY_STRING"]);
}
function logger($log_content)
{
if(isset($_SERVER['HTTP_APPNAME'])){   //SAE
sae_set_display_errors(false);
sae_debug($log_content);
sae_set_display_errors(true);
}else{ //LOCAL
$max_size = 500000;
$log_filename = "log.xml";
if(file_exists($log_filename) and (abs(filesize($log_filename)) > $max_size)){unlink($log_filename);}
file_put_contents($log_filename, date('Y-m-d H:i:s').$log_content."\r\n", FILE_APPEND);
}
}
?>