PHP幾種回調寫法
在PHP中,匿名函數是最方便的回調寫法,但除了匿名函數方式的回調,PHP還有其他的回調寫法。以下是PHP幾種回調寫法的示例。
1、匿名函數回調
<?php
use Workerman\Worker;
use Workerman\Connection\TcpConnection;
use Workerman\Protocols\Http\Request;
require_once __DIR__ . '/vendor/autoload.php';
$http_worker = new Worker("http://0.0.0.0:2345");
// 匿名函數回調
$http_worker->onMessage = function(TcpConnection $connection, Request $data)
{
// 向瀏覽器發送hello world
$connection->send('hello world');
};
Worker::runAll();
2、普通函數回調
<?php
use Workerman\Worker;
use Workerman\Connection\TcpConnection;
use Workerman\Protocols\Http\Request;
require_once __DIR__ . '/vendor/autoload.php';
$http_worker = new Worker("http://0.0.0.0:2345");
// 匿名函數回調
$http_worker->onMessage = 'on_message';
// 普通函數
function on_message(TcpConnection $connection, Request $request)
{
// 向瀏覽器發送hello world
$connection->send('hello world');
}
Worker::runAll();
3、類方法作為回調
MyClass.php
use Workerman\Worker;
use Workerman\Connection\TcpConnection;
class MyClass{
public function __construct(){}
public function onWorkerStart(Worker $worker){}
public function onConnect(TcpConnection $connection){}
public function onMessage(TcpConnection $connection, $message) {}
public function onClose(TcpConnection $connection){}
public function onWorkerStop(Worker $worker){}
}
啟動腳本 start.php
<?php
use Workerman\Worker;
require_once __DIR__ . '/vendor/autoload.php';
// 載入MyClass
require_once __DIR__.'/MyClass.php';
$worker = new Worker("websocket://0.0.0.0:2346");
// 創建一個對象
$my_object = new MyClass();
// 調用類的方法
$worker->onWorkerStart = array($my_object, 'onWorkerStart');
$worker->onConnect = array($my_object, 'onConnect');
$worker->onMessage = array($my_object, 'onMessage');
$worker->onClose = array($my_object, 'onClose');
$worker->onWorkerStop = array($my_object, 'onWorkerStop');
Worker::runAll();
注意:
以上的代碼結構不允許在構造函數裡初始化資源(例如MySQL連接、Redis連接、Memcache連接等),因為$my_object = new MyClass();
運行在主進程。以MySQL為例,在主進程初始化的MySQL連接等資源會被子進程繼承,每個子進程都可以操作這個資料庫連接,但這些連接在MySQL服務端對應的是同一個連接,會發生不可預期的錯誤,例如mysql gone away
錯誤。
如果以上的代碼結構需要在類的構造函數裡初始化資源,可以採用以下寫法。
MyClass.php
use Workerman\Worker;
use Workerman\Connection\TcpConnection;
class MyClass{
protected $db = null;
public function __construct(){
// 假設資料庫連接類是MyDbClass
$db = new MyDbClass();
}
public function onWorkerStart(Worker $worker){}
public function onConnect(TcpConnection $connection){}
public function onMessage(TcpConnection $connection, $message) {}
public function onClose(TcpConnection $connection){}
public function onWorkerStop(Worker $worker){}
}
啟動腳本 start.php
<?php
use Workerman\Worker;
require_once __DIR__ . '/vendor/autoload.php';
$worker = new Worker("websocket://0.0.0.0:2346");
// 在onWorkerStart裡初始化類
$worker->onWorkerStart = function($worker) {
// 載入MyClass
require_once __DIR__.'/MyClass.php';
// 創建一個對象
$my_object = new MyClass();
// 調用類的方法
$worker->onConnect = array($my_object, 'onConnect');
$worker->onMessage = array($my_object, 'onMessage');
$worker->onClose = array($my_object, 'onClose');
$worker->onWorkerStop = array($my_object, 'onWorkerStop');
};
Worker::runAll();
上面的代碼結構中onWorkerStart運行時已經是屬於子進程,等於每個子進程各自建立自己的MySQL連接,所以不會有共享連接的問題。這樣還有一個好處就是支持業務代碼reload。由於MyClass.php是在子進程載入的,根據reload規則業務更改MyClass.php後直接reload即可生效。
4、類的靜態方法作為回調
靜態類MyClass.php
use Workerman\Worker;
use Workerman\Connection\TcpConnection;
class MyClass{
public static function onWorkerStart(Worker $worker){}
public static function onConnect(TcpConnection $connection){}
public static function onMessage(TcpConnection $connection, $message) {}
public static function onClose(TcpConnection $connection){}
public static function onWorkerStop(Worker $worker){}
}
啟動腳本 start.php
<?php
use Workerman\Worker;
require_once __DIR__ . '/vendor/autoload.php';
// 載入MyClass
require_once __DIR__.'/MyClass.php';
$worker = new Worker("websocket://0.0.0.0:2346");
// 調用類的靜態方法。
$worker->onWorkerStart = array('MyClass', 'onWorkerStart');
$worker->onConnect = array('MyClass', 'onConnect');
$worker->onMessage = array('MyClass', 'onMessage');
$worker->onClose = array('MyClass', 'onClose');
$worker->onWorkerStop = array('MyClass', 'onWorkerStop');
// 如果類帶命名空間,則是類似這樣的寫法
// $worker->onWorkerStart = array('your\namesapce\MyClass', 'onWorkerStart');
// $worker->onConnect = array('your\namesapce\MyClass', 'onConnect');
// $worker->onMessage = array('your\namesapce\MyClass', 'onMessage');
// $worker->onClose = array('your\namesapce\MyClass', 'onClose');
// $worker->onWorkerStop = array('your\namesapce\MyClass', 'onWorkerStop');
Worker::runAll();
注意:根據PHP的運行機制,如果沒有調用new則不會調用構造函數,另外靜態類的方法裡面不允許使用$this
。