使用PHP和JavaScript判断请求是否来自微信内浏览器

mozilla/5.0 (iphone; cpu iphone os 5_1 like mac os x) applewebkit/534.46 (khtml, like gecko) mobile/9b176 micromessenger/4.3.2)

mozilla/5.0 (linux; u; android 2.3.6; zh-cn; gt-s5660 build/gingerbread) applewebkit/533.1 (khtml, like gecko) version/4.0 mobile safari/533.1 micromessenger/4.5.255)

if(strpos($_server["http_user_agent"],"micromessenger"))
  echo "welcome to wechat word";
else
  echo "http/1.1 401 unauthorized";

public function is_weixin(){ 
if ( strpos($_server['http_user_agent'], 'micromessenger') !== false ) {
 return true;
}
 return false;
}    
if($this->is_weixin()){
 }else{
 echo "请使用微信访问本网址。";
} 

function is_weixin(){
  var ua = navigator.useragent.tolowercase();
  if(ua.match(/micromessenger/i)=="micromessenger") {
    return true;
   } else {
    return false;
  }
}

<script type="text/javascript" src="/jslib/wx_share.js"></script>
    <script>
      //分享链接时给其重写分享的标题、缩略图、链接、简介等
      var imgurl = '<?php echo base_url('/images/per.png'); ?>';
      var linelink = 'http://www.baidu.com/';
      var sharetitle = '我来给你送钱了';
      var desccontent = '折射率，你知道是啥？';
      var timeline_title = 'timeline_title';
      var appid = '';
    </script>
    <script>
      function onbridgeready() {
        weixinjsbridge.call('showoptionmenu');
      }
    </script>
    <script>
      if (typeof weixinjsbridge == "undefined") {
        if (document.addeventlistener) {
          document.addeventlistener('weixinjsbridgeready', onbridgeready, false);
        } else if (document.attachevent) {
          document.attachevent('weixinjsbridgeready', onbridgeready);
          document.attachevent('onweixinjsbridgeready', onbridgeready);
        }
      } else {
        onbridgeready();
      }
    </script>
</head>