摘要：當調用時，會觸發當前類的魔術方法，通過判斷屬性中索引是否存在，不存在拋出異常，存在就通過去實例化初始化時設置的，這里是工廠模式，接下來的路由文章會詳細分析。在操作中，會將前置操作設置到類的屬性中。微框架源碼閱讀系列

在自動加載實現完成后，接著new flightEngine()自動加載的方式實例化了下框架的核心類Engine，這個類名翻譯過來就是引擎發動機的意思，是flight的引擎發動機，很有想象力吧。

public static function app() {
    static $initialized = false;

    if (!$initialized) {
        require_once __DIR__."/autoload.php";

        self::$engine = new flightEngine();

        $initialized = true;
    }

    return self::$engine;
}

在實例化Engine這個類的時候，當前類的構造方法進行了對框架的初始化工作。

public function __construct() {
    $this->vars = array();

    $this->loader = new Loader();
    $this->dispatcher = new Dispatcher();

    $this->init();
}

接著來看init方法都做了什么，將初始化狀態標記為靜態變量static $initialized，判斷如果為true，將$this->vars以及$this->loader、$this->dispatcher中保存的屬性重置為默認狀態。

static $initialized = false;
$self = $this;

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

接下來將框架的Request、Response、Router、View類的命定空間地址register（設置）到Loader類的classes屬性中。

// 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

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

    $this->classes[$name] = array($class, $params, $callback);
}

再接下來就是將框架給用戶提供的調用方法，設置到調度器Dispatcher類的events屬性中。

// 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

/**
 * 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;
}

接下來呢，就是設置框架的一些配置，將這些配置保存在Engine類的vars屬性中。

// 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

/**
 * 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，當調用框架的start方法時，給其設置一些前置操作，通過set_error_handler()和set_exception_handler()設置用戶自定義的錯誤和異常處理函數，如何使用自定義的錯誤和異常函數，可以看這兩個范例:https://segmentfault.com/n/13...
https://segmentfault.com/n/13...。

// 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;

/**
 * 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);
}

當調用$self->router()時，會觸發當前類的__call()魔術方法，通過$this->loader->get($name)判斷屬性$classes中router索引是否存在，不存在拋出異常，存在就通過$this->loader->load($name, $shared)去實例化初始化時設置的"flight etRouter"，這里是工廠模式，接下來的路由文章會詳細分析。

/**
 * 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$this->before()操作中，會將前置操作設置到Dispatcher類的filters屬性中。這些操作完成后，將$initialized = true。

/**
 * 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

/**
 * 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源碼閱讀系列