php - session 不会保存到 mysql

Question

我有一个文件 sess_function.php

此文件列出了用于控制 session 的各种 (6) 函数。

function _open()
{
    try{
        // Open the database
        $dbh = new PDO("mysql:host=$host;dbname=$dbname",$user,$pass);
        $dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );  
    } //try
    catch(PDOException $e){
        echo "Oops, We're experiencing an error CONNECTING.";
        file_put_contents('PDODBConnectionErrors.txt', $e->getMessage(), FILE_APPEND);  
    } //catch
}   

## Kill Connection to Mysql (Using PDO) 
function _close(){
$dbh = null;
}

## Read a current session 
function _read($id){
    try{
        // Open the database
        $dbh = new PDO("mysql:host=$host;dbname=$dbname",$user,$pass);
        $dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );  
        // Begin Query
        $id = mysql_real_escape_string($id);
        $sth = $dbh->prepare("SELECT data FROM sessions WHERE id = '$id'");
        $sth->execute();

    }
    catch(PDOException $e){
        echo "Oops, We're experiencing an error. READING";
        file_put_contents('PDODBConnectionErrors.txt', $e->getMessage(), FILE_APPEND);  
    } //catch

    ## return '';
}

## Write to current session 
function _write($id, $data){
    // WRITE Vars
    try{
        // Open the database
##      require_once('dbi.php');
        $dbh = new PDO("mysql:host=$host;dbname=$dbname",$user,$pass);
        $dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );  
        // Begin Query
        $access = time();
        $id = mysql_real_escape_string($id);
        $access = mysql_real_escape_string($access);
        $data = mysql_real_escape_string($data);
        $sth = $dbh->prepare("REPLACE INTO sessions VALUES ('$id', '$access', '$data')");
        $sth->execute();
    }
    catch(PDOException $e){
        echo "Oops, We're experiencing an error. REPLACING SESSION VAL";
        file_put_contents('PDODBConnectionErrors.txt', $e->getMessage(), FILE_APPEND);  
    } //catch

}

## Destroy current session
function _destroy($id){   
    try{
        // Open the database
##      require_once('dbi.php');
        $dbh = new PDO("mysql:host=$host;dbname=$dbname",$user,$pass);
        $dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );  
        // Begin Query
        $id = mysql_real_escape_string($id);
        $sth = $dbh->prepare("DELETE FROM sessions WHERE id = '$id'");
        $sth->execute();
    }
    catch(PDOException $e){
        echo "Oops, We're experiencing an error.";
        file_put_contents('PDODBConnectionErrors.txt', $e->getMessage(), FILE_APPEND);  
    } //catch  
}

## Clean old session data out 
function _clean($max){
    try{
        // Open the database
##      require_once('dbi.php');
        $dbh = new PDO("mysql:host=$host;dbname=$dbname",$user,$pass);
        $dbh->setAttribute( PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION );  
        // Begin Query
        $old = time() - $max;
        $old = mysql_real_escape_string($old);
        $sth = $dbh->prepare("DELETE FROM sessions WHERE  access < '$old'");
        $sth->execute();
    }
    catch(PDOException $e){
        echo "Oops, We're experiencing an error. DEL FROM SESSION";
        file_put_contents('PDODBConnectionErrors.txt', $e->getMessage(), FILE_APPEND);  
    } //catch

}

和index.php

////////////////////////////////////////////////////////////////////////////////////
###### Require Database ######                              ////////////////////////
####### DB Config Setting #######
$host ='localhost'; //////////////
$dbname ='mydb';//////////
$user ='root';     //////////////
$pass ='';         //////////////
/////////////////////////////////


                        ////////////////////////
////////////////////////////////////////////////////////////////////////////////////
###### Start session                                        ////////////////////////
session_start();                                            ////////////////////////
###### Call Session Functions Include ######                ////////////////////////            
require_once('src/cfg/sess_function.php');                  ////////////////////////
###### Call function as contained in sess_function() ######                       //
session_set_save_handler('_open','_close','_read','_write','_destroy','_clean');  //                            
////////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////////

该表如下所示:

问题是:它没有给我带来任何问题，但是 sessions 表中没有存储任何内容...

如果我取消注释 session_start(); 它会抛出这些警告:

Oops, We're experiencing an error. READING
Warning: session_start() Cannot send session cookie - headers already sent by sess_function.php:33)index.php on line 12

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started sess_function.php:33) in index.php on line 12

有人吗？

Answer 1

您应该查看第一条错误消息。 PHP 需要发送 HTTP header 数据(cookie)，但 sess_function.php 中已经有一些输出。常规输出后无法发送 header 数据(例如 echo)。您打印“哎呀，我们遇到错误。正在阅读”，这是 PHP 提示的输出。删除所有 echo 语句将解决 session 问题。

然后:$dbname、$user、$pass 和 $host 变量未设置。 global $dbname, $host, $user, $pass; 声明修复了这个问题。

最后:session_set_save_handler必须在session_start之前调用，否则PHP将不会调用自定义函数。发生输出已发送错误是因为在 session_start 完成运行之前触发了 MySQL 错误(MySQL 错误发生在 session_start 期间)