PHP教程
<?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)){
  /* libxml_disable_entity_loader is to prevent XML eXternal Entity Injection,
   the best way is to check the validity of xml by yourself */
  libxml_disable_entity_loader(true);
   $postObj = simplexml_load_string($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()
 {
 // you must define TOKEN by yourself
 if (!defined("TOKEN")) {
  throw new Exception('TOKEN is not defined!');
 }
 $signature = $_GET["signature"];
 $timestamp = $_GET["timestamp"];
 $nonce = $_GET["nonce"];
 $token = TOKEN;
 $tmpArr = array($token, $timestamp, $nonce);
 // use SORT_STRING rule
 sort($tmpArr, SORT_STRING);
 $tmpStr = implode( $tmpArr );
 $tmpStr = sha1( $tmpStr );
 if( $tmpStr == $signature ){
  return true;
 }else{
  return false;
 }
 }
}
?>

PHP教程
<?php
/**
 * wechat php test
 */
//define your token
define("TOKEN", "weixin");
$wechatObj = new wechatCallbackapiTest();
//這里做了更改
if($_GET["echostr"]){
 $wechatObj->valid();
}else{
 $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)){
  /* libxml_disable_entity_loader is to prevent XML eXternal Entity Injection,
   the best way is to check the validity of xml by yourself */
  libxml_disable_entity_loader(true);
   $postObj = simplexml_load_string($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()
 {
 // you must define TOKEN by yourself
 if (!defined("TOKEN")) {
  throw new Exception('TOKEN is not defined!');
 }
 $signature = $_GET["signature"];
 $timestamp = $_GET["timestamp"];
 $nonce = $_GET["nonce"];
 $token = TOKEN;
 $tmpArr = array($token, $timestamp, $nonce);
 // use SORT_STRING rule
 sort($tmpArr, SORT_STRING);
 $tmpStr = implode( $tmpArr );
 $tmpStr = sha1( $tmpStr );
 if( $tmpStr == $signature ){
  return true;
 }else{
  return false;
 }
 }
}
?>