PHP依赖倒置(Dependency Injection)代码实例

public function set($abstract,$concrete = null)
{
if ($concrete === null) {
$concrete = $abstract;
}

$this->setings[$abstract] = $concrete;
}

public function get($abstract,$parameters = array())
{
if (!isset($this->setings[$abstract])) {
return null;
}

return $this->build($this->setings[$abstract],$parameters);
}

public function build($concrete,$parameters)
{
if ($concrete instanceof Closure) {
return $concrete($this,$parameters);
}

$reflector = new ReflectionClass($concrete);

if (!$reflector->isInstantiable()) {
throw new Exception("Class {$concrete} is not instantiable");
}

$constructor = $reflector->getConstructor();

if (is_null($constructor)) {
return $reflector->newInstance();
}

$parameters = $constructor->getParameters();
$dependencies = $this->getDependencies($parameters);

return $reflector->newInstanceArgs($dependencies);
}

public function getDependencies($parameters)
{
$dependencies = array();
foreach ($parameters as $parameter) {
$dependency = $parameter->getClass();
if ($dependency === null) {
if ($parameter->isDefaultValueAvailable()) {
$dependencies[] = $parameter->getDefaultValue();
} else {
throw new Exception("Can not be resolve class dependency {$parameter->name}");
}
} else {
$dependencies[] = $this->get($dependency->name);
}
}

return $dependencies;
}
}

interface MyInterface{}
class Foo implements MyInterface{}
class Bar implements MyInterface{}
class Baz
{
public function __construct(MyInterface $foo)
{
$this->foo = $foo;
}
}

$container = new Container();
$container->set('Baz','Baz');
$container->set('MyInterface','Foo');
$baz = $container->get('Baz');
print_r($baz);
$container->set('MyInterface','Bar');
$baz = $container->get('Baz');
print_r($baz);