在多战Spring应用程序中使用共享的父应用程序上下文

Question

I want to shared common application context in a multi-war Spring application, so i don't need to defined beans again and again. But i don't want to instantiate those beans defined in this common application context in each webapp . I only want to instantiate those beans once and share by all the webapps. Is it possible? Bare me if i'm wrong.

PS: this common application context exists in jar, which i'll import to every webapps.

1, Below article tell us how to share the common application context, but need to instantiate those beans in each webapp.

How to import spring-config.xml of one project into spring-config.xml of another project?

2, Below is another article i just read, i demo it, but still don't get what i want, beans got instantiated twice. Can someone check this section "Why would you want to use this?" in the article, i don't get it, do they have a solution there, can someone help me here, thanks a lot for your time.

http://spring.io/blog/2007/06/11/using-a-shared-parent-application-context-in-a-multi-war-spring-application/

here is the demo source code in second article: https://github.com/jasonluo/ceciic/tree/master/Research/multiple-contexts-sample

Updates

The problem of case2 is because i didn't deploy as a ear file, thanks Deinum for pointing this out, i'm using tomcat, so there is no way to achieve that.

Our solution now is using REST to access the service webapp which running in a separate server.

Answer 1

Don't, there is usually classloader isolation going on to prevent this. Doing this right usually requires a thorough understanding of classloading, Java EE, packaging and your server.

Having that said there is way to do this as outlined in the blog you posted. You have to:

• package both WARs into an EAR (this means you have to use and appserver like WildFly AS and can't just use a servlet engine like Tomcat or Jetty)
• package both WARs as "skinny" WARs with at least Spring (and all its dependencies) and the shared beans (and all their dependencies) in the lib/ folder of the EAR instead of the WEB-INF/lib folder of the WARs.

Even then it depends on implementation details of the server. AFAIK it is not guaranteed to work under the Java EE specification. For example it likely won't work in GlassFish.

Update

I can't tell if the output of your demo is correct because I couldn't find a build file.

Yes, Tomcat does not support EARs, you could use Apache TomEE which is very similar and supports EARs (I don't know if TomEE does classloading in a way that makes this work). In theory you could also make use of the common classloader in Tomcat but that would be quite a hack.

Answer 2

There is a way to do it, using Spring Dynamic Modules , but it requires OSGi environment, which is quite different from simple Tomcat. Few articles worth reading:

• Deploying Spring MVC applications to OSGi
• Hello world style example
• Blueprint - a further development on DM
• Another blueprint documentation reference to Spring

That being said there is not a lot of up to date information about Spring with OSGi, but it's worth a try to achieve just what you said (but of course, with additional performance cost)