session_set_save_handler
(PHP 4 , PHP 5)
session_set_save_handler --
Sets user-level session storage functions
Description
bool
session_set_save_handler ( string open, string close, string read, string write, string destroy, string gc)
session_set_save_handler() sets the user-level
session storage functions which are used for storing and
retrieving data associated with a session. This is most useful
when a storage method other than those supplied by PHP sessions
is preferred. i.e. Storing the session data in a local database.
如果成功则返回 TRUE，失败则返回 FALSE。
注:
The "write" handler is not executed until after the output
stream is closed. Thus, output from debugging statements in the
"write" handler will never be seen in the browser. If debugging
output is necessary, it is suggested that the debug output be
written to a file instead.
注:
The write handler is not executed if the session contains no data;
this applies even if empty session variables are registered. This
differs to the default file-based session save handler, which creates
empty session files.
The following example provides file based session
storage similar to the PHP sessions default save handler
files. This example could easily be
extended to cover database storage using your favorite PHP
supported database engine.
Read function must return string value always to make save
handler work as expected. Return empty string if there is no data
to read. Return values from other handlers are converted to
boolean expression. TRUE for success, FALSE for failure.
例子 1.
session_set_save_handler() example
<?php
function open($save_path, $session_name)
{
global $sess_save_path, $sess_session_name;
$sess_save_path = $save_path;
$sess_session_name = $session_name;
return(true);
}
function close()
{
return(true);
}
function read($id)
{
global $sess_save_path, $sess_session_name;
$sess_file = "$sess_save_path/sess_$id";
if ($fp = @fopen($sess_file, "r")) {
$sess_data = fread($fp, filesize($sess_file));
return($sess_data);
} else {
return(""); // Must return "" here.
}
}
function write($id, $sess_data)
{
global $sess_save_path, $sess_session_name;
$sess_file = "$sess_save_path/sess_$id";
if ($fp = @fopen($sess_file, "w")) {
return(fwrite($fp, $sess_data));
} else {
return(false);
}
}
function destroy($id)
{
global $sess_save_path, $sess_session_name;
$sess_file = "$sess_save_path/sess_$id";
return(@unlink($sess_file));
}
/*********************************************
* WARNING - You will need to implement some *
* sort of garbage collection routine here. *
*********************************************/
function gc($maxlifetime)
{
return true;
}
session_set_save_handler("open", "close", "read", "write", "destroy", "gc");
session_start();
// proceed to use sessions normally
?>
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See also the session.save_handler
configuration directive.