Passing runtime known vaues to constructor called by Spring

I am creating an instance of an object (third party so I cant change it) who's constructor takes an IP address that isnt known until runtime. So I dont/cant hardcode the IP address into a spring config file.

So how can I ut开发者_JAVA百科ilize spring to create an instance of this class, when the value of one of its arguments isnt known until runtime?

You can use a config file, using the util namespace:

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:util="http://www.springframework.org/schema/util"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
       http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-2.0.xsd">
   ...
   <bean id="baseObject" class="...">
      <constructor-arg>
          <util:property-path path="propertyReader.runtimePropertyValue"/>
      </constructor-arg>
   </bean>

   <bean id="propertyReader" class="PropertyReader"/>
   ...
</beans>

Then in Java you would have

public class PropertyReader {
   ...
   public String getRuntimePropertyValue() {
       // Retrieve and return property value
   }     
   ...
}

As you can see, value injection is done automatically by Spring. You just need to implement a PropertyReader (class name not significant) that provides the injected values.