Using PropertyPlaceholderConfigurer in servlet.xml

[rosco]

How can I use a PropertyPlaceholderConfigurer in the *-servlet.xml files? I want to replace certain controller implementation class names using the same properties file that the applicationContext.xml uses.

Can someone please advise?

Thanks

[ojolly]

In general, when you want to use a BeanFactoryPostProcessor in an ApplicationContext, you simply have to declare a bean of this type and it will be interpreted by the application context. The same applies to configuration of servlet, being a XmlWebApplicationContext.
However, you seems to be willing to change the class name. Afaik this is not interpreted by post processor, which can only change property content. You can have a try but I think it doesn't work.
In this case, you could imagine having beans which are in fact FactoryBean implementation and are configured with a property indicating the class name of the bean to create. Have a look at FactoryBean interface, it is really easy.

HTH

Olivier

[rosco]

Its not just the class name that I want to configure. I also have string properties on many of my controllers that I want to externalize into a .properties file using the PropertyPlaceholderConfigurer and the ${...} syntax. It works great in the applicationContext.xml file but it doesn't seem to work in the *-servlet.xml files.

[ojolly]

There's nothing which could explain why it works in applicationContext-xml and not *-servlet.xml. Can you turn on log on level debug and dump the result ?
By "not working", I assume the properties are valued to "${....}" instead of the property value and that you don't have exception, right ?

Olivier

[rosco]

Olivier,

Thanks for your help. I spoke too soon, it does replace values correctly, but not the class="" attribute of a bean definition. You were 100% correct in your previous post.

My course of action at this point is to define 2 controllers and use the property placeholder to point my url mapping to the correct controller:


<prop key="/entry.html">${entry.controller}</prop>

Then in the .properties file I will have either:

entry.controller=devEntryController OR entry.controller=prodEntryController

depending on my build script.

Thanks again for your help.

[Jon Chase]

Ok, if PropertyPlaceHolderConfigurer is supposed to work in the *-servlet.xml files, I must be doing something wrong, as I can't seem to get it to work (properties resolve to "${blah}" and not their real values).


Here's my web.xml:

 <context-param>
  <param-name>contextConfigLocation</param-name>
   <param-value>
    /WEB-INF/classes/applicationContext.xml
    /WEB-INF/classes/otherContext.xml
   </param-value>
 </context-param>

...

 <servlet>
  <servlet-name>context</servlet-name>
  <servlet-class>org.springframework.web.context.ContextLoaderServlet</servlet-class>
  <load-on-startup>1</load-on-startup>
 </servlet>

...

 <servlet>
  <servlet-name>ia</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <load-on-startup>2</load-on-startup>
 </servlet>

And here's the applicationContext.xml file:

...
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
 <property name="locations">
  <list>
   <value>classpath:/darwinia.properties</value>
  </list>
 </property>
</bean>
...

And finally, here's my ia-servlet.xml file:

 <bean id="helloWorldController" class="ia.web.controller.HelloWorldController">
    <property name="displayTranscriptLink"><value>${ia.displayLink}</value></property>
 </bean>

So, instead of ${ia.displayLink} resolving to "true" (or whatever is in the properties file), it resolves to "${ia.displayLink}".

Now, I should mention, the PropertyPlaceHolderConfigurer DOES work for me in other (non *-servlet.xml) context files; i.e. other context files under WEB-INF/classes (like otherContext.xml defined in web.xml above).

I can also see, on application startup in the log output, that the parent context of the ia-servlet context is the root application context (i.e. I can see that the parent context of ia-servlet contains the PropertyPlaceHolderConfigurer definition).

What in the world am I missing?

Jon

[Lawrence Ho]

You have shown part of your ia-servlet.xml, which does not contain any definition of PropertyPlaceholderConfigurer. Have you tried to define a separate PropertyPlaceholderConfigurer for your ia-servlet context?

Lawrence

[Jon Chase]

No, I've got the PropertyPlaceHolderConfigurer defined in my root applicationContext.xml file (along with many other beans). I have access to the other beans defined in the root context, so I don't need to declare PropertyPlaceHolderConfigurer in ia-servlet.xml.

[magnusheino]

Did anyone come up with a solution to this problem?

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.Pr opertyPlaceholderConfigurer">
<property name="location">
<value>/WEB-INF/bryggan.properties</value>
</property>
</bean>

I can replace variables defined using this bean declaration in everything but *-servlet.xml files.

[magnusheino]

Adding the answer from Jurgen on the spring-dev list as referernce for others that might search the forums later on.

PropertyPlaceholderConfigurer is an implementation of the
BeanFactoryPostProcessor interface: This interface and its sibling
BeanPostProcessor just apply to the BeanFactory that defines them, that is,
to the application context that defines them.

If you combine multiple config files into a single contextConfigLocation, a
PropertyPlaceholderConfigurer defined in any of the files will apply to all
of the files, because they are loaded into a single application context.

However, a DispatcherServlet has its own application context, just using the
root web application context as parent. Therefore, it needs to define its
own BeanFactoryPostProcessors and/or BeanPostProcessors, in this case its
own PropertyPlaceholderConfigurer.

I believe that this is the better general solution: Each application context
might want to resolve its placeholders against its own properties files,
where applying PropertyPlaceholderConfigurer from parent contexts would
interfere.

Juergen