在PHP3中实现SESSION的功能（一）_php基础

SESSION函数库：session.inc.php3

if (!isset($__session_inc__)){
$__session_inc__=1;
//require("cookie.inc.php3");
# -------------------------------------------------------------------
# Session Management v1.0 21.6.1998
# (c) Wild Karl Heinz
#
# This Include handle Session based variable handling
#
# Please feel free and use it. If you make it more functional
# it would be nice to send me a copy.
#
# Don't forget - Mysql_connect !
#
# The database structure
# Table structure for table 'session'
#
# CREATE TABLE session (
# id int(11) DEFAULT '0' NOT NULL auto_increment,
# sid varchar(20) DEFAULT '' NOT NULL,
# val blob,
# times timestamp(14),
# PRIMARY KEY (id),
# KEY sid (sid),
# UNIQUE sid_2 (sid)
# );
#
# You'll miss here a cron job to delete the old sessions from db
# -------------------------------------------------------------------

// 请注意上面被注释掉的CREATE TABLE语句，
// 你需要在你所使用的数据库上执行这条语句，
// 表名也可以不是session，那么就需要设置下面的$sess_table变量了。

// 此处你需要设置库名，和表名。
// 不过一般建议就使用session作为表名
$sess_db = 'dbname';
$sess_table = 'session';

# ----------------------------------------------------
# Session_CheckID - 检查、设置并返回 Session-ID
# 参数......: cookie保存时间(以分钟计)
# 也可不设置表示这个 cookie 只在当前session 有效
# 这其实就象ASP中SESSION的时效一样。
# 返回值....: 一个唯一的Session-ID （作为cookie存储）
# ----------------------------------------------------
function Session_CheckID( $min )
{
global $sess_sid;

if( !$sess_sid ) {
$sess_sid = uniqid( SC ); //取得一个唯一的随机数
/*
if( $min > 0 ) {
SetCookie("sess_sid", $sess_sid, time()+($min*60), "/", "", 0 );
}
else {
SetCookie("sess_sid", $sess_sid, "", "/", "", 0 );
}
上面是原先的代码，会出错。所以另外用了一个更好的函数。
函数库：cookie.inc.php3
*/
jssetcookie("sess_sid",$sess_sid,$min);
return( false );
}
else {
return( true );
}
}

# ----------------------------------------------------------
# str2arr - 将字符串转换成session数组
# 参数.....: string
# 返回值...: 全局数组（其实就是session)
#本函数用途：将字符串转换成session数组
#如"session[username]=yourid&session[userpass]=12345"
#将会被转换成下面的数组
# session[username]="yourid"
# session[userpass]="12345"
#请注意函数split(),each(),list(),eval()的用法。
# ----------------------------------------------------------
function str2arr( $ts )
{
global $session;

$vals = split( "&", $ts );
while( list($key,$val) = each($vals) ) {
list( $name, $wert ) = split( "=", $val );
if( $val ) eval( "$$name = "$wert";" );
}
}

# ----------------------------------------------------------
# session_read() - 从SESSION表中取数据，转换成session数组
# 参数........: 无
# 返回值......: 如果读出数据，返回 true ，否则返回 false
#注意.........: 用到了str2arr()这个函数
# ----------------------------------------------------------
function session_read()
{
# Hash array to keep session-variables
global $session;
global $sess_sid, $sess_db, $sess_table, $sess_error;

$sel = "Select val from $sess_table where sid = '$sess_sid'";
$res = mysql_db_query( $sess_db, $sel );
if( mysql_numrows( $res ) ) {
$val = mysql_result( $res, 0, "val" );
str2arr( $val );
mysql_free_result( $res );
return( true );
}
else {
return( false );
$sess_error = mysql_error();
}
}

# ------------------------------------------------------
# Split_Array() - 将session数组转换成字符串
# 参数.......: 数组
# 返回值.....: 数组转换得来的字符串
#
# Thanks to Rasmus (这人好象是PHP的发明人)
# 注意:将session数组转换成字符串
#如session[username]="yourid"
# session[userpass]="12345"
#将会被转换成"session[username]=yourid&session[userpass]=12345"
#同时该函数考虑到了数组的某个元素也是数据的情况
#这个函数被设计成一个递归函数
# ------------------------------------------------------
function Split_Array( $arr, $a = "", $b = "", $c = "" )
{
while( list( $key, $val ) = each( $arr ) ) {
if( is_array( $val ) ) {
$ts .= Split_Array( $arr[ $key ],
( strlen( $a ) ? $a : $key ),
( strlen( $b ) ? $b : ( strlen( $a ) ? $key : "" ) ),
( strlen( $c ) ? $c : ( strlen( $b ) ? $key : "" ) ) );
}
else {
$ts .= "session";
$ts .= $a ? "[$a]" : "";
$ts .= $b ? "[$b]" : "";
$ts .= $c ? "[$c]" : "";
$ts .= "[$key]=$val&";
}
}
return( $ts );
}

# ---------------------------------------------------
# session_write - 将session数组转换成字符串，再存到session表中
# 参数.: 无
# 返回值...: 如果存入正常返回 true ，否则返回 false
# ---------------------------------------------------
function session_write()
{
# Hash array to keep session-variables
global $session;

global $sess_sid, $sess_db, $sess_table;
global $sess_error;

# if you like to delete a session-cookie
# you must check it before writting the session
# array

if( !$sess_sid ) { session_checkid( 0 ); }

$ts = Split_Array( $session );
if( $ts > "" ) { $ts = substr( $ts, 0, strlen( $ts ) - 1 ); }
$res = mysql_db_query( $sess_db, "Select * from session where sid = '$sess_s'");
if( mysql_numrows( $res ) == 0 ) {
$sel = "Insert into $sess_table ( id, sid, val, times ) ";
$sel .= "values( 0, '$sess_sid', '$ts', NULL )";
}
else {
$sel = "Update $sess_table set val = '$ts', ";
$sel .= "times = NULL where sid = '$sess_sid'";
}
if( !mysql_db_query( $sess_db, $sel ) ) {
$sess_error = mysql_error();
return( false );
}
else { return( true ); }
}

# ---------------------------------------------
# session_del - 清除当前所有的session
# 并删除session表中和当前session有关的记录
# 参数.....: 一个随机的session id
# 返回值...: 无
# ---------------------------------------------
function session_del()
{
global $session, $sess_db, $sess_table, $sess_sid;

$sel = "Delete from $sess_table where sid = '$sess_sid'";
if( !mysql_db_query( $sess_db, $sel ) ) {
$sess_error = mysql_error();
}
$sess_sid = '';
}
}
?>

原作者：不详