laravel框架中容器类简化代码-摘自某书

  1 <?php 
  2 
  3 //容器类装实例或提供实例的回调函数
  4 class Container {
  5 
  6     protected $bindings = [];
  7 
  8     //绑定接口和生成相应实例的回调函数
  9     public function bind($abstract, $concrete=null, $shared=false) {
 10         
 11         //如果提供的参数不是回调函数，则产生默认的回调函数
 12         if(!$concrete instanceof Closure) {
 13             $concrete = $this->getClosure($abstract, $concrete);
 14         }
 15         
 16         $this->bindings[$abstract] = compact(‘concrete‘, ‘shared‘);
 17     }
 18 
 19     //默认生成实例的回调函数
 20     protected function getClosure($abstract, $concrete) {
 21         
 22         return function($c) use ($abstract, $concrete) {
 23             $method = ($abstract == $concrete) ? ‘build‘ : ‘make‘;
 24             return $c->$method($concrete);
 25         };
 26         
 27     }
 28 
 29     public function make($abstract) {
 30         $concrete = $this->getConcrete($abstract);
 31 
 32         if($this->isBuildable($concrete, $abstract)) {
 33             $object = $this->build($concrete);
 34         } else {
 35             $object = $this->make($concrete);
 36         }
 37         
 38         return $object;
 39     }
 40 
 41     protected function isBuildable($concrete, $abstract) {
 42         return $concrete === $abstract || $concrete instanceof Closure;
 43     }
 44 
 45     //获取绑定的回调函数
 46     protected function getConcrete($abstract) {
 47         if(!isset($this->bindings[$abstract])) {
 48             return $abstract;
 49         }
 50 
 51         return $this->bindings[$abstract][‘concrete‘];
 52     }
 53 
 54     //实例化对象
 55     public function build($concrete) {
 56 
 57         if($concrete instanceof Closure) {
 58             return $concrete($this);
 59         }
 60 
 61         $reflector = new ReflectionClass($concrete);
 62         if(!$reflector->isInstantiable()) {
 63             echo $message = "Target [$concrete] is not instantiable";
 64         }
 65 
 66         $constructor = $reflector->getConstructor();
 67         if(is_null($constructor)) {
 68             return new $concrete;
 69         }
 70 
 71         $dependencies = $constructor->getParameters();
 72         $instances = $this->getDependencies($dependencies);
 73 
 74         return $reflector->newInstanceArgs($instances);
 75     }
 76 
 77     //解决通过反射机制实例化对象时的依赖
 78     protected function getDependencies($parameters) {
 79         $dependencies = [];
 80         foreach($parameters as $parameter) {
 81             $dependency = $parameter->getClass();
 82             if(is_null($dependency)) {
 83                 $dependencies[] = NULL;
 84             } else {
 85                 $dependencies[] = $this->resolveClass($parameter);
 86             }
 87         }
 88 
 89         return (array)$dependencies;
 90     }
 91 
 92     protected function resolveClass(ReflectionParameter $parameter) {
 93         return $this->make($parameter->getClass()->name);
 94     }
 95 
 96 }
 97 
 98 
 99 class Traveller {
100 
101     protected $trafficTool;
102 
103     public function __construct(Visit $trafficTool) {
104         $this->trafficTool = $trafficTool;
105     }
106 
107     public function visitTibet() {
108         $this->trafficTool->go();
109     }
110 
111 }
112 
113 interface Visit {
114     public function go();
115 }
116 
117 class Train implements Visit {
118 
119     public function go() {
120         echo "go to Tibet by train !!!";
121     }
122     
123 }
124 
125 $app = new Container();
126 $app->bind("Visit", "Train");
127 $app->bind("traveller", "Traveller");
128 
129 
130 $tra = $app->make("traveller");
131 $tra->visitTibet();