Php中session_set_save_handler的含义

chaosxin

今天看手册，无意中看到了session_set_save_handler不解其意，于是上网搜寻得知，可以使用session_set_save_handler函数重载SESSION存储方式存储于MYSQL，样例如下：

Code
1 <?php   
2   $DB_SERVER = "server"; /* database server hostname */
3   $DB_NAME = "dbname"; /* database name */
4   $DB_USER = "root"; /* database user */
5   $DB_PASS = "*************"; /* database password */
6   
7   $DB_SELECT_DB = "";
8   $SESS_LIFE = get_cfg_var("session.gc_maxlifetime");
9   
10  function sess_open($save_path, $session_name) {
11  global $DB_SERVER, $DB_NAME, $DB_USER, $DB_PASS, $DB_SELECT_DB;
12   
13  if (! $DB_SELECT_DB = mysql_pconnect($DB_SERVER, $DB_USER, $DB_PASS)) {
14  echo "SORRY! MYSQL ERROR : Can't connect to $DB_SERVER as $DB_USER";
15  echo "MySQL Error: ", mysql_error();
16  die;
17  }
18   
19  if (! mysql_select_db($DB_NAME, $DB_SELECT_DB)) {
20  echo "SORRY! MYSQL ERROR : Unable to select database $DB_NAME";
21  die;
22  }
23   
24  return true;
25  }
26   
27  function sess_close() {
28  return true;
29  }
30   
31  function sess_read($SessionKey){
32        global $DB_SELECT_DB, $SESS_LIFE;   
33        $Query = "SELECT SessionArray FROM cdb_global_sessions WHERE SessionKey = '".$SessionKey."' AND SessionExpTime > " . time();
34        $Result = mysql_query($Query, $DB_SELECT_DB);
35   
36  if (list($SessionArray) = mysql_fetch_row($Result)) {
37  return $SessionArray;
38  }
39   
40  return false;
41  }
42   
43  function sess_write($SessionKey, $VArray) {
44  global $DB_SELECT_DB, $SESS_LIFE;
45   
46  $SessionExpTime = time() + $SESS_LIFE;
47  $SessionArray = addslashes($VArray);
48   
49  $Query = "INSERT INTO cdb_global_sessions (SessionKey,SessionExpTime,SessionArray) VALUES ('".$SessionKey."','".$SessionExpTime."','".$SessionArray."')";
50  $Result = mysql_query($Query, $DB_SELECT_DB);
51   
52  if (!$Result){
53  $Query = "UPDATE cdb_global_sessions SET SessionExpTime = '".$SessionExpTime."', SessionArray = '".$SessionArray."' WHERE SessionKey = '".$SessionKey."' AND SessionExpTime > " . time();
54  $Result = mysql_query($Query, $DB_SELECT_DB);
55  }   
56  return $Result;
57  }
58   
59  function sess_destroy($SessionKey) {
60  global $DB_SELECT_DB;
61   
62  $Query = "DELETE FROM cdb_global_sessions WHERE SessionKey = '".$SessionKey."'";
63  $Result = mysql_query($Query, $DB_SELECT_DB);
64   
65  return $Result;
66  }
67   
68  function sess_gc($maxlifetime) {
69  global $DB_SELECT_DB;
70   
71  $Query = "DELETE FROM cdb_global_sessions WHERE SessionExpTime < " . time();
72  $Result = mysql_query($Query, $DB_SELECT_DB);
73   
74  return mysql_affected_rows($DB_SELECT_DB);
75  }
76   
77  session_set_save_handler(
78  "sess_open",
79  "sess_close",
80  "sess_read",
81  "sess_write",
82  "sess_destroy",
83  "sess_gc");
84session_start();
85  ?>
86