Laravel实现构造函数自动依赖注入的方法 本文实例讲述了Laravel实现构造函数自动依赖注入的方法。分享给大家供大家参考,具体如下: 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: 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。 源码vendor/illuminate/container/Container.php中的build方法: $constructor = $reflector->getConstructor(); dump($constructor); 这里会解析类的构造函数,在这里打印看: 它会找出构造函数的参数,再看完整的build方法进行的操作: 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方法: 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。 写了一个模拟这个过程的类测试: 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。 转自:小谈博客 http://www.tantengvip.com/2016/01/laravel-construct-ioc/ 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》 希望本文所述对大家基于Laravel框架的PHP程序设计有所帮助。