在SAE上使用wx_sample.php获取token失败问题

“Talk is cheap， show me the code.”——Linus

<?php
header("Content-Type:text/html; charset=utf-8"); //添加这行
define("TOKEN", "weixin");
$wechatObj = new wechatCallbackapiTest();
$wechatObj->valid();

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

//valid signature , option
if($this->checkSignature())
{
header('content-type:text');//再添加这行
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 "";
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;
}
}
}

?>