在php虚拟主机中启用gzip压缩的方法

define('ABSPATH', dirname(__FILE__).'/');
$cache = true;//Gzip压缩开关
$cachedir = 'gzip_cache/';//存放gz文件的目录，使用前创建，并赋予可写权限
$gzip = strstr($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip');
$deflate = strstr($_SERVER['HTTP_ACCEPT_ENCODING'], 'deflate');
$encoding = $gzip ? 'gzip' : ($deflate ? 'deflate' : 'none');
if(!isset($_SERVER['QUERY_STRING'])) exit();
$key=array_shift(explode('?', $_SERVER['QUERY_STRING']));
$key=str_replace('../','',$key);
$filename=ABSPATH.$key;
$symbol='^';
$rel_path=str_replace(ABSPATH,'',dirname($filename));
$namespace=str_replace('/',$symbol,$rel_path);
$cache_filename=ABSPATH.$cachedir.$namespace.$symbol.basename($filename).'.gz';//缓存路径
$type="Content-type: text/html"; //MIME信息
$ext = array_pop(explode('.', $filename));//获取文件扩展名
switch ($ext){//更新MIME信息
  case 'css':
   $type="Content-type: text/css";
   break;
  case 'js':
   $type="Content-type: text/javascript";
   break;
  default:
   exit();
}
if($cache){
 if(file_exists($cache_filename)){//假如存在gz文件

   $mtime = filemtime($cache_filename);
   $gmt_mtime = gmdate('D, d M Y H:i:s', $mtime) . ' GMT';

   if( (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) &&
         array_shift(explode(';', $_SERVER['HTTP_IF_MODIFIED_SINCE'])) ==  $gmt_mtime)
    ){

    // 若文件无变动，返回304
     header ("HTTP/1.1 304 Not Modified");
     header("Expires: ");
     header("Cache-Control: ");
     header("Pragma: ");
     header($type);
     header("Tips: Cache Not Modified (Gzip)");
     header ('Content-Length: 0');
   }else{
     //读取gz文件输出
     $content = file_get_contents($cache_filename);
     header("Last-Modified:" . $gmt_mtime);
     header("Expires: ");
     header("Cache-Control: ");
     header("Pragma: ");
     header($type);
     header("Tips: Normal Respond (Gzip)");
     header("Content-Encoding: gzip");
     echo $content;
   }
 }else if(file_exists($filename)){ //没有对应的gz文件
    $mtime = mktime();
    $gmt_mtime = gmdate('D, d M Y H:i:s', $mtime) . ' GMT';

    $content = file_get_contents($filename);
    $content = gzencode($content, 9, $gzip ? FORCE_GZIP : FORCE_DEFLATE);//压缩内容

    header("Last-Modified:" . $gmt_mtime);
    header("Expires: ");
    header("Cache-Control: ");
    header("Pragma: ");
    header($type);
    header("Tips: Build Gzip File (Gzip)");
    header ("Content-Encoding: " . $encoding);
          header ('Content-Length: ' . strlen($content));
    echo $content;
    if ($fp = fopen($cache_filename, 'w')) {//写入缓存
                fwrite($fp, $content);
                fclose($fp);
            }
 }else{
    header("HTTP/1.0 404 Not Found");
 }
}else{ //关闭Gzip压缩
//by bbs.it-home.org
 if(file_exists($filename)){
   $mtime = filemtime($filename);
   $gmt_mtime = gmdate('D, d M Y H:i:s', $mtime) . ' GMT';

   if( (isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) &&
   array_shift(explode(';', $_SERVER['HTTP_IF_MODIFIED_SINCE'])) ==  $gmt_mtime)
   ){

    header ("HTTP/1.1 304 Not Modified");
    header("Expires: ");
    header("Cache-Control: ");
    header("Pragma: ");
    header($type);
    header("Tips: Cache Not Modified");
    header ('Content-Length: 0');

   }else{

    header("Last-Modified:" . $gmt_mtime);
    header("Expires: ");
    header("Cache-Control: ");
    header("Pragma: ");
    header($type);
    header("Tips: Normal Respond");
    $content = readfile($filename);
    echo $content;

   }
 }else{
   header("HTTP/1.0 404 Not Found");
 }
}
?>

接着，在.htaccess(Apache mod_rewrite)或httpd.ini(IIS ISAPI_Rewrite)中添加以下规则：

RewriteRule (.*.css$|.*.js$) /gzip.php\?$1 [L]

最后，进行测试。 访问网站的各个页面，看看gzip_cache文件夹中是否有缓存文件生成。 也可以用百度站长工具，可以看到css/js页面是否压缩。