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Apache Struts 2 is an elegant, extensible framework for building enterprise-ready Java web applications. Distributions of Struts 2 are available as a free download under the Apache License.

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• For more about the Apache Struts project itself, visit the project web site.

Getting Started

The documentation is grouped into three areas.

An overview of all three areas is available.

Distributions

For your convenience, a one-stop all distribution is available. Individual elements of the distribution may also be downloaded separately.

Apache Struts 2 in a Nutshell

Apache Struts 2 is a flexible control layer based on standard technologies like Java Filters, JavaBeans, ResourceBundles, Locales, and XML, as well as various OpenSymphony packages, like OGNL and XWork. The framework helps you create an extensible development environment for your application, based on industry standards and proven design patterns.

The framework provides its own web Controller component and integrates with other technologies to provide the Model and the View. For the Model, the framework can interact with standard data access technologies, like JDBC and EJB, as well as most any third-party packages, like Cayenne, Hibernate, or iBATIS. For the View, the framework works well with JavaServer Pages, including JSTL and JSF, as well as FreeMarker or Velocity Templates, PDF, XSLT, and other presentation systems.

The framework's Controller acts as a bridge between the application's Model and the web View. When a request is received, the Controller invokes an Action class. The Action class consults with the Model (or, preferably, a Facade representing your Model) to examine or update the application's state. To transfer data between the Model and the View, properties can be placed on the Action class, or on a plain old JavaBean.

Most often, the Model is represented as a graph of JavaBean objects. Preferably, the Model will do the "heavy lifting", and the Action will act as a "traffic cop" or adapter. The framework provides sophisticated, automatic type conversion to simplify transfering data between rich domain objects and text-only HTTP requests.

To make it easier to access dynamic data obtained by an Action, the framework includes a library of custom tags. The tags interact with the framework's validation and internationalization features, to ensure that input is correct and output is localized. The tag library can be used with JSP, FreeMarker, or Velocity.

Struts configuration in a nutshell

A web application uses a deployment descriptor to initialize resources like filters and listeners. The deployment descriptor is formatted as a XML document and named web.xml. Likewise, the framework uses a configuration file, named struts.xml, to initialize its own resources. These resources include action mappings, to direct input to server-side Action classes, and result types, to select output pages.

Here's a simple configuration (struts.xml) for a login workflow:

<struts>
    <include file="struts-default.xml"/>

    <package name="default" namespace="/" extends="struts-default">

        <action name="Logon" class="mailreader2.Logon">
            <result name="input">/pages/Logon.jsp</result>
            <result name="cancel" type="redirect-action">Welcome</result>
            <result type="redirect-action">MainMenu</result>
            <result name="expired" type="chain">ChangePassword</result>
        </action>

        <action name="Logoff" class="mailreader2.Logoff">
            <result type="redirect-action">Welcome</result>
        </action>

    </package>
</struts>

Aside from actions and results, you can also specify exception handlers and interceptors. Interceptors specify the "request-processing lifecycle" for an action. (What happens to the request before and after the Action class fires.) You can specify both global and local lifecycles. If some of your actions respond to AJAX, SOAP, or JSF requests, you can simplify the lifecycle, and even just "pass through" the request, if you like.

Struts 2 is extensible. Very extensible. Every class deployed by the framework is based on an interface. We provide base classes, but you can substitute your own. In the case of Action classes, even the interface is optional. POJO web development is here!

• Quickstart with Struts 2 Maven Archetypes.
• Struts 2 is extended using Plugins. A list of available plugins is available at the Struts 2 Plugin Registry.
• Tired of XML-based configurations, or need some extra agility? Try the Convention Plugin or its RESTful cousin, the REST Plugin.
• Interested in books, articles, and presentations about Struts? Check out some Other Resources.
• For other community-supported Struts resources, visit the Struts 2 Wiki.

The documentation is grouped into four areas.

Community Wiki

The Struts 2 Community Wiki is an additional resource. It is not distributed with Struts 2, and contributions to the community wiki do not require a CLAThe framework provides general-purpose defaults, so you can start using Struts 2 "out of the box" right away. As needed, you can override any of our defaults in your application's configuration. We provide the base framework, but you can still write your application your way.

Quick Links

• Apache Struts Home

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• Distributions
• Project FAQ
• Mailing lists
• Issue Tracking (JIRA)

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• Planet Struts
• Struts Central
• Apache Bookstore
• WebWork wiki in Chinese

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• Struts 2 Wiki space