Configuring the View Layer

This section briefly covers how to get your view layer working, from organizing your imports in one JSP file, to creating URLs that direct processing to methods in your portlet class.

Note: As you create JSPs, you can apply Clay styles to your app to match Liferay’s apps.

Liferay’s best practice puts all Java imports, tag library declarations, and variable initializations into a JSP called init.jsp. If you use Blade CLI or Liferay Dev Studio DXP to create a module based on the mvc-portlet project template, these taglib declarations and initializations are added automatically to your init.jsp:

<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<%@ taglib uri="http://java.sun.com/portlet_2_0" prefix="portlet" %>

<%@ taglib uri="http://liferay.com/tld/aui" prefix="aui" %>
<%@ taglib uri="http://liferay.com/tld/portlet" prefix="liferay-portlet" %>
<%@ taglib uri="http://liferay.com/tld/theme" prefix="liferay-theme" %>
<%@ taglib uri="http://liferay.com/tld/ui" prefix="liferay-ui" %>

<liferay-theme:defineObjects />

<portlet:defineObjects />

Make sure to include the init.jsp in your other JSPs:

<%@include file="/html/init.jsp"%>

JSPs can use action URLs to invoke controller methods. To create a link to another page, use a render URL with the mvcPath parameter. The <portlet:renderURL> tag constructs the URL and assigns it to a variable.

<portlet:renderURL var="searchURL">
        <portlet:param name="mvcPath" value="/admin/view.jsp" />
</portlet:renderURL>

The render URL is assigned to the searchURL variable specified by the var attribute. The <portlet:param> tag above assigns JSP path /admin/view.jsp to the render parameter mvcPath. The controller’s render method gets the JSP path from the mvcPath parameter to render the following JSP:

docs.liferaymvc.web/src/main/resources/META-INF/resources/admin/view.jsp

To invoke the render URL, assign its variable (the one set to the var attribute of the <portlet:renderURL>) to an action for a UI component, such as a button or navigation bar item.

Action methods are different because they invoke an action (i.e., code), rather than just linking to another page. In your JSP, use a <portlet:actionURL> tag to create an action URL and then assign that URL as an action for a UI component. Here’s an action URL that calls a controller method named doSomething.

<portlet:actionURL name="doSomething" var="doSomethingURL">
    <portlet:param name="redirect" value="<%= redirect %>" />
</portlet:actionURL>

The portlet parameter named redirect is assigned to a JSP path for the portlet to redirect to after invoking the portlet action. This action URL is assigned to a variable named doSomethingURL. As with a render URL, you can assign an action URL to a UI component action by the action URL’s variable (the one set to var).

These simple examples demonstrate how the Liferay MVC framework facilitates communication between a smaller application’s view layer and controller.