Main concepts
Spring facet, filesets, model
How do I...
Spring Model
Obtain Spring Model by file, PsiElement, ..
See SpringManager#getSpringModel(s)...
Contribute implicit model(s)
See com.intellij.spring.SpringModelProvider.
Contribute implicit beans
See com.intellij.spring.model.jam.CustomComponentsDiscoverer to provide implicit (framework-specific) beans (e.g. "servletContext" by Spring MVC).
XML Configuration
Add support for additional Spring namespace
See EP com.intellij.spring.dom.SpringCustomNamespaces, registered namespace-key must match the one registered with your DOM elements via @Namespace.
Code Configuration
IDE features
Add inspections to Spring Validator
Add additional inspections (e.g. for custom namespace) to Spring Validator via EP com.intellij.spring.SpringInspectionsRegistry$Contributor.
Configure Spring support for other frameworks
Use com.intellij.spring.facet.SpringConfigurator to provide "automatic" configuration when Spring facet is added via framework wizard.