php新手求微信PHP的注释
<?php
/**
  * wechat php test
  */

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

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...";
                }

     &