<?php
/*
 http://fanyi.youdao.com/openapi.do?keyfrom=weifan&key=791593512&type=data&doctype=<doctype>&version=1.1&q=要翻译的文本 
    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();
            $textTpl = "<xml>
                        <ToUserName><![CDATA[%s]]></ToUserName>
                        <FromUserName><![CDATA[%s]]></FromUserName>
                        <CreateTime>%s</CreateTime>
                        <MsgType><![CDATA[%s]]></MsgType>
                        <Content><![CDATA[%s]]></Content>
                        <FuncFlag>0</FuncFlag>
                        </xml>";
            if(!empty($keyword))
            {
                $msgType = "text";
                $contentStr = "哈哈";
                $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgType, $contentStr);
                echo $resultStr;
            }elseif( $keyword == "A")
            {
                $msgType = "text";
                $contentStr = "OK";
                $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgType, $contentStr);
                echo $resultStr;
            }elseif( $keyword == "B")
            {
                $msgType = "text";
                $contentStr = "good";
                $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgType, $contentStr);
                echo $resultStr;
            }else if($keyword == "liudan"){
                $msgType = "text";
                $contentStr = "么么哒！！<font color = 'red'>".$keyword."</font>哈哈";
                $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgType, $contentStr);
                echo $resultStr;
exit();

        }
        }else{
            $msgType = "text";
                $contentStr = $keyword;
                $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgType, $contentStr);
                echo $resultStr;
            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;
        $log_filename = "weixinlog.xml";
        if(file_exists($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);
    }
}
?>

微信开发简单例子