php代码

<?php
/**
* @author Seraphim
* @copyright 2012
*/
// 
function sendheader($last_modified, $p_type, $content_length = 0)
{
  // 设置客户端缓存有效时间
  header("Expires: " . gmdate("D, d M Y H:i:s", time() + 15360000) . "GMT");
  header("Cache-Control: max-age=315360000");
  header("Pragma: ");
  // 设置最后修改时间
  header("Last-Modified: " . $last_modified);
  // 设置文件类型信息
  header($p_type);
  header("Content-Length: " . $content_length);
}
define('ABSPATH', dirname(__file__) . '/');
$cache = true;
$cachedir = 'cache/'; //存放gz文件的目录，确保可写
if (empty($_SERVER['QUERY_STRING']))
  exit();
$gzip = strstr($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip');
if (empty($gzip))
  $cache = false;
$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'; //生成gz文件路径
$ext = array_pop(explode('.', $filename)); //根据后缀判断文件类型信息
$type = "Content-type: text/html"; //默认的文件类型
switch ($ext)
{
  case 'css':
    $type = "Content-type: text/css";
    break;
  case 'js':
    $type = "Content-type: text/javascript";
    break;
  case 'gif':
    $cache = false;
    $type = "Content-type: image/gif";
    break;
  case 'jpg':
    $cache = false;
    $type = "Content-type: image/jpeg";
    break;
  case 'png':
    $cache = false;
    $type = "Content-type: image/png";
    break;
  default:
    exit();
}
if ($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'])) ==
      $gmt_mtime))
    {
      // 与浏览器cache中的文件修改日期一致，返回304
      header("HTTP/1.1 304 Not Modified");
      // 发送客户端header
      header("Content-Encoding :gzip");
      sendheader($gmt_mtime, $type);
    }
    else
    {
      // 读取gz文件输出
      $content = file_get_contents($cache_filename);
      // 发送客户端header
      sendheader($gmt_mtime, $type, strlen($content));
      header("Content-Encoding: gzip");
      // 发送数据
      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';
      // 读取文件
      $content = file_get_contents($filename);
      // 去掉空白的部分
      // $content = ltrim($content);
      // 压缩文件内容
      $content = gzencode($content, 9, $gzip ? FORCE_GZIP : FORCE_DEFLATE);
      // 发送客户端header
      sendheader($gmt_mtime, $type, strlen($content));
      header("Content-Encoding: gzip");
      // 发送数据
      echo $content;
      // 写入文件
      file_put_contents($cache_filename, $content);
    }
    else
    {
      header("HTTP/1.0 404 Not Found");
    }
}
else
{ // 处理不使用Gzip模式下的输出。原理基本同上
  if (file_exists($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'])) ==
      $gmt_mtime))
    {
      // 与浏览器cache中的文件修改日期一致，返回304
      header("HTTP/1.1 304 Not Modified");
      // 发送客户端header
      sendheader($gmt_mtime, $type, strlen($content));
      header("Content-Encoding :gzip");
    }
    else
    {
      // 读取文件输出
      $content = file_get_contents($filename);
      // 发送客户端header
      sendheader($gmt_mtime, $type, strlen($content));
      // 发送数据
      echo $content;
    }
  }
  else
  {
    header("HTTP/1.0 404 Not Found");
  }
}
?>