Liferay’s MVC framework lets you split your portlet’s action methods into separate classes. This can be very helpful in portlets that have many actions. Each action URL in your portlet’s JSPs then calls the appropriate action class when necessary.
First, use the <portlet:actionURL> tag to create the action URL in your JSP.
For example, the edit blog entry action in Liferay’s Blogs app is defined in the
edit_entry.jsp file
as follows:
<portlet:actionURL name="/blogs/edit_entry" var="editEntryURL" />
When the action URL is triggered, the matching action class processes the
action. Implement the action by creating a class that implements the
MVCActionCommand
interface.
To avoid writing oodles of boilerplate code, your *MVCActionCommand class
should extend the BaseMVCActionCommand
class
instead of implementing MVCActionCommand directly. The BaseMVCActionCommand
class already implements MVCActionCommand and provides many useful method
implementations. Naming your *MVCActionCommand class after the action it
performs is a good convention. For example, if your action edits some kind of
entry, you could name its class EditEntryMVCActionCommand.
Your *MVCActionCommand class must also have a @Component annotation like the
following. Set the property javax.portlet.name to your portlet’s internal
ID, and the property mvc.command.name to the value of the name property in
your JSP’s matching actionURL. To register the component in the OSGi container
as using the MVCActionCommand class, you must set the service property to
MVCActionCommand.class:
@Component(
immediate = true,
property = {
"javax.portlet.name=your_portlet_name_YourPortlet",
"mvc.command.name=/your/jsp/action/url"
},
service = MVCActionCommand.class
)
public class YourMVCActionCommand extends BaseMVCActionCommand {
// implement your action
}
For example, this is the @Component annotation for the Blogs app’s
EditEntryMVCActionCommand class:
@Component(
immediate = true,
property = {
"javax.portlet.name=" + BlogsPortletKeys.BLOGS,
"javax.portlet.name=" + BlogsPortletKeys.BLOGS_ADMIN,
"javax.portlet.name=" + BlogsPortletKeys.BLOGS_AGGREGATOR,
"mvc.command.name=/blogs/edit_entry"
},
service = MVCActionCommand.class
)
public class EditEntryMVCActionCommand extends BaseMVCActionCommand {
// the app's edit blog entry action implementation
}
Note that you can use multiple javax.portlet.name values to indicate the
component works with multiple portlets.
In your *MVCActionCommand class, process the action by overriding the
BaseMVCActionCommand class’s
doProcessAction method.
This method takes javax.portlet.ActionRequest and javax.portlet.ActionResponse parameters that you can
use to process your action. Your *MVCActionCommand class should also contain
any other code required to implement your action. For a real-world example of a
*MVCActionCommand class, see the Blogs app’s EditEntryMVCActionCommand
class.