if(!empty($postStr)){
    
   //解析post来的XML为一个对象$postObj
   $postObj = simplexml_load_string($postStr, 'SimpleXMLElement', LIBXML_NOCDATA);
  
   $fromUsername = $postObj->FromUserName; //请求消息的用户
   $toUsername = $postObj->ToUserName; //"我"的公众号id
   $keyword = trim($postObj->Content); //用户发送的消息内容
   $time = time(); //时间戳
   $msgtype = 'text'; //消息类型：文本
   $textTpl = "<xml>
      <ToUserName><![CDATA[%s]]></ToUserName>
      <FromUserName><![CDATA[%s]]></FromUserName>
      <CreateTime>%s</CreateTime>
      <MsgType><![CDATA[%s]]></MsgType>
      <Content><![CDATA[%s]]></Content>
      </xml>";

elseif($which == "文章"){
    $ch = curl_init();
    $url = 'http://apis.baidu.com/showapi_open_bus/weixin/weixin_article_type';
    $header = array('apikey: 你自己的apikey');

    // 添加apikey到header
    curl_setopt($ch, CURLOPT_HTTPHEADER , $header);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    // 执行HTTP请求
    curl_setopt($ch , CURLOPT_URL , $url);
    $res = curl_exec($ch);
    $res = json_decode($res, true); //获取文章分类name和id

    foreach($res['showapi_res_body']['typeList'] as $v){
     $article[] = $v['id'] . "、" . $v['name'];
    }
    sort($article, SORT_NUMERIC);
    foreach($article as $v){
     $contentStr .= $v . "\n";
    }
    $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time, $msgtype, $contentStr);
    echo $resultStr;
    exit();


   }

elseif($which == "wz"){
    list($art_id, $page_id, $keyname) = split('，', $keyword);
    $art_id = str_replace('wz', '', $art_id);

    $ch = curl_init();
    $url = 'http://apis.baidu.com/showapi_open_bus/weixin/weixin_article_list?typeId=' . $art_id . '&page=' . $page_id . '&key=' . urlencode($keyname);

    $header = array('apikey: 你自己的apikey');

    // 添加apikey到header
    curl_setopt($ch, CURLOPT_HTTPHEADER , $header);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    // 执行HTTP请求
    curl_setopt($ch , CURLOPT_URL , $url);
    $res = curl_exec($ch);
    $res = json_decode($res, true);

    foreach($res['showapi_res_body']['pagebean']['contentlist'] as $k=>$v){
     if($k <= 6){
      $arts[] = $v;
     }else{
      break;
     }
    }

    $items = "";
    foreach($arts as $v){
     $items .= "<item>
    <Title><![CDATA[" . $v['title'] . "]]></Title> 
    <Description><![CDATA[" . $v['title'] . "]]></Description>
    <PicUrl><![CDATA[" . $v["contentImg"] . "]]></PicUrl>
    <Url><![CDATA[" . $v['url'] . "]]></Url>
    </item>";
    }



    $textTpl = "<xml>
    <ToUserName><![CDATA[%s]]></ToUserName>
    <FromUserName><![CDATA[%s]]></FromUserName>
    <CreateTime>%s</CreateTime>
    <MsgType><![CDATA[news]]></MsgType>
    <ArticleCount>7</ArticleCount>
    <Articles>" . $items . "
    </Articles>
    </xml> ";

    $resultStr = sprintf($textTpl, $fromUsername, $toUsername, $time);
    echo $resultStr;
    exit();


   }