Injecting beans of a jar from another component/app

[Akhilesh Trivedi]

My question is pertaining to this thread.

https://coderanch.com/t/652792/Spring/Spring-Jar-giving-null-pointer


When we create a Spring Jar and it is consumed by another component/app, how do we initialize/inject the depencies of the included jar, do we need to know the name of the spring xml file and include that as well in our new component/app's xml file?

[Jayesh A Lalwani]

There are 4 ways you can do this

1) do not include spring xml files in your jar. Your client can have his own spring xml to ok instantiate your classes. You are making your work simple. You are putting work on your clients

2) include a spring xml in your jar that your client can import. From a spring xml, you can import other spring xmls. As long as the imported xml is in classpath, spring can import it. This way you reduce work for your client, but you force them to use spring. Also you lose flexibility.

3) implement a namespace handler.
Using a namespace handler you can have your namespace with custom xml tags. When the client uses your custom tag, your namespace handler is invoked when the xml is parsed. Your namespace handler can programmatically add bean definition to the factory. This option is very complicated for you, but is the most flexible.

4) completely hide the bean factory. You can put your spring xml inside your jar. Also inside your jar put a Singleton class that wraps the bean factory. Your client can call this singleton class to get the beans.