Create a soap ui mock project with Java

I'm working on a project where I need to mock the application backend. What I want to know is that if I can intercept the requests and responses in my project, can I write them in a xml file the same way soapui does? Does anyone have experience doing so?

I'm logging all the requests and responses to a file right now. I'm trying to figure out how soap ui stores the mock responses in xml format.