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问题描述

我在这里有类似的问题

,其中包含针对Guice的解决方案。

with a solution for Guice.

但是我有一个使用spring di(beans)的项目,但是有同样的问题。

But I have a different project using spring di (beans), but with the same kind of issue.

I具有N个混凝土的界面。 (此处为3)

I have an interface with N number of concretes. (3 here)

public interface OrderProcessorInterface {

  void ProcessOrder(String preferredShipperAbbreviation, Order ord);

}

public class FedExShipper implements ShipperInterface {

  private Log logger;

  public FedExShipper(Log lgr) {

    if (null == lgr) {
      throw new IllegalArgumentException("Log is null");
    }

    this.logger = lgr;
  }

  public void ShipOrder(Order ord) {
    this.logger.info("I'm shipping the Order with FexEx");
  }
}


public class UpsShipper implements ShipperInterface {

  private Log logger;

  public UpsShipper(Log lgr) {

    if (null == lgr) {
      throw new IllegalArgumentException("Log is null");
    }

    this.logger = lgr;
  }

  public void ShipOrder(Order ord) {
    this.logger.info("I'm shipping the Order with Ups");
  }
}


public class UspsShipper implements ShipperInterface {

  private Log logger;

  public UspsShipper(Log lgr) {

    if (null == lgr) {
      throw new IllegalArgumentException("Log is null");
    }

    this.logger = lgr;
  }

  public void ShipOrder(Order ord) {
    this.logger.info("I'm shipping the Order with Usps");
  }
}

...

然后我有一堂课,需要了解所有三种混凝土。

Then I have a class that needs to know about ALL THREE concretes.

import java.util.Collection;
import java.util.Set;

import org.apache.commons.logging.Log;

public class OrderProcessorImpl implements OrderProcessorInterface {

  private Log logger;
  private java.util.Map<String, javax.inject.Provider<ShipperInterface>> shipperProviderMap;

  public OrderProcessorImpl(Log lgr, java.util.Map<String, javax.inject.Provider<ShipperInterface>> spMap) {

    if (null == lgr) {
      throw new IllegalArgumentException("Log is null");
    }

    if (null == spMap) {
      throw new IllegalArgumentException("Provider<ShipperInterface> is null");
    }

    this.logger = lgr;
    this.shipperProviderMap = spMap;
  }

  public void ProcessOrder(String preferredShipperAbbreviation, Order ord) {
    this.logger.info(String.format("About to ship. (%1s)", preferredShipperAbbreviation));


    ShipperInterface foundShipperInterface = this.FindShipperInterface(preferredShipperAbbreviation);
    foundShipperInterface.ShipOrder(ord);
  }

  private ShipperInterface FindShipperInterface(String preferredShipperAbbreviation) {

    ShipperInterface foundShipperInterface = this.shipperProviderMap.get(preferredShipperAbbreviation).get();

    if (null == foundShipperInterface) {
      throw new NullPointerException(
          String.format("ShipperInterface not found in shipperProviderMap. ('%1s')", preferredShipperAbbreviation));
    }

    return foundShipperInterface;
  }
}

=========== ==

=============

基本上,我想调用该方法,传入一个字符串参数,然后让它为我选择具体的方法。 (如果是我的真实代码,这是通过数据库值实现的,但是对于演示代码来说,这已经足够了)

Basically, I want to call the method, pass in a string argument, and have it choose the concrete for me. (if my real code, this is via a database value, but for the demo code, this is good enough)

Order ord = new Order();
ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");
BeanFactory factory = context;

OrderProcessorInterface opi = context.getBean(OrderProcessorImpl.class);
opi.ProcessOrder("myFedExName", ord); /* friendlyName would be nice, but fully qualified concrete name also assceptable */

我的Spring配置通过xml:

My Spring Configuration is via xml:

 <bean id="theLoggerBean"
       class="org.apache.commons.logging.impl.Log4JLogger">
       <constructor-arg value="log" />
 </bean>



<bean id="fedExBean"
    class="com.me.FedExShipper">
    <constructor-arg ref="theLoggerBean"></constructor-arg>
</bean>


<bean id="uspsExBean"
    class="com.me.FedExShipper">
    <constructor-arg ref="theLoggerBean"></constructor-arg>
</bean>


<bean id="upsExBean"
    class="com.me.FedExShipper">
    <constructor-arg ref="theLoggerBean"></constructor-arg>
</bean>

..........

..........

===============================

================================

<bean id="OrderProcessorImplBean"
    class="com.me.OrderProcessorImpl">

    <constructor-arg ref="theLoggerBean"></constructor-arg>

    <constructor-arg ref="How do I do N Number of ShipperInterfaces Here ??"></constructor-arg>

</bean>

所以我想通过xml配置这3种具体情况。

So I want to xml configure the 3 concretes.

然后将它们注入到类中。

And then inject them into the class.

但是在我有我该怎么办N个ShipperInterfaces吗??的地方,我不知道该怎么办。

But where I have "How do I do N Number of ShipperInterfaces Here ??", I have no idea what to do.

首选JSR 330实施,但是会花费很多。

JSR 330 implementation preferred, but will take anything.

谢谢

请注意,在另一个问题(Guice问题)中,这也可能OrderProcessor的构造函数:

Note, in the other question (the Guice one), this was also a possiblity for the constructor of the OrderProcessor:

public class OrderProcessorImpl implements OrderProcessorInterface {

  private Log logger;
  Set<ShipperInterface> shippers;

  public OrderProcessorImpl(Log lgr, Set<ShipperInterface> shprs) {

    if (null == lgr) {
      throw new IllegalArgumentException("Log is null");
    }

    if (null == shprs) {
      throw new IllegalArgumentException("ShipperInterface(s) is null");
    }

    this.logger = lgr;
    this.shippers = shprs;
  }

  public void ProcessOrder(String preferredShipperAbbreviation, Order ord) {
    this.logger.info(String.format("About to ship. (%1s)", preferredShipperAbbreviation));

    for (ShipperInterface sh : shippers) {
      this.logger.info(String.format("ShipperInterface . (%1s)", sh.getClass().getSimpleName()));
    }

  }
}


推荐答案

类似的事情应该起作用。这使用@Autowired而不是xml配置:

Something like this should work. This uses @Autowired and not xml configuration:

@org.springframework.stereotype.Service
public class OrderProcessorImpl implements OrderProcessorInterface {

    private List<ShipperInterface> shipperProviders;

    private Map<String, ShipperInterface> shipperProvidersMap = new HashMap<>();

    @Autowired
    public void setShipperProviders(List<ShipperInterface> shipperProviders) {
        this.shipperProviders= shipperProviders;

        this.shipperProviders.stream().forEach(p->shipperProvidersMap .put(/* your code for getting the key */, p));
    }

等级依赖提示:

compile group: 'org.springframework', name: 'spring-context', version: '5.1.9.RELEASE'

这篇关于带有多种混凝土的Spring DI(Beans)...选择其中之一的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

08-18 18:18