An analysis of HTTP message header Web page cache control and header common instruction introduction

This article is the HTTP Header page cache control and header commonly used instructions for a detailed analysis of the introduction, the need for friends to reference the  

The caching of the Web page is controlled by the "Cache-control" in the HTTP message header, and the common values are private, No-cache, Max-age, Must-revalidate, and so on, and the default is private. Its role is divided into the following situations according to different browsing methods:
(1) Open a new window
value is private, No-cache, Must-revalidate, then the server will be accessed when a new window is opened.
And if the Max-age value is specified, the server will not be accessed again in the time within this value, for example:
cache-control:max-age=5 (means to access the server again within 5 seconds of accessing this page)
(2) When the Address bar carriage return
value is private or must-revalidate, the server is accessed only for the first visit and is no longer accessible. The
value is No-cache and is accessed every time. The
value is Max-age, and no access is repeated until it expires.
(3) Press back button
to Private, must-revalidate, Max-age, no access,
value No-cache, repeat access every time
(4) Press the refresh button
to access this page does not leave a page backup on the Internet temporary article folder, regardless of the value, which will repeatedly access the
Cache-control value is "No-cache".
Additionally, caching is affected by specifying a "Expires" value. For example, to specify that the Expires value is a long past time, if you repeatedly press ENTER in the Address bar when you visit the network, you will repeat the visit each time: Expires:fri, Dec 1999 16:00:00 GMT
For example: Prohibit the page in IE cache
Strong>http Response message Header setting:
CacheControl = No-cache
Pragma=no-cache
Expires =-1
Expires is a good thing, if the Web page on the server often changes, set it to-1, indicating immediate expiration. If a page is updated daily 1 o'clock in the morning, you can set the expires to 1 o'clock in the morning the next day.
When the HTTP1.1 server specifies CacheControl = No-cache, the browser does not cache the Web page.
Legacy HTTP 1.0 Servers cannot use Cache-control headers.
Therefore, for backward compatibility with HTTP 1.0 servers, IE uses the Pragma:no-cache header to provide special support for HTTP.
Internet Explorer does not cache this response if the client communicates through a secure connection (https://)/with the server, and the server returns Pragma:no-cache headers in the response.
Note: Pragma:no-cache only prevents caching when used in a secure connection, and if used in an unsecured page, the processing is the same as expires:-1, and the page is cached but marked as immediately expired. The

Header common Directive
header is divided into three parts:
The first part is the HTTP protocol version (http-version);
The second part is state code (status);
Part III is divided into causal phrases (reason-phrase).

Copy Code code as follows:

//fix 404 Pages: Use this header directive to resolve the 404 header generated by the URL rewrite


header (' http/1.1 OK ');





//Set 404 Header: Page not found


header (' http/1.1 404 Not Found ');





//Page Permanent Redirect, you can tell the search engine to update their URLs


//Set Moved Permanently header (good for redrictions)


//Use with location header


header (' http/1.1 moved Permanently ');





//Access Limited


header (' http/1.1 403 Forbidden ');





//Server error


header (' http/1.1 Internal Server Error ');





//Redirect to a new location


//Redirect to a new location:


header (' location:http://www.www.jb51.net);





redirect
after a period of delay

//Redrict with delay:


header (' refresh:10; Url=http://www.jb51.net ');


print ' You'll be redirected in seconds ';





//Cover x-powered-by value


//override x-powered-by:php:


header (' x-powered-by:php/4.4.0 ');


header (' x-powered-by:brain/0.6b ');





//Content language (en = 中文版)


//Content language (en = 中文版)


header (' content-language:en ');





//Last modified (available at cache time)


//Last modified (good for caching)


$time = time ()-60; or Filemtime ($FN), etc


header (' last-modified: '. Gmdate (' d, D M Y h:i:s ', $time). ' GMT ');





//Tell the browser what to get is not yet updated


//header for telling the browser the content


//did not get changed


header (' http/1.1 304 not Modified ');





//Set the length of the content (available when cached):


//Set content length (good for caching):


header (' content-length:1234 ');





//used to download files:


//Headers for a download:


header (' Content-type:application/octet-stream ');


header (' content-disposition:attachment; filename= "Example.zip");


header (' content-transfer-encoding:binary ');





//Disable caching of current document:


//Load the file to Send:readfile (' example.zip ');


//Disable caching of the current document:


header (' Cache-control:no-cache, No-store, max-age=0, Must-revalidate ');


header (' Expires:mon, 1997 05:00:00 GMT ');





//Set Content type:


//Date in the Pastheader (' Pragma:no-cache ');


//Set Content type:


header (' content-type:text/html; charset=iso-8859-1 ');


header (' content-type:text/html; Charset=utf-8 ');


//Plain text file


header (' Content-type:text/plain ');





JPG Picture


header (' content-type:image/jpeg ');





//ZIP file


header (' Content-type:application/zip ');





//PDF file


header (' content-type:application/pdf ');





//Audio MPEG (MP3,...) file


header (' content-type:audio/mpeg ');





//Flash animation//show sign In box


header (' Content-type:application/x-shockwave-flash ');





//Display Login dialog box, which can be used for HTTP authentication


header (' http/1.1 401 Unauthorized ');


header (' Www-authenticate:basic realm= ' top Secret ');


print ' Text that'll be displayed if the user hits cancel or ';


print ' enters wrong login data ';