Question

据我所知，有效模式是：

实例化所需服务的FooControllerFactory（FooService）
带有构造函数__construct（FooService $ fooService）
Controller获取一些基本数据并从服务中获取结果
服务包含所有必需的业务逻辑这是一项基本服务。最终，此服务将需要其他服务用于各种活动。例如CacheService，SomeOtherDataService。

问题是，什么是有效/适当的模式包括/注入其他相互关联的服务？

我们目前非常简化的reallife示例：

AuctionController

/**
  * get vehicles for specific auction
*/
public function getVehiclesAction ()
{
    $auctionService = $this->getAuctionService(); // via service locator
    $auctionID = (int) $this->params('auction-id');
    $auction = $auctionService->getAuctionVehicle($auctionID);
    return $auction->getVehicles();
}

AuctionService

public function getAuctionVehicles($auctionID) {
    $auction = $this->getAuction($auctionID);
    // verify auction (active, permissions, ...)
    if ($auction) {
        $vehicleService = $this->getVehicleService(); // via service locator
        $vehicleService->getVehicles($params); // $params = some various conditions or array of IDs
    }
    return false;
}

VehicleService

public function getVehicles($params) {
    $cache = $this->getCache(); // via service locator
    $vehicles = $cache->getItem($params);
    if (!$vehicles) {
        $vehicleDB = $this->getVehicleDB(); // via service locator
        $vehicles = $vehicleDB->getVehicles($params);
    }
    return $vehicles;
}

建议的有效模式示例

AuctionController

public function __construct(AuctionService $auctionService) {
    $this->auctionService = $auctionService;
}

/**
  * get vehicles for specific auction
*/
public function getVehiclesAction ()
{
    $auctionID = (int) $this->params('auction-id');
    $auction = $this->auctionService->getAuctionVehicle($auctionID);
    return $auction->getVehicles();
}
**AuctionService**

public function getAuctionVehicles($auctionID) {
    $auction = $this->getAuction($auctionID); // no problem, local function
    // verify auction (active, permissions, ...)
    if ($auction) {
        $vehicleService = $this->getVehicleService(); // we don't have service locator
        $vehicleService->getVehicles($params); // $params = some various conditions or array of IDs
    }
    return false;
}

VehicleService

public function getVehicles($params) {
    $cache = $this->getCache(); // we don't have service locator, but cache is probably static?
    $vehicles = $cache->getItem($params);
    if (!$vehicles) {
        $vehicleDB = $this->getVehicleDB(); // where and how do we get this service
        $vehicles = $vehicleDB->getVehicles($params);
    }
    return $vehicles;
}

一些注意事项：

服务仅在某些情况下相互关联，95％是独立服务
- 拍卖有很多功能，不需要车辆
- 车辆有VehicleController和VehicleService，只在某些情况下与拍卖有关，它是一个具有其他功能的独立模块
- 在控制器中注入所有需要的服务将浪费资源，因为在每个操作中都不需要它们（在现实生活中，我们有更多的互连服务，而不仅仅是两个）
在多个服务中编程相同的业务逻辑只是为了避免服务定位器显然是一种无效的模式，是不可接受的。

Answer 1

如果控制器需要太多不同的服务，通常会指示控制器有太多的责任。

跟进@ AlexP的回答，然后将此服务注入您的控制器。根据您的设置，当创建控制器时，这肯定会导致依赖注入级联。这至少会将创建的服务限制为控制器实际需要的服务（以及那些传递相关的服务）。

如果很少需要其中一些服务，并且您担心每次请求都创建它们，那么新的Service Manager现在也支持lazy services。那些仍然可以作为常规依赖项注入服务/控制器（如上所述），但仅在第一次调用时创建。

从文档示例中复制此内容：

$serviceManager = new \Zend\ServiceManager\ServiceManager([
    'factories' => [
        Buzzer::class             => InvokableFactory::class,
    ],
    'lazy_services' => [
         // Mapping services to their class names is required
         // since the ServiceManager is not a declarative DIC.
         'class_map' => [
             Buzzer::class => Buzzer::class,
         ],
    ],
    'delegators' => [
        Buzzer::class => [
            LazyServiceFactory::class,
        ],
    ],
]);

请求服务时，不会立即创建它：

$buzzer = $serviceManager->get(Buzzer::class);

但只有在第一次使用它时：

$buzzer->buz();

这样，您可以将多个依赖项注入控制器，并且只会创建实际需要的服务。当然，对于任何依赖都是如此，例如其他服务所需的服务等等。

Answer 2

您可以撰写一项新服务，比如VehicleAuctionService，并使用工厂将AuctionService和VehicleService注入为依赖项。

这是对象组合。

class VehicleAuctionService
{
    private $auctionService;
    private $vehicleService;

    public function __construct(
        AuctionService $auctionService, 
        VehicleService $vehicleService
    ){
        $this->auctionService = $auctionService;
        $this->vehicleService = $vehicleService;
    }

    public function getAuctionVehicles($auctionID)
    {
        $auction = $this->auctionService->getAuction($auctionID);

        if ($auction) {
            $params = [
                'foo' => 'bar',
            ];
            $this->vehicleService->getVehicles($params);
        }
        return false;
    }

}

用于互连服务的ZF3服务DI的有效模式

2 个答案: