如何为Symfony配置两套不同的session存储以适配前后台需求

你提出的配置双会话处理器的思路是完全可行的，不需要从零开发完整的自定义SessionHandler，只要增加一个代理分发层即可实现按访问场景分配存储介质的需求，具体实现步骤如下：

1. 配置基础会话处理器 #

先在config/packages/framework.yaml中声明你需要的两套原生处理器：

framework:
    session:
        handler_id: App\Session\DelegatingSessionHandler
        # 其他session基础配置（cookie有效期、名称等）照常编写即可

services:
    # 后台用默认文件存储处理器
    session.handler.native_file:
        class: Symfony\Component\HttpFoundation\Session\Storage\Handler\NativeFileSessionHandler
        arguments: ['%kernel.cache_dir%/sessions']

    # 前台用数据库存储处理器，直接用Symfony自带的PDOSessionHandler
    session.handler.pdo:
        class: Symfony\Component\HttpFoundation\Session\Storage\Handler\PdoSessionHandler
        arguments:
            $pdoOrDsn: '%env(DATABASE_URL)%'
            $options:
                db_table: 'sessions'
                db_id_col: 'session_id'
                db_data_col: 'session_data'
                db_time_col: 'session_lifetime'

2. 编写分发代理SessionHandler #

自定义一个实现SessionHandlerInterface的代理类，根据当前请求的路由/防火墙动态选择调用对应的处理器：

<?php
namespace App\Session;

use Symfony\Component\HttpFoundation\RequestStack;
use SessionHandlerInterface;

class DelegatingSessionHandler implements SessionHandlerInterface
{
    private $adminHandler;
    private $frontHandler;
    private $requestStack;

    public function __construct(
        SessionHandlerInterface $adminHandler,
        SessionHandlerInterface $frontHandler,
        RequestStack $requestStack
    ) {
        $this->adminHandler = $adminHandler;
        $this->frontHandler = $frontHandler;
        $this->requestStack = $requestStack;
    }

    private function getActiveHandler(): SessionHandlerInterface
    {
        $request = $this->requestStack->getCurrentRequest();
        // 两种判断规则二选一即可：
        // 方案1：按路由前缀判断，例后台路由均以/admin开头
        if ($request && strpos($request->getPathInfo(), '/admin') === 0) {
            return $this->adminHandler;
        }
        // 方案2：按防火墙名称判断，需要安装security-bundle
        // $firewallContext = $request->attributes->get('_firewall_context');
        // $firewallName = $firewallContext ? explode('.', $firewallContext)[1] : null;
        // if ($firewallName === 'admin') {
        //     return $this->adminHandler;
        // }
        return $this->frontHandler;
    }

    public function open($savePath, $sessionName): bool
    {
        return $this->getActiveHandler()->open($savePath, $sessionName);
    }

    public function close(): bool
    {
        return $this->getActiveHandler()->close();
    }

    public function read($sessionId): string|false
    {
        return $this->getActiveHandler()->read($sessionId);
    }

    public function write($sessionId, $sessionData): bool
    {
        return $this->getActiveHandler()->write($sessionId, $sessionData);
    }

    public function destroy($sessionId): bool
    {
        return $this->getActiveHandler()->destroy($sessionId);
    }

    public function gc($maxLifetime): int|false
    {
        // 垃圾回收时同步清理两个存储的过期数据，避免冗余
        return $this->adminHandler->gc($maxLifetime) + $this->frontHandler->gc($maxLifetime);
    }
}

3. 绑定服务参数 #

在config/services.yaml中为代理类注入对应的处理器实例：

services:
    App\Session\DelegatingSessionHandler:
        arguments:
            $adminHandler: '@session.handler.native_file'
            $frontHandler: '@session.handler.pdo'

4. 初始化数据库存储表 #

如果使用MySQL作为前台session存储，执行建表语句即可：

CREATE TABLE `sessions` (
    `session_id` VARCHAR(128) NOT NULL PRIMARY KEY,
    `session_data` BLOB NOT NULL,
    `session_lifetime` INTEGER UNSIGNED NOT NULL,
    `session_time` INTEGER UNSIGNED NOT NULL
) COLLATE utf8mb4_bin, ENGINE = InnoDB;

内容的提问来源于stack exchange，提问作者chaillouvincent