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Most use cases can be divided into two phases. First, we need to change or query the application's state, and then we need to present an updated view of the application. The Action class manages the application's state, and the Result Type manages the view.

Predefined

See Result Configuration for basic information about how results are configuration.

Overview

Result Types are classes that determine what happens after an Action executes and a Result is returned. Developers are free to create their own Result Types according to the needs of their application or environment. In the framework, for example, Servlet and Velocity Result Types have been created to handle rendering views in web applications.

Note: All built in result types implement the com.opensymphony.xwork.Result interface, which represents a generic interface for all Action execution results, whether that be displaying a webpage, generating an email, sending a JMS message, and so forth.

Result Types define classes and map them to names to be referred in the Action configuration results. This serves as a shorthand name-value pair for these classes.

...

...
<result-types>
    <result-type name="dispatcher" class="com.opensymphony.webwork.dispatcher.ServletDispatcherResult" default="true"/>
    <result-type name="redirect" class="com.opensymphony.webwork.dispatcher.ServletRedirectResult"/>
    <result-type name="velocity" class="com.opensymphony.webwork.dispatcher.VelocityResult"/>
    <result-type name="chain" class="com.opensymphony.xwork.ActionChainResult"/>
    <result-type name="xslt" class="com.opensymphony.webwork.views.xslt.XSLTResult"/>
    <result-type name="jasper" class="com.opensymphony.webwork.views.jasperreports.JasperReportsResult"/>
    <result-type name="freemarker" class="com.opensymphony.webwork.views.freemarker.FreemarkerResult"/>
    <result-type name="httpheader" class="com.opensymphony.webwork.dispatcher.HttpHeaderResult"/>
    <result-type name="stream" class="com.opensymphony.webwork.dispatcher.StreamResult"/>
    <result-type name="plaintext" class="com.opensymphony.webwork.dispatcher.PlainTextResult" />
</result-types>
...

...

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

<package name="myPackage" extends="default">
  <action name="bar" class="myPackage.barAction">
    <!-- default result type is "dispatcher" -->
    <!-- default result name is "success" -->
    <result>foo.jsp</result>
    <result name="error">error.jsp</result>
    </result>
  </action>
</package>

Result Types

The framework provides several implementations of the com.opensymphony.xworkxwork2.Result interface to make web-based interactions with your actions simple. These result types include:, ready to use in your own applications.

Results are specified in a xwork xml config file(xwork.xml) nested inside <action>. If the location param is the only param being specified in the result tag, you can simplify it as follows:

...

<action name="bar" class="myPackage.barAction">
  <result name="success" type="dispatcher">
    <param name="location">foo.jsp</param>
  </result>
</action>

or simplified

...

<action name="bar" class="myPackage.barAction">
  <result name="success" type="dispatcher">foo.jsp</result>
</action>

if you are extending webwork-default.xml, then the default result type is "dispatcher". Also, if you don't specify the name of a result, it is assumed to be "success". This means you can simply the result down to

...

<action name="bar" class="myPackage.barAction">
  <result>foo.jsp</result>
</action>

Note: The Parse attribute enables the location element to be parsed for expressions. An example of how this could be useful:

...

<result name="success" type="redirect">/displayCart.action?userId=${userId}</result>

...

Optional

Additional Result Types can be created and plugged into an application by implementing the com.opensymphony.xwork2.Result interface. Custom Result Types might include generating an email or JMS message, generating images, and so forth.

Default Parameters

To minimize configuration, Results can be configured with a single value, which will be converted into a parameter, and each Result can specify which parameter this value should be set as. For example, here is a result defined in XML that uses a default parameter:

<result type="freemarker">foo.fm</result>

That is the equivalent to this:

<result type="freemarker">
  <param name="location">foo.vm</param>
</result>

Since probably 95% of your actions won't need results that contain multiple parameters, this little shortcut saves you a significant amount of configuration. It also follows that if you have specified the default parameter, you don't need to set the same parameter as a specifically-named parameter.

Registering Result Types

All Result Types are plugged in via the Result Configuration.

Extending

You can always extend defined result types and implement whatever logic you need. To simplify process of that, you can define your custom ResultFactory and use it with connection with custom interface which your Result implements. Check Define dedicated factory to see how to do it.

Struts 2 provides one such extension for you: ParamNameAwareResult interface when used with StrutsResultBuilder can limit parameters assigned to the result. So you can simple extend existing result with such a functionality as below:

public class MyResult extends ServletDispatcherResult implements ParamNameAwareResult {

    public boolean acceptableParamName(String name, String value) {
        return "accept".equals(name);
    }

}

and then register it and use instead of default dispatcher result.

Next: DispatcherListener