The PHP header method uses

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
Pragma=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).
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 ');

Pages are permanently deleted and 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:http://www.m-bang.com ');

Redirect after a period of delay
Redrict with delay:
Header (' refresh:10; url=http://www.sina.com.cn ');
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= ' Example.zip ');
Header (' content-transfer-encoding:binary ');

Disable caching of the 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, 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 ');
Header (' Content-type:text/plain ');

Plain text file
Header (' Content-type:image/jpeg ');

JPG picture
Header (' Content-type:application/zip ');

ZIP file
Header (' content-type:application/pdf ');

PDF file
Header (' Content-type:audio/mpeg ');

Audio MPEG (MP3,...) file
Header (' Content-type:application/x-shockwave-flash ');

Displays the Login dialog box, which can be used for HTTP authentication
Flash animation//show Sign In box
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 ';
?>
Now fill out the form, we can use Ajax to the user at any time to verify, friendly hints, but in the user did not pay attention to the Ajax friendly prompts, submitted the wrong form, jumped back to the original page, and fill in the information is all lost. To support page bounce, you have the following options:
1. Using the Session_cache_limiter method: Session_cache_limiter (' private,must-revalidate '); It should be noted, however, that the Session_cache_limiter () method is only useful before the Session_Start () method is written.
2. Use the header to set the control cache method: Header (' cache-control:private,must-revalidate ');

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