Lumen开发：lumen源码解读之初始化(2)——门面(Facades)与数据库(db)
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紧接上一篇
$app->withFacades();//为应用程序注册门面。 $app->withEloquent();//为应用程序加载功能强大的库。
先来看看withFacades()
/**
* Register the facades for the application.（为应用程序注册门面。）
*
* @param bool $aliases
* @param array $userAliases
* @return void
*/
public function withFacades($aliases = true, $userAliases = [])
{
Facade::setFacadeApplication($this);
if ($aliases) {
$this->withAliases($userAliases);
}
}
setFacadeApplication()
/**
* Set the application instance.(设置应用程序实例。)
*
* @param \Illuminate\Contracts\Foundation\Application $app
* @return void
*/
public static function setFacadeApplication($app)
{
static::$app = $app;
}
将当前实例传给门面类(Facade)
$this->withAliases($userAliases)
/**
* Register the aliases for the application.(注册应用程序的别名。)
*
* @param array $userAliases
* @return void
*/
public function withAliases($userAliases = [])
{
$defaults = [
'Illuminate\Support\Facades\Auth' => 'Auth',
'Illuminate\Support\Facades\Cache' => 'Cache',
'Illuminate\Support\Facades\DB' => 'DB',
'Illuminate\Support\Facades\Event' => 'Event',
'Illuminate\Support\Facades\Gate' => 'Gate',
'Illuminate\Support\Facades\Log' => 'Log',
'Illuminate\Support\Facades\Queue' => 'Queue',
'Illuminate\Support\Facades\Schema' => 'Schema',
'Illuminate\Support\Facades\URL' => 'URL',
'Illuminate\Support\Facades\Validator' => 'Validator',
];
if (! static::$aliasesRegistered) {//判断是否已注册类别名。
static::$aliasesRegistered = true;
$merged = array_merge($defaults, $userAliases);
foreach ($merged as $original => $alias) {
class_alias($original, $alias);//设置别名
}
}
}
然后就是withEloquent()函数
/**
* Load the Eloquent library for the application.(为应用程序加载功能强大的库。)
*
* @return void
*/
public function withEloquent()
{
$this->make('db');
}
/**
* Resolve the given type from the container.（从容器中解析给定类型。）
*
* @param string $abstract
* @return mixed
*/
public function make($abstract)
{
$abstract = $this->getAlias($abstract);
if (array_key_exists($abstract, $this->availableBindings) &&
! array_key_exists($this->availableBindings[$abstract], $this->ranServiceBinders)) {
$this->{$method = $this->availableBindings[$abstract]}();
$this->ranServiceBinders[$method] = true;
}
return parent::make($abstract);
}
一步一步来，make()函数以后经常用得上。
/**
* Get the alias for an abstract if available.（如果可用的话，获取抽象的别名。）
*
* @param string $abstract
* @return string
*
* @throws \LogicException
*/
public function getAlias($abstract)
{
if (! isset($this->aliases[$abstract])) { //$this->aliases是注册类别名，如果没有别名，则直接返回$abstract
return $abstract;
}
if ($this->aliases[$abstract] === $abstract) { //如果$abstract是别名本身，则会抛出异常
throw new LogicException("[{$abstract}] is aliased to itself.");
}
return $this->getAlias($this->aliases[$abstract]);
}
这一个的$this->aliases的值来着上一篇文章registerContainerAliases()函数对它的赋值
接下来是这段
if (array_key_exists($abstract, $this->availableBindings) &&
! array_key_exists($this->availableBindings[$abstract], $this->ranServiceBinders)) {
$this->{$method = $this->availableBindings[$abstract]}();
$this->ranServiceBinders[$method] = true;
}
$this->availableBindings变量在Applilcation类的定义是是
/**
* The available container bindings and their respective load methods.（可用的容器绑定及其各自的加载方法。）
*
* @var array
*/
public $availableBindings = [
'auth' => 'registerAuthBindings',
'auth.driver' => 'registerAuthBindings',
'Illuminate\Auth\AuthManager' => 'registerAuthBindings',
'Illuminate\Contracts\Auth\Guard' => 'registerAuthBindings',
'Illuminate\Contracts\Auth\Access\Gate' => 'registerAuthBindings',
'Illuminate\Contracts\Broadcasting\Broadcaster' => 'registerBroadcastingBindings',
'Illuminate\Contracts\Broadcasting\Factory' => 'registerBroadcastingBindings',
'Illuminate\Contracts\Bus\Dispatcher' => 'registerBusBindings',
'cache' => 'registerCacheBindings',
'cache.store' => 'registerCacheBindings',
'Illuminate\Contracts\Cache\Factory' => 'registerCacheBindings',
'Illuminate\Contracts\Cache\Repository' => 'registerCacheBindings',
'composer' => 'registerComposerBindings',
'config' => 'registerConfigBindings',
'db' => 'registerDatabaseBindings',
'Illuminate\Database\Eloquent\Factory' => 'registerDatabaseBindings',
'encrypter' => 'registerEncrypterBindings',
'Illuminate\Contracts\Encryption\Encrypter' => 'registerEncrypterBindings',
'events' => 'registerEventBindings',
'Illuminate\Contracts\Events\Dispatcher' => 'registerEventBindings',
'files' => 'registerFilesBindings',
'hash' => 'registerHashBindings',
'Illuminate\Contracts\Hashing\Hasher' => 'registerHashBindings',
'log' => 'registerLogBindings',
'Psr\Log\LoggerInterface' => 'registerLogBindings',
'queue' => 'registerQueueBindings',
'queue.connection' => 'registerQueueBindings',
'Illuminate\Contracts\Queue\Factory' => 'registerQueueBindings',
'Illuminate\Contracts\Queue\Queue' => 'registerQueueBindings',
'Psr\Http\Message\ServerRequestInterface' => 'registerPsrRequestBindings',
'Psr\Http\Message\ResponseInterface' => 'registerPsrResponseBindings',
'translator' => 'registerTranslationBindings',
'url' => 'registerUrlGeneratorBindings',
'validator' => 'registerValidatorBindings',
'Illuminate\Contracts\Validation\Factory' => 'registerValidatorBindings',
'view' => 'registerViewBindings',
'Illuminate\Contracts\View\Factory' => 'registerViewBindings',
];
$this->ranServiceBinders变量是记录已执行的服务绑定方法。
当前执行的是make('db'),所以$abstract=‘db’;
$this->availableBindings['db'] = 'registerDatabaseBindings';
$this->{$method = $this->availableBindings[$abstract]}();
会执行到Application的registerDatabaseBindings方法
/**
* Register container bindings for the application.（为应用程序注册容器绑定。）
*
* @return void
*/
protected function registerDatabaseBindings()
{
$this->singleton('db', function () { //这里是用闭包函数注册一个db的单例
return $this->loadComponent(
'database', [
'Illuminate\Database\DatabaseServiceProvider',
'Illuminate\Pagination\PaginationServiceProvider',
], 'db'
);
});
}
这里是用闭包函数注册一个db的单例，接着看闭包内执行了什么
/**
* Configure and load the given component and provider.（配置并加载给定的组件和提供程序。）
*
* @param string $config
* @param array|string $providers
* @param string|null $return
* @return mixed
*/
public function loadComponent($config, $providers, $return = null)
{
$this->configure($config);//将配置文件加载到应用程序中。
foreach ((array) $providers as $provider) {
$this->register($provider);//注册传过来的服务供应类
}
return $this->make($return ?: $config);//
}
因为这里第一次初始化后，$this->ranServiceBinders[$method]=true,所以以后调用db时，都会直接调用父类(Container)的make()函数。
讲远了的感觉，不过刚好可以一起讲一下最后一步return parent::make($abstract);
/**
* Resolve the given type from the container.
*
* @param string $abstract
* @return mixed
*/
public function make($abstract)
{
return $this->resolve($abstract);
}
Container类的make()只调用了$this->resolve()函数，马不停蹄，我们来看看这个函数
/**
* Resolve the given type from the container.（从容器中解析给定类型。）
*
* @param string $abstract
* @param array $parameters
* @return mixed
*/
protected function resolve($abstract, $parameters = [])
{
$abstract = $this->getAlias($abstract);//取实际类名
$needsContextualBuild = ! empty($parameters) || ! is_null(
$this->getContextualConcrete($abstract)
);
//如果该类型的实例目前作为单例管理，
//我们将只返回一个现有的实例而不是实例化新的实例，
//所以开发人员每次都可以继续使用同一个对象实例。
if (isset($this->instances[$abstract]) && ! $needsContextualBuild) { //单例已存在直接返回
return $this->instances[$abstract];
}
$this->with[] = $parameters;
$concrete = $this->getConcrete($abstract); //返回给定抽象的具体类型（包括一些关于上下文的绑定操作）
//我们已经准备好实例化绑定注册的具体类型的实例。
//这将实例化类型，以及递归地解析所有的“嵌套”依赖关系，直到所有问题都得到解决为止。
if ($this->isBuildable($concrete, $abstract)) { //判断是否为递归
$object = $this->build($concrete); //递归用build(),用make()会死循环
} else {
$object = $this->make($concrete); //非递归用make()
}
//如果我们定义了这种类型的扩展程序，
//我们需要将它们旋转并将它们应用到正在构建的对象中。
//这允许扩展服务，例如更改配置或装饰对象。
foreach ($this->getExtenders($abstract) as $extender) { //执行扩展
$object = $extender($object, $this);
}
//如果请求的类型被注册为单例，我们将缓存“内存”中的实例，
//以便稍后返回它，而不必为每一个后续请求创建一个对象的全新实例。
if ($this->isShared($abstract) && ! $needsContextualBuild) {
$this->instances[$abstract] = $object;
}
$this->fireResolvingCallbacks($abstract, $object); //回调
//返回之前，我们还将解析的标志设置为“true”，
//并弹出此构建的参数重写。完成这两件事后，我们将准备返回完全构造的类实例。
$this->resolved[$abstract] = true;
array_pop($this->with); //移除最后一个键值，也就是$this->with[] = $parameters;
return $object;
}
这里是整篇文比较难的地方，部分注释是直译的，讲了这么久，其实也执行了$app->withFacades()和$app->withEloquent();
其实后面的一些注册和绑定与前面也是类似的，希望能帮到大家！
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版权声明：本文为博主原创文章，未经博主允许不得转载。
