PHP依赖倒置(Dependency Injection)代码实例

< php

class container
{
protected $setings = array();

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;
}
}

< php

require 'container.php';


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);