浏览器检测类

 class   BrowserDetector
  {
      var   $UA   =   "";   //$HTTP_USER_AGENT的内容
      var   $BROWSER=   "Unknown";   //浏览器类型
      var   $PLATFORM   =   "Unknown";   //操作系统
      var   $VERSION=   "";   //浏览器版本号
      var   $MAJORVER   =   "";   //浏览器主版本号
      var   $MINORVER   =   "";   //浏览器副版本号
  /*   构造函数开始   */
      function   BrowserDetector()
      {
          $this->UA   =   getenv(HTTP_USER_AGENT);
          $preparens   =   "";
          $parens   =   "";
          $i   =   strpos($this->UA,"(");
          if   ($i   >=   0)
          {
              $preparens   =   trim(substr($this->UA,0,$i));
              $parens   =   substr($this->UA,$i+1,strlen($this->UA));
              $j   =   strpos($parens,")");
              if($j>=0)   {
              $parens   =   substr($parens,0,$j);
          }
      }
      else   {
      $preparens   =   $this->UA;
      }
      $browVer   =   $preparens;
      $token   =   trim(strtok($parens,";"));
      while($token)   {
      if($token=="compatible")   {
      }
      elseif(preg_match("/MSIE/i","$token"))   {
      $browVer   =   $token;
      }
      elseif(preg_match("/Opera/i","$token"))   {
      $browVer   =   $token;
      }
      elseif(preg_match("/X11/i","$token")   ||   preg_match("/SunOS/i","$token")   ||   preg_match   ("/Linux/i","$token"))   {
      $this->PLATFORM   =   "Unix";
      }
      elseif(preg_match("/Win/i","$token"))   {
      $this->PLATFORM   =   $token;
      }
      elseif(preg_match("/Mac/i","$token")   ||   preg_match("/PPC/i","$token"))   {
      $this->PLATFORM   =   $token;
      }
      $token   =   strtok(";");
      }
      $msieIndex   =   strpos($browVer,"MSIE");
      if($msieIndex   >=   0)   {
      $browVer   =   substr($browVer,$msieIndex,strlen($browVer));
      }
      $leftover   =   "";
      if(substr($browVer,0,strlen("Mozilla"))   ==   "Mozilla")   {
      $this->BROWSER   =   "Netscape";
      $leftover=substr($browVer,strlen("Mozilla")+1,strlen($browVer));
      }
      elseif(substr($browVer,0,strlen("Lynx"))   ==   "Lynx")   {
      $this->BROWSER   =   "Lynx";
      $leftover=substr($browVer,strlen("Lynx")+1,strlen($browVer));
      }
      elseif(substr($browVer,0,strlen("MSIE"))   ==   "MSIE")   {
      $this->BROWSER   =   "IE";
      $leftover=substr($browVer,strlen("MSIE")+1,strlen($browVer));
      }
      elseif(substr($browVer,0,strlen("Microsoft   Internet   Explorer"))   ==   "Microsoft   Internet   Explorer")   {
      $this->BROWSER   =   "IE";
      $leftover=substr($browVer,strlen("Microsoft   Internet   Explorer")+1,strlen($browVer));
      }
      elseif(substr($browVer,0,strlen("Opera"))   ==   "Opera")   {
      $this->BROWSER   =   "Opera";
      $leftover=substr($browVer,strlen("Opera")+1,strlen($browVer));
      }
      $leftover   =   trim($leftover);
      $i=strpos($leftover,"   ");
      if($i   >   0)   {
      $this->VERSION   =   substr($leftover,0,$i);
      }
      else   {
      $this->VERSION   =   $leftover;
      }
      $j   =   strpos($this->VERSION,".");
      if($j   >=   0)   {
      $this->MAJORVER   =   substr($this->VERSION,0,$j);
      $this->MINORVER   =   substr($this->VERSION,$j+1,strlen($this->VERSION));
      }
      else   {
      $this->MAJORVER   =   $this->VERSION;
      }
      }
  }