Check out the Core Spring documentation, it shows how to integrate with Struts, although I know for Struts 1, but not sure about Struts2/WebWorks(I forgot the real name of the product that changed their name to Struts 2)
Also
That's why I wanna use ClassPathXmlApplicationContext,
but it only allows me to load applicationContext.xml from classpath.
You can load from anywhere, not just ClassPath. Just prefix your location with file: or http: and you can access it by file location, or from within your WEB-INF directory.
Mark