Laravel实现构造函数自动依赖注入的方法
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《:Laravel实现构造函数自动依赖注入的方法》要点: 本篇章节讲解Laravel实现构造函数自动依赖注入的办法.分享给大家供大家参考,具体如下:PHP编程 在Laravel的构造函数中可以实现自动依赖注入,而不需要实例化之前先实例化需要的类,如代码所示:PHP编程
<?php
namespace LioHttpControllersForum;
use LioForumRepliesReplyRepository;
use LioForumThreadsThreadCreator;
use LioForumThreadsThreadCreatorListener;
use LioForumThreadsThreadDeleterListener;
use LioForumThreadsThreadForm;
use LioForumThreadsThreadRepository;
use LioForumThreadsThreadUpdaterListener;
use LioHttpControllersController;
use LioTagsTagRepository;
class ForumThreadsController extends Controller implements ThreadCreatorListener,ThreadUpdaterListener,ThreadDeleterListener
{
protected $threads;
protected $tags;
protected $currentSection;
protected $threadCreator;
public function __construct(
ThreadRepository $threads,ReplyRepository $replies,TagRepository $tags,ThreadCreator $threadCreator
) {
$this->threads = $threads;
$this->tags = $tags;
$this->threadCreator = $threadCreator;
$this->replies = $replies;
}
}
注意构造函数中的几个类型约束,其实并没有地方实例化这个Controller并把这几个类型的参数传进去,Laravel会自动检测类的构造函数中的类型约束参数,并自动识别是否初始化并传入.PHP编程 源码vendor/illuminate/container/Container.php中的build办法:PHP编程 $constructor = $reflector->getConstructor(); dump($constructor); 这里会解析类的构造函数,在这里打印看:PHP编程
它会找出构造函数的参数,再看完整的build办法进行的操作:PHP编程
public function build($concrete,array $parameters = [])
{
// If the concrete type is actually a Closure,we will just execute it and
// hand back the results of the functions,which allows functions to be
// used as resolvers for more fine-tuned resolution of these objects.
if ($concrete instanceof Closure) {
return $concrete($this,$parameters);
}
$reflector = new ReflectionClass($concrete);
// If the type is not instantiable,the developer is attempting to resolve
// an abstract type such as an Interface of Abstract Class and there is
// no binding registered for the abstractions so we need to bail out.
if (! $reflector->isInstantiable()) {
$message = "Target [$concrete] is not instantiable.";
throw new BindingResolutionContractException($message);
}
$this->buildStack[] = $concrete;
$constructor = $reflector->getConstructor();
// If there are no constructors,that means there are no dependencies then
// we can just resolve the instances of the objects right away,without
// resolving any other types or dependencies out of these containers.
if (is_null($constructor)) {
array_pop($this->buildStack);
return new $concrete;
}
$dependencies = $constructor->getParameters();
// Once we have all the constructor's parameters we can create each of the
// dependency instances and then use the reflection instances to make a
// new instance of this class,injecting the created dependencies in.
$parameters = $this->keyParametersByArgument(
$dependencies,$parameters
);
$instances = $this->getDependencies(
$dependencies,$parameters
);
array_pop($this->buildStack);
return $reflector->newInstanceArgs($instances);
}
具体从容器中获取实例的办法:PHP编程
protected function resolveClass(ReflectionParameter $parameter)
{
try {
return $this->make($parameter->getClass()->name);
}
// If we can not resolve the class instance,we will check to see if the value
// is optional,and if it is we will return the optional parameter value as
// the value of the dependency,similarly to how we do this with scalars.
catch (BindingResolutionContractException $e) {
if ($parameter->isOptional()) {
return $parameter->getDefaultValue();
}
throw $e;
}
}
框架底层通过Reflection反射为开发节省了很多细节,实现了自动依赖注入.这里不做继续深入研究了.PHP编程 写了一个模拟这个过程的类测试:PHP编程
<?php
class kulou
{
//
}
class junjun
{
//
}
class tanteng
{
private $kulou;
private $junjun;
public function __construct(kulou $kulou,junjun $junjun)
{
$this->kulou = $kulou;
$this->junjun = $junjun;
}
}
//$tanteng = new tanteng(new kulou(),new junjun());
$reflector = new ReflectionClass('tanteng');
$constructor = $reflector->getConstructor();
$dependencies = $constructor->getParameters();
print_r($dependencies);exit;
原理是通过ReflectionClass类解析类的构造函数,并且取出构造函数的参数,从而判断依赖关系,从容器中取,并自动注入.PHP编程 转自:小谈博客 http://www.tantengvip.com/2016/01/laravel-construct-ioc/PHP编程 更多关于Laravel相关内容感兴趣的读者可查看本站专题:《Laravel框架入门与进阶教程》、《php优秀开发框架总结》、《smarty模板入门基础教程》、《php日期与时间用法总结》、《php面向对象程序设计入门教程》、《php字符串(string)用法总结》、《php+mysql数据库操作入门教程》及《php常见数据库操作技巧汇总》PHP编程 希望本文所述对大家基于Laravel框架的PHP程序设计有所赞助.PHP编程 《:Laravel实现构造函数自动依赖注入的方法》是否对您有启发,欢迎查看更多与《:Laravel实现构造函数自动依赖注入的方法》相关教程,学精学透。编程之家 52php.cn为您提供精彩教程。 (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |

