php微框架 flight源码阅读——2.框架初始化、Loader、Dispatcher

摘要：当调用时，会触发当前类的魔术方法，通过判断属性中索引是否存在，不存在抛出异常，存在就通过去实例化初始化时设置的，这里是工厂模式，接下来的路由文章会详细分析。在操作中，会将前置操作设置到类的属性中。微框架源码阅读系列

在自动加载实现完成后，接着new flightEngine()自动加载的方式实例化了下框架的核心类Engine，这个类名翻译过来就是引擎发动机的意思，是flight的引擎发动机，很有想象力吧。

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public static function app() {
    static $initialized = false;
    if (!$initialized) {
        require_once __DIR__."/autoload.php";
        self::$engine = new flightEngine();
        $initialized = true;
    }
    return self::$engine;
}

在实例化Engine这个类的时候，当前类的构造方法进行了对框架的初始化工作。

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public function __construct() {
    $this->vars = array();
    $this->loader = new Loader();
    $this->dispatcher = new Dispatcher();
    $this->init();
}

接着来看init方法都做了什么，将初始化状态标记为静态变量static $initialized，判断如果为true，将$this->vars以及$this->loader、$this->dispatcher中保存的属性重置为默认状态。

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static $initialized = false;
$self = $this;
if ($initialized) {
    $this->vars = array();
    $this->loader->reset();
    $this->dispatcher->reset();
}

接下来将框架的Request、Response、Router、View类的命定空间地址register（设置）到Loader类的classes属性中。

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// Register default components
$this->loader->register("request", "flight
etRequest");
$this->loader->register("response", "flight
etResponse");
$this->loader->register("router", "flight
etRouter");
$this->loader->register("view", "flight
emplateView", array(), function($view) use ($self) {
    $view->path = $self->get("flight.views.path");
    $view->extension = $self->get("flight.views.extension");
});  

flight/core/Loader.php

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public function register($name, $class, array $params = array(), $callback = null) {
    unset($this->instances[$name]);
    $this->classes[$name] = array($class, $params, $callback);
}

再接下来就是将框架给用户提供的调用方法，设置到调度器Dispatcher类的events属性中。

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// Register framework methods
$methods = array(
    "start","stop","route","halt","error","notFound",
    "render","redirect","etag","lastModified","json","jsonp"
);
foreach ($methods as $name) {
    $this->dispatcher->set($name, array($this, "_".$name));
}

flight/core/Dispatcher.php

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/**
 * Assigns a callback to an event.
 *
 * @param string $name Event name
 * @param callback $callback Callback function
 */
public function set($name, $callback) {
    $this->events[$name] = $callback;
}

接下来呢，就是设置框架的一些配置，将这些配置保存在Engine类的vars属性中。

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// Default configuration settings
$this->set("flight.base_url", null);
$this->set("flight.case_sensitive", false);
$this->set("flight.handle_errors", true);
$this->set("flight.log_errors", false);
$this->set("flight.views.path", "./views");
$this->set("flight.views.extension", ".php");

flight/Engine.php

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/**
 * Sets a variable.
 *
 * @param mixed $key Key
 * @param string $value Value
 */
public function set($key, $value = null) {
    if (is_array($key) || is_object($key)) {
        foreach ($key as $k => $v) {
            $this->vars[$k] = $v;
        }
    }
    else {
        $this->vars[$key] = $value;
    }
}

最后一步的操作，当调用框架的start方法时，给其设置一些前置操作，通过set_error_handler()和set_exception_handler()设置用户自定义的错误和异常处理函数，如何使用自定义的错误和异常函数，可以看这两个范例:https://segmentfault.com/n/13...
https://segmentfault.com/n/13...。

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// Startup configuration
$this->before("start", function() use ($self) {
    // Enable error handling
    if ($self->get("flight.handle_errors")) {
        set_error_handler(array($self, "handleError"));
        set_exception_handler(array($self, "handleException"));
    }
    // Set case-sensitivity
    $self->router()->case_sensitive = $self->get("flight.case_sensitive");
});
$initialized = true;

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/**
 * Custom error handler. Converts errors into exceptions.
 *
 * @param int $errno Error number
 * @param int $errstr Error string
 * @param int $errfile Error file name
 * @param int $errline Error file line number
 * @throws ErrorException
 */
public function handleError($errno, $errstr, $errfile, $errline) {
    if ($errno & error_reporting()) {
        throw new ErrorException($errstr, $errno, 0, $errfile, $errline);
    }
}
/**
 * Custom exception handler. Logs exceptions.
 *
 * @param Exception $e Thrown exception
 */
public function handleException($e) {
    if ($this->get("flight.log_errors")) {
        error_log($e->getMessage());
    }
    $this->error($e);
}

当调用$self->router()时，会触发当前类的__call()魔术方法，通过$this->loader->get($name)判断属性$classes中router索引是否存在，不存在抛出异常，存在就通过$this->loader->load($name, $shared)去实例化初始化时设置的"flight etRouter"，这里是工厂模式，接下来的路由文章会详细分析。

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/**
 * Handles calls to class methods.
 *
 * @param string $name Method name
 * @param array $params Method parameters
 * @return mixed Callback results
 * @throws Exception
 */
public function __call($name, $params) {
    $callback = $this->dispatcher->get($name);
 
    if (is_callable($callback)) {
        return $this->dispatcher->run($name, $params);
    }
    if (!$this->loader->get($name)) {
        throw new Exception("{$name} must be a mapped method.");
    }
    $shared = (!empty($params)) ? (bool)$params[0] : true;
    return $this->loader->load($name, $shared);
}

在$this->before()操作中，会将前置操作设置到Dispatcher类的filters属性中。这些操作完成后，将$initialized = true。

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/**
 * Adds a pre-filter to a method.
 *
 * @param string $name Method name
 * @param callback $callback Callback function
 */
public function before($name, $callback) {
    $this->dispatcher->hook($name, "before", $callback);
}

flight/core/Dispatcher.php

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/**
 * Hooks a callback to an event.
 *
 * @param string $name Event name
 * @param string $type Filter type
 * @param callback $callback Callback function
 */
public function hook($name, $type, $callback) {
    $this->filters[$name][$type][] = $callback;
}

php微框架 flight源码阅读系列