Struts2 Plugin Development

- Extending Struts2

Justin Yip

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Roadmap Plugin Architecture Extension points Static resources Tag development

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Plugin ArchitectureStruts 2 provides a simple plugin architecture so that developers can

extend the framework just by adding a JAR to the application's classpath.

Struts2 Plugins are contained in a JAR Contains classes and configurations Extend, replace, or add to exsiting Struts framework functionality The JAR should contain a struts-plugin.xml file

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Sample struts-plugin.xml

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Roadmap Plugin Architecture Extension points Static resources Tag development

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Struts2 Plugin provides Packages Interceptors Results Actions Core component Extensions Constants

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Core component Extension Pointstype key

com.opensymphony.xwork2.ObjectFactory struts.objectFactorycom.opensymphony.xwork2.ActionProxyFactory struts.actionProxyFactorycom.opensymphony.xwork2.util.ObjectTypeDeterminer

struts.objectTypeDeterminer

org.apache.struts2.dispatcher.mapper.ActionMapper

struts.mapper.class

org.apache.struts2.dispatcher.multipart.MultiPartRequest

struts.multipart.parser

……

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Plugin examples

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Json-plugin Struts2 json 插件提供了序列化成为 json 对象的功能 插件定义了一个包 “ json-default” ，包内定义了一个结果类型“ json” ，还有一个负责将 java 对象序列化成 json 对象的拦截器

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Spring-plugin Extending core component ：

com.opensymphony.xwork2.ObjectFactory

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Config Browser PluginSee an application's configuration at runtime. It is a small struts2

application. Provide actions, freemarker pages and stylesheets.

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Static resourcesSome plugin, UI widgets in particular, need to provide static

resource(stylesheets, images, etc…) within plugin archive.With struts2 plugin mechanism, you can package these resources in jar.

Static resources are placed under “/static” in plugin jar, and we can refer it in page using “/static” as the path.

Assuming “/static/background.jpg” is inside a plugin jar,And we refer it:<@s.url value="/static/background.jpg" var=“img_bg" />

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Creating a new Project1. Create a new Maven2 project “widgets-accordion” using Archetype:

“maven-archetype-quickstart”2. Fill out Group Id, Artifact Id, version etc.

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Creating a new Project3. Change compiler level to 1.5

• Config “maven-compiler-plugin” below:

• Update project facts using “mvn eclipse:eclipse”

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Creating a new Project4. Add maven dependency

org.apache.struts struts2-core org.apache.struts struts2-json-plugin javax.servlet servlet-api javax.servlet.jsp jsp-api junit junit

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Plugin Entry point5. Create a struts2 plugin configuration6. declare a bean of type “org.apache.struts2.views.TagLibrary”, named

“com.redhat.widget.DemoTagLibrary”

Perfix with “rw”

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Class Diagram

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The class

A custom tag library must be descendant of “org.apache.struts2.views.TagLibraryHere we support freemarker onlyReturn an new instance of DemoModel in getFreemarkerModels

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The freemarker model

accordion.ftl

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The AccordionModel

Returns the tag bean in getBean() method

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Accordion

Theme selecting

Template selecting

Tld class for jsp

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Handling params

Extra params from value stack

Retrieve param value from tagxxx.ftl

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View templateaccordion.ftl

accordion-close.ftl

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Test Drive Install the artifact using “mvn install” Test this tag in demo project

Test our API : $("#a1").trigger("accordion-foldAll")