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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 Result Types

The framework

Overview

Results of an Action are used in Webwork to map to a view implementation(ex. jsp, vm, html) or another action. Keep in mind though, the com.opensymphony.xwork.Result interface represents a generic interface for all action execution results, whether that be displaying a webpage, generating an email, sending a JMS message, etc.

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.

<!-- xwork.xml  -->

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

Result Types

Webwork provides several implementations of the com.opensymphony.xworkxwork2.Result interface to make web-based interactions with your actions simple. These result types include:

Results are specified in xwork.xml nested inside actions. The location param is the default parameter, meaning you can specify the location two ways:

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

or

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

...

Includes or forwards a view (usually a jsp)

<result name="success" type="dispatcher">
    <param name="location">foo.jsp</param>
</result>

...

<result name="success" type="redirect">
    <param name="location">foo.jsp</param>
    <param name="parse">false</param>
</result>

...

, ready to use in your own applications.

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">

<result name="success" type="chain">
    <param name="actionName">bar</param>
</result>

invokes this

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

...

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

...

<result name="success" type="freemarker">foo.ftl</result>

...

<result name="success" type="jasper">
    <param name="location">foo.jasper</param>
    <param name="dataSource">mySource</param>
    <param name="format">CSV</param>
</result>

or for pdf

<result name="success" type="jasper">
    <param name="location">foo.jasper</param>
    <param name="dataSource">mySource</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

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