Brief analysis of HTTP header page cache control and header common Instruction _php tutorial

Source: Internet
Author: User
Tags http authentication
The cache 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, etc., and the default is private. Its function is divided into the following situations according to different ways of re-browsing:
(1) Open a new window
The value is private, No-cache, Must-revalidate, and the server will be re-accessed when a new window is opened.
If you specify a max-age value, the server is not re-accessed in the time within this value, for example:
Cache-control:max-age=5 (indicates that access will not go to the server within 5 seconds of accessing this page)
(2) Enter in the Address bar
A value of private or must-revalidate will only access the server on the first visit and will no longer be accessed at a later time.
The value is No-cache, which is accessed every time.
A value of max-age, the access is not repeated until it expires.
(3) Press Back button
The value is private, must-revalidate, Max-age, and is not re-accessed.
A value of No-cache, which is repeatedly accessed every time
(4) Press the Refresh button
No matter what the value, it will be accessed repeatedly
When the Cache-control value is "No-cache", accessing this page does not leave a page backup in the Temporary Internet Article folder.
Also, the cache is affected by specifying a value of "Expires". For example, specifying the Expires value is a time long past, then when you visit this network repeatedly press ENTER in the Address bar, then each time will be repeated access: Expires:fri, Dec 1999 16:00:00 GMT
For example: Prevent pages from being cached in IE
HTTP Response message header settings:
CacheControl = No-cache
Expires =-1
Expires is a good thing, if the Web page on the server changes frequently, it is set to 1, indicating immediate expiration. If a webpage is updated daily 1 o'clock in the morning, you can set 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 page.
Legacy HTTP 1.0 Servers cannot use the Cache-control header.
So for backwards compatibility with HTTP 1.0 servers, IE uses the Pragma:no-cache header to provide special support for HTTP.
If the client communicates with the server through a secure connection (https://), and the server returns the Pragma:no-cache header in the response,
Internet Explorer does not cache this response. Note: Pragma:no-cache prevents caching only when used in a secure connection, and if used in a non-secure page, is processed in the same way as expires:-1, the page is cached but is marked for immediate expiration.

Header Common Directives
The header is divided into three parts:
The first part is the version of the HTTP Protocol (http-version);
The second part is state code (status);
The third part is the reason phrase (reason-phrase).
Copy CodeThe code is as follows:
Fix 404 Pages: Use this header command to resolve the 404 header generated by URL rewriting
Header (' http/1.1 OK ');

Set 404 Header: Page not found
Header (' http/1.1 404 Not Found ');

Page permanent redirection, you can tell the search engine to update their URLs
Set Moved permanently header (Good for redrictions)
Use with location header
Header (' http/1.1 301 Moved permanently ');

Restricted access
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: ');

Redirect after a period of delay
Redrict with delay:
Header (' refresh:10; Url= ');
print ' You'll be redirected in ten seconds ';

Overwrite 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 time (can be used when caching)
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 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 (can be used when caching):
Set content Length (good for caching):
Header (' content-length:1234 ');

To download files:
Headers for an download:
Header (' Content-type:application/octet-stream ');
Header (' content-disposition:attachment; filename= ' ');
Header (' content-transfer-encoding:binary ');

Disable caching of the current document:
Load the file to Send:readfile (' ');
Disable caching of the current document:
Header (' Cache-control:no-cache, No-store, max-age=0, Must-revalidate ');
Header (' Expires:mon, Jul 1997 05:00:00 GMT ');

To set the 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 ');

Displays the 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 would be displayed if the user hits cancel or ';
print ' enters wrong login data '; true techarticle The cache 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, etc., and the default is private. Its effect depends on different ...

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