Result Types

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 WebWork 2 for example, Servlet and Velocity Result Types have been created to handle rendering views in web applications.

Note: All built in webwork 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, 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.

...
<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-types>
...

{code|title=snippet of your xwork.xml}
<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

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

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>

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>

NOTE: You can also specify global-results to use with multiple actions. This can save time from having to add the same result to many different actions. For more information on result tags and global-results, see [Results] section.

">Dispatcher

Includes or forwards to a view (usually a jsp). Behind the scenes WebWork will use a RequestDispatcher, where the target servlet/JSP receives the same request/response objects as the original servlet/JSP. Therefore, you can pass data between them using request.setAttribute() – the WebWork action is available.

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

">Redirect

The response is told to redirect the browser to the specified location (a new request from the client). The consequence of doing this means that the action (action instance, action errors, field errors, etc) that was just executed is lost and no longer available. This is because actions are built on a single-thread model. The only way to pass data is through the session or with web parameters (url?name=value) which can be OGNL expressions.

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

">Action Chaining

A special kind of view that invokes GenericDispatch (using the previously existing ActionContext) and executes another action. This is useful if you need to execute one action immediately after another.

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

invokes this

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

">Velocity

This result mocks a JSP execution environment and then displays a Velocity template that will be streamed directly to the servlet output.

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

">FreeMarker

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

">JasperReports

Generates a JasperReports report using the specified format or PDF if no format is specified.

<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>

">XML/XSL

Interfaces with xml transformations.

<result name="success" type="xslt">foo.xslt</result>

">HttpHeader

A custom Result type for evaluating HTTP headers against the ValueStack.

Example:

<result name="success" type="header">
    <param name="status">204</param>
    <param name="headers.a">a custom header value</param>
    <param name="headers.b">another custom header value</param>
</result>