实现与弹簧3注释简单工厂模式 [英] Implement a simple factory pattern with Spring 3 annotations

问题描述

我想知道我怎么能实现与Spring 3注解简单工厂模式。我说，你可以创建调用工厂类和经营的工厂方法豆的文档中看到的。我在想，如果这是可能的使用注释只。

I was wondering how I could implement the simple factory pattern with Spring 3 annotations. I saw in the documentation that you can create beans that call the factory class and run a factory method. I was wondering if this was possible using annotations only.

我有当前通话

MyService myService = myServiceFactory.getMyService(test);
result = myService.checkStatus();

为MyService是一个方法接口叫的checkStatus（）。

MyService is an interface with one method called checkStatus().

我的工厂类看起来是这样的：

My factory class looks like this:

@Component
public class MyServiceFactory {

    public static MyService getMyService(String service) {
        MyService myService;

        service = service.toLowerCase();

        if (service.equals("one")) {
            myService = new MyServiceOne();
        } else if (service.equals("two")) {
            myService = new MyServiceTwo();
        } else if (service.equals("three")) {
            myService = new MyServiceThree();
        } else {
            myService = new MyServiceDefault();
        }

        return myService;
    }
}

MyServiceOne类看起来是这样的：

MyServiceOne class looks like this :

@Autowired
private LocationService locationService;

public boolean checkStatus() {
      //do stuff
}

当我运行这个code中的locationService变量是alwasy空。我beleive这是因为我创建的对象自己在工厂里面，并自动连接没有发生。有没有办法添加注释正确地使这项工作？

When I run this code the locationService variable is alwasy null. I beleive this is because I am creating the objects myself inside the factory and autowiring is not taking place. Is there a way to add annotations to make this work correctly?

感谢

推荐答案

您是对的，通过创建对象手动你是不是让Spring来自动装配执行。考虑由Spring管理服务的，以及：

You are right, by creating object manually you are not letting Spring to perform autowiring. Consider managing your services by Spring as well:

@Component
public class MyServiceFactory {

    @Autowired
    private MyServiceOne myServiceOne;

    @Autowired
    private MyServiceTwo myServiceTwo;

    @Autowired
    private MyServiceThree myServiceThree;

    @Autowired
    private MyServiceDefault myServiceDefault;

    public static MyService getMyService(String service) {
        service = service.toLowerCase();

        if (service.equals("one")) {
            return myServiceOne;
        } else if (service.equals("two")) {
            return myServiceTwo;
        } else if (service.equals("three")) {
            return myServiceThree;
        } else {
            return myServiceDefault;
        }
    }
}

不过，我会考虑的整体设计是相当差。岂不更好有一个一般为MyService 执行情况，并通过有一个 / 两个 / 三字符串作为额外的参数的checkStatus（）？你想要什么来实现？

But I would consider the overall design to be rather poor. Wouldn't it better to have one general MyService implementation and pass one/two/three string as extra parameter to checkStatus()? What do you want to achieve?

@Component
public class MyServiceAdapter implements MyService {

    @Autowired
    private MyServiceOne myServiceOne;

    @Autowired
    private MyServiceTwo myServiceTwo;

    @Autowired
    private MyServiceThree myServiceThree;

    @Autowired
    private MyServiceDefault myServiceDefault;

    public boolean checkStatus(String service) {
        service = service.toLowerCase();

        if (service.equals("one")) {
            return myServiceOne.checkStatus();
        } else if (service.equals("two")) {
            return myServiceTwo.checkStatus();
        } else if (service.equals("three")) {
            return myServiceThree.checkStatus();
        } else {
            return myServiceDefault.checkStatus();
        }
    }
}

这是的仍然设计不当，因为添加新的为MyService 的实施需要 MyServiceAdapter 修改为以及（SRP违例）。但其实这是一个很好的起点。（提示：地图和策略模式）

This is still poorly designed because adding new MyService implementation requires MyServiceAdapter modification as well (SRP violation). But this is actually a good starting point (hint: map and Strategy pattern).

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