php 钩子 实现

PHP 钩子实现方法

钩子（Hook）是一种在特定事件发生时插入自定义代码的机制，常用于插件系统或框架扩展。以下是几种常见的 PHP 钩子实现方式：

使用函数和全局变量

通过全局数组存储钩子函数，在特定事件触发时调用这些函数：

$hooks = [];

function add_hook($hook_name, $callback) {
    global $hooks;
    $hooks[$hook_name][] = $callback;
}

function do_hook($hook_name, $params = []) {
    global $hooks;
    if (isset($hooks[$hook_name])) {
        foreach ($hooks[$hook_name] as $callback) {
            call_user_func_array($callback, $params);
        }
    }
}

面向对象实现

采用面向对象方式封装钩子系统，提高可维护性：

class HookSystem {
    private $hooks = [];

    public function add($hook_name, $callback) {
        $this->hooks[$hook_name][] = $callback;
    }

    public function trigger($hook_name, $params = []) {
        if (isset($this->hooks[$hook_name])) {
            foreach ($this->hooks[$hook_name] as $callback) {
                call_user_func_array($callback, $params);
            }
        }
    }
}

优先级支持

为钩子添加优先级支持，控制执行顺序：

class PriorityHook {
    private $hooks = [];

    public function add($hook_name, $callback, $priority = 10) {
        $this->hooks[$hook_name][$priority][] = $callback;
    }

    public function trigger($hook_name, $params = []) {
        if (isset($this->hooks[$hook_name])) {
            ksort($this->hooks[$hook_name]);
            foreach ($this->hooks[$hook_name] as $priority => $callbacks) {
                foreach ($callbacks as $callback) {
                    call_user_func_array($callback, $params);
                }
            }
        }
    }
}

过滤器类型钩子

实现可修改返回值的过滤器钩子：

class FilterHook {
    private $filters = [];

    public function add($filter_name, $callback, $priority = 10) {
        $this->filters[$filter_name][$priority][] = $callback;
    }

    public function apply($filter_name, $value, $params = []) {
        if (isset($this->filters[$filter_name])) {
            ksort($this->filters[$filter_name]);
            foreach ($this->filters[$filter_name] as $priority => $callbacks) {
                foreach ($callbacks as $callback) {
                    $value = call_user_func_array($callback, array_merge([$value], $params));
                }
            }
        }
        return $value;
    }
}

实际应用示例

在框架中注册和使用钩子：

$hook = new HookSystem();

// 注册钩子
$hook->add('before_render', function($content) {
    return "<!-- Header -->" . $content;
});

// 触发钩子
$content = $hook->apply('before_render', '<div>Page Content</div>');

这些方法展示了PHP中实现钩子的不同方式，从简单到复杂，可根据项目需求选择适合的实现方案。