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Struts 2 Portlet Tutorial - Creating a simple Bookmark Portlet

Work in progress

Using version 2.1.1-SNAPSHOT of the portlet plugin

Note that this tutorial assumes that you're familiar with basic Struts 2 web application programming.

If you have not used Struts 2 before, please check out some of the other Struts 2 tutorials first.

Preparations

In this tutorial we will use eclipse as our IDE. If you do not have Eclipse, you can download it from http://www.eclipse.org.

The project itself will be set up using Maven 2. Maven 2 is available from http://maven.apache.org.

If you have not used the maven-eclipse-plugin before, you need to set up the Eclipse workspace with a variable that points to the Maven 2 repository. To do this, type 

mvn -Declipse.workspace=<path-to-eclipse-workspace> eclipse:add-maven-repo

Creating the project

We'll use Maven 2 with the Struts 2 Portlet Archetype to create a skeleton project for our portlet application. From the command line, issue the command:

mvn archetype:create -DarchetypeGroupId=org.apache.struts -DarchetypeArtifactId=struts2-archetype-portlet -DarchetypeVersion=2.1.1-SNAPSHOT -DartifactId=bookmark-portlet -DgroupId=com.mycompany

This will set up the maven 2 structure for us and also set up the basic configuration needed to create a Struts 2 portlet. The archetype creates a sample HelloWorld portlet that shows off some of the basic principles of Struts 2 portlet programming. To test the set up, type 

mvn jetty:run -P pluto-embedded

in a command prompt. Open a browser and point your browser to http://localhost:8080/bookmark-portlet/pluto/index.jsp and play around.

Looking at the basics

To see how the basic HelloWorld example works, let's look at some of the configuration files, starting with the JSR168 portlet descriptor

src/main/webapp/WEB-INF/portlet.xml
<?xml version="1.0" encoding="UTF-8"?>

<portlet-app
    version="1.0"
    xmlns="http://java.sun.com/xml/ns/portlet/portlet-app_1_0.xsd"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/portlet/portlet-app_1_0.xsd http://java.sun.com/xml/ns/portlet/portlet-app_1_0.xsd"
    id="bookmark-portlet">

	<portlet id="HelloPortlet">
		<description xml:lang="EN">Simple hello world portlet</description>
		<portlet-name>HelloPortlet</portlet-name>
		<display-name xml:lang="EN">bookmark-portlet</display-name>
		
		<portlet-class>org.apache.struts2.portlet.dispatcher.Jsr168Dispatcher</portlet-class>
		
		<!-- The namespace for the actions configured for view mode -->
		<init-param>
			<name>viewNamespace</name>
			<value>/view</value>
		</init-param>
		
		<!-- The default action to invoke in view mode. -->
		<init-param>
			<name>defaultViewAction</name>
			<value>index</value>
		</init-param>
		
		<!-- The namespace for the actions configured for edit mode -->
		<init-param>
			<name>editNamespace</name>
			<value>/edit</value>
		</init-param>
		
		<!-- The default action to invoke in edit mode. -->
		<init-param>
			<name>defaultEditAction</name>
			<value>index!input</value>
		</init-param>
		
		<expiration-cache>0</expiration-cache>
		
		<supports>
			<mime-type>text/html</mime-type>
			<portlet-mode>view</portlet-mode>
			<portlet-mode>edit</portlet-mode>
		</supports>
		
		<supported-locale>en</supported-locale>
		
		<portlet-info>
			<title>HelloPortlet</title>
			<short-title>HelloPortlet</short-title>
			<keywords>struts 2,portlet,hello,world</keywords>
		</portlet-info>
	</portlet>
  
</portlet-app>

The important parts to notice are the portlet-class and init-param elements. The portlet-class elements is always org.apache.struts2.portlet.dispatcher.Jsr168Dispatcher (or a subclass, if you have added some custom functionality). This is the portlet that acts as the dispatcher for the Struts 2 framework, and translates incoming user interaction to action requests that Struts 2 understands. The init-params viewNamespace, defaultViewAction, editNamespace and defaultEditAction set up some defaults for the dispatcher when the portlet encounters a portlet mode without a specific action. Here, we set up the view portlet mode to map to the /view action namespace, and the edit portlet mode to map to the /edit action namespace. We also specify that the default actions for the mentioned portlet modes are index and index!input respectively. We will recognize these namespaces in the next file:

struts.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
    "http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>
    <package name="default" extends="struts-portlet-default" namespace="/view">
        <action name="index" class="com.mycompany.HelloAction">
	    <result>/WEB-INF/jsp/view/index.jsp</result>
	</action>
   </package>
	
   <package name="edit" extends="struts-portlet-default" namespace="/edit">
	<action name="index" class="com.mycompany.UpdateNameAction">
	    <result type="redirectAction">
	        <param name="actionName">index</param>
		<param name="portletMode">view</param>
	    </result>
	    <result name="input">/WEB-INF/jsp/edit/index.jsp</result>
	</action>
    </package>
</struts>

As we can see, the actions for the view portlet mode is in the default package, with /view as namespace, and the actions for the edit portlet mode is in the edit package, with /edit as namespace.

Import the project into Eclipse

Now let's import the project into Eclipse. First, type 

mvn eclipse:eclipse -P pluto-embedded

Then start Eclipse (if you have not already done so), and import the project using "File -> Import -> General -> Existing Projects into Workspace". Browse to the folder where you created the project and press finish. Your portlet project should now be setup up with all dependencies in place.

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