Session 函数
在线手册：中文 英文
PHP手册

session_name

(PHP 4, PHP 5)

session_name — Get and/or set the current session name

说明

string session_name ([ string $name ] )

session_name() returns the name of the current session. If name is given, session_name() will update the session name and return the old session name.

The session name is reset to the default value stored in session.name at request startup time. Thus, you need to call session_name() for every request (and before session_start() or session_register() are called).

参数

name

The session name references the name of the session, which is used in cookies and URLs (e.g. PHPSESSID). It should contain only alphanumeric characters; it should be short and descriptive (i.e. for users with enabled cookie warnings). If name is specified, the name of the current session is changed to its value.

Warning

The session name can't consist of digits only, at least one letter must be present. Otherwise a new session id is generated every time.

返回值

Returns the name of the current session.

范例

Example #1 session_name() example

<?php

/* set the session name to WebsiteID */

$previous_name = session_name("WebsiteID");

echo "The previous session name was $previous_name<br />";
?>

参见

Session 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: Get and/or set the current session name

用户评论:

Joseph Dalrymple (15-Apr-2011 07:52)

For those wondering, this function is expensive!

On a script that was executing in a consistent 0.0025 seconds, just the use of session_name("foo") shot my execution time up to ~0.09s. By simply sacrificing session_name("foo"), I sped my script up by roughly 0.09 seconds.

relsqui at chiliahedron dot com (21-Feb-2009 07:07)

Remember, kids--you MUST use session_name() first if you want to use session_set_cookie_params() to, say, change the session timeout. Otherwise it won't work, won't give any error, and nothing in the documentation (that I've seen, anyway) will explain why.

Thanks to brandan of bildungsroman.com who left a note under session_set_cookie_params() explaining this or I'd probably still be throwing my hands up about it.

php at wiz dot cx (28-Sep-2008 04:36)

if you try to name a php session "example.com" it gets converted to "example_com" and everything breaks.

don't use a period in your session name.

xemc at yahoo dot com (26-Aug-2008 09:20)

Here's a sample program I made to explore the operation of the session stuff.  One thing I wanted to do was switch sessions in the middle of a script - where session_name doesn't automatically create or resume the corresponding session id...  (anyone have a better idea?)

<?php
if ( $_REQUEST['sname'] ) {
    session_name($_REQUEST['sname']);
}
session_start();

$messages = "";
function show( $str ) {  global $messages;  $messages .= $str; }
function show_sess_vars() {
    foreach ( $_SESSION as $key => $val ) {
        show("Session var '$key': \t'$val'\n");
    }
}

show("Session name: \t" . session_name() . "\n");
show("Session ID: \t" . session_id() . "\n");
foreach ( $_REQUEST as $key => $val ) {
    if ( $key == 'regenerate' )
    {
        session_regenerate_id();
        show("session_regenerate_id();\n");
        show("Session name: \t" . session_name() . "\n");
        show("Session ID: \t" . session_id() . "\n");
    }
    else if ( $key == 'clear' )
    {
        $_SESSION = array();
        show("\$_SESSION = array();\n");
    }
    else if ( $key == 'switch' )
    {
        show("Will attempt to switch session name.. vars:\n");
        show_sess_vars();
        session_write_close();
        $res = session_name($val);
        show("session_name($val) - res: $res\n");
        session_start();
        show("Session name: \t" . session_name() . "\n");
        show("Session ID: \t" . session_id() . "\n");
    }
    else if ( $key == 'switch2' )
    {
        show("Will attempt to switch session name.. vars:\n");
        show_sess_vars();
        session_write_close();
        show("session_write_close();\n");
       
        $sess_id = $_COOKIE[$val];
        if ( $sess_id ) {
            show("session '$val' exists, resuming..\n");
            //unset($_SESSION);  // to make sure - this should be reloaded below
            session_name( $val );
            session_id( $sess_id );
            session_start();   // fills $_SESSION from the named session
        } else {
            show("creating new session '$val'...\n");
            session_name( $val );
            session_start();
            session_regenerate_id();  // create new (copy of old), leave old alone
            $_SESSION = array();  // wipe data clean for a fresh session
            show("regenerated ID and wiped SESSION superglobal\n");
        }
        show("Session name: \t" . session_name() . "\n");
        show("Session ID: \t" . session_id() . "\n");
    }
    else
    {
        if ( $_COOKIE[$key] ) {
            show("Cookie: \t'$key': \t'$val'\n");
        } else {
            show("Setting session var: \t'$key': \t'$val'\n");
            $_SESSION[$key] = $val;
        }
    }
}
show("----\nSession vars:\n");
show_sess_vars();
if ( false ) {
    session_write_close();
   
    session_name("edit_assembly");
    session_start();
    show("Session name: \t" . session_name() . "\n");
    show("Session ID: \t" . session_id() . "\n");
    show_sess_vars();
}

?>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html>
<head>
    <title> PHP session testing </title>
    <style type='text/css'>
    body { background-color: gray; }
    #content { background-color: white;  width: 70%;  margin: 1em auto 1em auto;  padding: 2em;
               font-family: Verdana, monospace;  font-size: 10pt; }
    </style>
</head>
<body>

<div id='content'>

    <h1> PHP session test: </h1>
   
    <pre><?php echo $messages; ?></pre>

</div>
</body>
</html>

webmaster at nncoders dot de (26-Jun-2008 05:29)

You can always just use "or".

@foo or bar();

When foo fails, (and the at still means don't print an error to the browser), the function bar will be executed.

<?php
   
    function errorhandler () { /* do something wild */ }
   
    @session_name('mysession') or errorhandler();
   
?>

Another live example would be
@mysql_query('show databases') or die(mysql_error());

When the execution fails, parameter die is called (with last mysql_error as given string parameter)

slave at codegrunt dot com (22-Dec-2004 10:03)

One gotcha I have noticed with session_name is that it will trigger a WARNING level error if the cookie or GET/POST variable value has something other than alphanumeric characters in it.  If your site displays warnings and uses PHP sessions this may be a way to enumerate at least some of your scripts: 

http://example.com/foo.php?session_name_here=(bad)

Warning: session_start(): The session id contains invalid characters, valid characters are only a-z, A-Z and 0-9 in /some/path/foo.php on line 666

I did not see anything in the docs suggesting that one had to sanitize the PHP session ID values before opening the session but that appears to be the case.

Unfortunately session_name() always returns true so you have to actually get to the point of assigning variables values before you know whether you have been passed bad session data (as far as I can see).  After the error has been generated in other words.

Cheers

Hongliang Qiang (27-May-2004 09:48)

This may sound no-brainer: the session_name() function will have no essential effect if you set session.auto_start to "true" in php.ini . And the obvious explanation is the session already started thus cannot be altered before the session_name() function--wherever it is in the script--is executed, same reason session_name needs to be called before session_start() as documented.

I know it is really not a big deal. But I had a quite hard time before figuring this out, and hope it might be helpful to someone like me.