Using Spring

If you love the Spring Framework and the Model-View-Controller (MVC) pattern, you can develop portlets using PortletMVC4Spring. If you use this framework, you may already be familiar with developing servlet-based web applications using Spring Web MVC. PortletMVC4Spring is for developing portlet-based applications using MVC. You can build Spring Framework Liferay portlets with features like these:

• Inversion of control (IoC) / dependency injection (DI)
• Annotations
• Security
• Binding and validation
• Multi-part file upload
• … and more

Here are the topics about PortletMVC4Spring:

• Developing a Portlet Using PortletMVC4Spring: Demonstrates creating and deploying a portlet using PortletMVC4Spring.

• Annotation-based Controller Development: Shows how to implement controllers using plain old Java objects (POJOs) and annotations.

Background

The PortletMVC4Spring project began as Spring Portlet MVC and was part of the Spring Framework. When the project was pruned from version 5.0.x of the Spring Framework under SPR-14129, it became necessary to fork and rename the project. This made it possible to improve and maintain the project for compatibility with the latest versions of the Spring Framework and the Portlet API.

Liferay adopted Spring Portlet MVC in March of 2019, and renamed the project to PortletMVC4Spring.

Spring Web MVC is similar to PortletMVC4Spring, but is adapted to portlets. Portlet workflow differs from servlet workflow because a request to the portlet can have two distinct phases: the ACTION_PHASE and the RENDER_PHASE. The ACTION_PHASE is executed only once and triggers backend changes or actions, like database operations. The RENDER_PHASE presents the portlet’s content to the user each time the display is refreshed. Thus for a single request, the ACTION_PHASE is executed only once, but the RENDER_PHASE may be executed multiple times. This provides (and requires) a clean separation between the activities that modify the system’s persistent state and the activities that generate content. The Portlet 2.0 Specification added two more phases: The event phase and the resource phase, both of which are supported by annotation-driven dispatching.

PortletMVC4Spring provides annotations that support requests from the render, action, event, and resource-serving portlet phases; Spring Web MVC provides only a @RequestMapping annotation. Where a Spring Web MVC controller might have a single handler method annotated with @RequestMapping, an equivalent PortletMVC4Spring controller might have multiple handler methods, each using one of the phase annotations: @ActionMapping, @EventMapping, @RenderMapping, or @ResourceMapping.

The PortletMVC4Spring framework uses a DispatcherPortlet that dispatches requests to handlers, with configurable handler mappings and view resolution, like the DispatcherServlet in the web framework.

Note

For more information on portlets, portlet specifications, and how portlets differ from servlets, see Portlets.

Liferay also provides full-featured sample portlets that demonstrate using JSP and Thymeleaf view templates. They exercise many features that form-based portlet applications typically require.

The samples are available here:

Source Code	Maven Central
applicant-jsp-portlet	com.liferay.portletmvc4spring.demo.applicant.jsp.portlet.war
applicant-thymeleaf-portlet	com.liferay.portletmvc4spring.demo.applicant.thymeleaf.portlet.war

Now that you have a basic understanding of PortletMVC4Spring portlets and how they compare to Spring Web MVC applications, it’s time to develop a PortletMVC4Spring portlet.