How to achieve conditional resource import in a Spring XML context?

Question

What I would like to achieve is the ability to "dynamically" (i.e. based on a property defined in a configuration file) enable/disable the importing of a child Spr

Answer 1

Another option is to have your app load a modules-config.xml file that is located in the /conf folder and edit it during the install/config phase to uncomment the modules you want loaded.

This is the solution I'm using with a web application that serves as a container for different integration modules. The web application is distributed with all the different integration modules. A modules-config.xml is placed in tomcat's /conf folder and the conf folder is added to the classpath (via catalina.properties/common.loader property). My web app webapp-config.xml has a <import resource="classpath:/modules-config.xml"/> to get it loaded.

Answer 2

You can override contextInitialized(javax.servlet.ServletContextEvent event) in your own ContextLoaderListener and set required System property before super.contextInitialized(event) called like this

package com.mypackage;
import org.springframework.web.context.ContextLoaderListener;
public class MyContextLoaderListener extends ContextLoaderListener {
    public void contextInitialized(javax.servlet.ServletContextEvent event) {
        System.setProperty("xyz", "import-file-name.xml");
        super.contextInitialized(event);
    }
}

And than replace ContextLoaderListener to MyContextLoaderListener in your web.xml

<listener>
    <listener-class>com.mypackage.MyContextLoaderListener</listener-class>
</listener>

Now you can use in your spring.xml

<import resource="${xyz}" /> 

I hope this will help.

Answer 3

Another one to consider for Spring 3.0:

 <alias name="Whatever" alias=""Whatever-${yyzzy}" />

where ${xyzzy} interpolates a property from the system properties.

Answer 4

As mentioned earlier, this can be easily accomplished with profiles if you're using Spring 3.1+

<!-- default configuration - will be loaded if no profile is specified -->
<!-- This will only work if it's put at the end of the configuration file -->
<!-- so no bean definitions after that -->
<beans profile="default">
    <import resource="classpath:default.xml" />
</beans>
<!-- some other profile -->
<beans profile="otherProfile">
    <import resource="classpath:other-profile.xml" />
</beans>

otherProfile can be easily activated with e.g.

mvn install -Dspring.profiles.active=otherProfile

if you're using different profiles in tests, just add -DforkMode=never to make sure that the tests will run inside same VM, therefore the param spring.profiles.active wont be lost

Answer 5

With Spring 3.1.x you can use bean profiles to achieve conditional resource import and bean instantiation. This is of course of no help if you are using an earlier version :)

Answer 6

This is now completely possible, using Spring 4.

In your main application content file

<bean class="com.example.MyConditionalConfiguration"/>

And the MyConditionalConfiguration looks like

@Configuration
@Conditional(MyConditionalConfiguration.Condition.class)
@ImportResource("/com/example/context-fragment.xml")
public class MyConditionalConfiguration {
    static class Condition implements ConfigurationCondition {
         @Override
         public ConfigurationPhase getConfigurationPhase() {
             return ConfigurationPhase.PARSE_CONFIGURATION;
         }
         @Override
         public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
             // only load context-fragment.xml if the system property is defined
             return System.getProperty("com.example.context-fragment") != null;
         }
    }
}

And then finally, you put the bean definitions you want included in the /com/example/context-fragment.xml

See the JavaDoc for @Conditional