


The use of php reflection classes and the introduction of Laravel's use of reflection
本篇文章给大家带来的内容是关于php反射类的使用及Laravel对反射的使用介绍,有一定的参考价值,有需要的朋友可以参考一下,希望对你有所帮助。
前言
PHP的反射类与实例化对象作用相反,实例化是调用封装类中的方法、成员,而反射类则是拆封类中的所有方法、成员变量,并包括私有方法等。就如“解刨”一样,我们可以调用任何关键字修饰的方法、成员。当然在正常业务中是建议不使用,比较反射类已经摒弃了封装的概念。
本章讲解反射类的使用及Laravel对反射的使用。
反射
反射类是PHP内部类,无需加载即可使用,你可以通过实例化 ReflectionClass
类去使用它。
方法
这里列举下PHP反射类常用的方法
方法名 | 注释 |
---|---|
ReflectionClass::getConstant | 获取定义过的一个常量 |
ReflectionClass::getConstants | 获取一组常量 |
ReflectionClass::getConstructor | 获取类的构造函数 |
ReflectionClass::getDefaultProperties | 获取默认属性 |
ReflectionClass::getDocComment | 获取文档注释 |
ReflectionClass::getEndLine | 获取最后一行的行数 |
ReflectionClass::getFileName | 获取定义类的文件名 |
ReflectionClass::getInterfaceNames | 获取接口(interface)名称 |
ReflectionClass::getMethods | 获取方法的数组 |
ReflectionClass::getModifiers | 获取类的修饰符 |
ReflectionClass::getName | 获取类名 |
ReflectionClass::getNamespaceName | 获取命名空间的名称 |
ReflectionClass::getParentClass | 获取父类 |
等等等等.... 所有关于类的方法、属性及其继承的父类、实现的接口都可以查询到。
详细文档请参考官网
栗子
<?php namespace A\B; class Foo { } $function = new \ReflectionClass('stdClass'); var_dump($function->inNamespace()); var_dump($function->getName()); var_dump($function->getNamespaceName()); var_dump($function->getShortName()); $function = new \ReflectionClass('A\\B\\Foo'); var_dump($function->inNamespace()); var_dump($function->getName()); var_dump($function->getNamespaceName()); var_dump($function->getShortName()); ?>
输出结果
bool(false) string(8) "stdClass" string(0) "" string(8) "stdClass" bool(true) string(7) "A\B\Foo" string(3) "A\B" string(3) "Foo"
Laravel
Laravel在实现服务容器加载时使用了反射类。现在我们开启“解刨”模式
入口文件
index.php
$app = require_once __DIR__.'/../bootstrap/app.php'; /* |-------------------------------------------------------------------------- | Run The Application |-------------------------------------------------------------------------- | | Once we have the application, we can handle the incoming request | through the kernel, and send the associated response back to | the client's browser allowing them to enjoy the creative | and wonderful application we have prepared for them. | */ $kernel = $app->make(Illuminate\Contracts\Http\Kernel::class); $response = $kernel->handle( $request = Illuminate\Http\Request::capture() ); $response->send(); $kernel->terminate($request, $response);
是引用语句发生的下一行调用了make方法。各位很清楚,make方法用于解析类,所有make方法的实现一定是在引用的文件内。
bootstrap\app.php
$app = new Illuminate\Foundation\Application( realpath(__DIR__.'/../') );
laravel开始加载它的核心类,所有的实现从 Illuminate\Foundation\Application
开始。
Illuminate\Foundation\Application
public function make($abstract, array $parameters = []) { $abstract = $this->getAlias($abstract); if (isset($this->deferredServices[$abstract]) && ! isset($this->instances[$abstract])) { $this->loadDeferredProvider($abstract); } return parent::make($abstract, $parameters); }
在核心类中你可能准确的查找到make方法的存在,它加载了服务提供者随后调用了父类的方法make,要知道作为独立的模块 “服务容器”是绝对不能写在核心类的。懂点设计模式的都很清楚。
Illuminate\Container\Container
以 $api = $this->app->make('HelpSpot\API',['id'=>1]);
为例来讲解
// 真正的make方法,它直接调用了resolve继续去实现make的功能 // $abstract = 'HelpSpot\API' public function make($abstract, array $parameters = []) { // $abstract = 'HelpSpot\API' return $this->resolve($abstract, $parameters); } ... protected function resolve($abstract, $parameters = []) { ... // 判断是否可以合理反射 // $abstract = 'HelpSpot\API' if ($this->isBuildable($concrete, $abstract)) { // 实例化具体实例 (实际并不是实例化,而是通过反射“解刨”了) $object = $this->build($concrete); } else { $object = $this->make($concrete); } ... } public function build($concrete) { // $concrete = 'HelpSpot\API' if ($concrete instanceof Closure) { return $concrete($this, $this->getLastParameterOverride()); } // 实例化反射类 $reflector = new ReflectionClass($concrete); // 检查类是否可实例化 if (! $reflector->isInstantiable()) { return $this->notInstantiable($concrete); } $this->buildStack[] = $concrete; // 获取类的构造函数 $constructor = $reflector->getConstructor(); if (is_null($constructor)) { array_pop($this->buildStack); return new $concrete; } $dependencies = $constructor->getParameters(); $instances = $this->resolveDependencies( $dependencies ); array_pop($this->buildStack); // 从给出的参数创建一个新的类实例。 return $reflector->newInstanceArgs($instances); }
可见一个服务容器就加载成功了。
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