我正在优化一个网站，并且通过谷歌的PageSpeed Insights工具得知我需要启用缓存。因此，我在我的.htaccess文件中添加了以下内容：
<IfModule mod_expires.c>
ExpiresActive On
ExpiresDefault "access 7 days"
ExpiresByType application/javascript "access plus 1 year"
ExpiresByType text/javascript "access plus 1 year"
ExpiresByType text/css "access plus 1 year"
ExpiresByType text/html "access plus 7 day"
ExpiresByType text/x-javascript "access 1 year"
ExpiresByType image/gif "access plus 1 year"
ExpiresByType image/jpeg "access plus 1 year"
ExpiresByType image/png "access plus 1 year"
ExpiresByType image/jpg "access plus 1 year"
ExpiresByType image/x-icon "access 1 year"
ExpiresByType application/x-shockwave-flash "access 1 year"
</IfModule>
<IfModule mod_headers.c>
<filesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gif|swf)$">
Header set Cache-Control "max-age=2592000, public"
</filesMatch>
<filesMatch "\.(css|js)$">
Header set Cache-Control "max-age=2592000, public"
</filesMatch>
<filesMatch "\.(xml|txt)$">
Header set Cache-Control "max-age=172800, public, must-revalidate"
</filesMatch>
<filesMatch "\.(html|htm|php)$">
Header set Cache-Control "max-age=172800, private, must-revalidate"
</filesMatch>
</IfModule>
<IfModule mod_setenvif.c>
BrowserMatch "MSIE" force-no-vary
BrowserMatch "Mozilla/4.[0-9]{2}" force-no-vary
</IfModule>
但这并没有帮助，我检查了phpinfo()加载的模块：
core itk http_core mod_so mod_auth_basic mod_auth_digest mod_authn_file mod_authn_alias mod_authn_anon mod_authn_dbm mod_authn_default mod_authz_host mod_authz_user mod_authz_owner mod_authz_groupfile mod_authz_dbm mod_authz_default util_ldap mod_authnz_ldap mod_include mod_log_config mod_logio mod_env mod_ext_filter mod_mime_magic mod_expires mod_deflate mod_headers mod_usertrack mod_setenvif mod_mime mod_dav mod_status mod_autoindex mod_info mod_dav_fs mod_vhost_alias mod_negotiation mod_dir mod_actions mod_speling mod_userdir mod_alias mod_substitute mod_rewrite mod_proxy mod_proxy_balancer mod_proxy_ftp mod_proxy_http mod_proxy_ajp mod_proxy_connect mod_cache mod_suexec mod_disk_cache mod_cgi mod_version mod_php5 mod_ispmgr
一切都没问题，但是它不起作用。有什么想法吗？