CODEWITHSUNDEEP
javaspringsingleton
user1269701
user1269701

Reputation: 135

factory method pattern in java

Is it a good practice to have objects specific to some implementation as member variables in a factory class ? For e.g., in the code below, s1 and s2 are required for constructing OneChannel and secondChannel objects respectively. Is it a good practice to declare these as member variables inside the factory ? If not, what can e the other alternative. 

public class CommunicationChannelFactoryImpl {
@Autowired 
SomeClass s1;
@Autowired
SomeOtherClass s2;

 public CommunicationChannel getCommunicationChannel(String channel, Map<String, String> channelProperties) {

  if(channel.equals("ONE")   {
    return new OneChannel(s1);
  }

  if(channel.equals("TWO") {
   return new SecondChannel(s2);
  }
 }
}

Please note that s1 ad s2 are singleton beans

Upvotes: 1

Views: 93

Answers (2)

Luca Basso Ricci
Luca Basso Ricci

Reputation: 18423

Why don't let Spring create OneChannel() and SecondChannel() object using BeanFactoryAware?

public class CommunicationChannelFactoryImpl implements BeanFactoryAware {
  FactoryBean factoryBean;

  public void setBeanFactory(FactoryBean factoryBean) {
    this.factoryBean = factoryBean;
  }
  public CommunicationChannel getCommunicationChannel(String channel, Map<String, String> channelProperties) {

    if(channel.equals("ONE")   {
      return this.factoryBean.getBean("oneChannel");
    }

    if(channel.equals("TWO") {
      return this.factoryBean.getBean("secondChannel");
    }
  }
}

and define your XML (or JavaConfig, but I'm not using it) as:

<bean id="oneChannel" scope="prototype">
  <constructor-arg index="0" ref="s1" />
</bean>
<bean id="secondChannel" scope="prototype">
  <constructor-arg index="0" ref="s2" />
</bean>
<bean id="s1" class="path.to.SomeClass" />
<bean id="s2" class="path.to.SomeOtherClass" />

Upvotes: 0

MD Sayem Ahmed
MD Sayem Ahmed

Reputation: 29186

Since you need those beans for constructing those particular channel implementations, I think you can keep them as properties in that particular factory implementation. You are injecting the required components, so you have the flexibility to change the implementations later if you need.

Also, it will be better if SomeClass and SomeOtherClass are some abstractions/interfaces/super type. In this way if you ever need to provide different implementations for building those channel objects in the future, you'll be able to do so pretty easily.

Upvotes: 1

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