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.
<!-- parts of xwork.xml -->
....
<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-types>
....
<!-- this action uses the result type dispatcher which is defined above -->
<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.xwork.Result interface to make web-based interactions with your actions simple. These result types include:
Result Type |
name |
class |
|---|---|---|
dispatcher |
com.opensymphony.webwork.dispatcher.ServletDispatcherResult |
|
redirect |
com.opensymphony.webwork.dispatcher.ServletRedirectResult |
|
chain |
com.opensymphony.xwork.ActionChainResult |
|
velocity |
com.opensymphony.webwork.dispatcher.VelocityResult |
|
freemarker |
com.opensymphony.webwork.views.freemarker.FreemarkerResult |
|
jasper |
com.opensymphony.webwork.views.jasperreports.JasperReportsResult |
|
xslt |
com.opensymphony.webwork.views.xslt.XSLTResult |
|
|
com.opensymphony.webwork.dispatcher.HttpHeaderResult |
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 and global-results
Dispatcher
Includes or forwards a view (usually a jsp)
Parameters |
Required |
Description |
|---|---|---|
location |
yes |
the location to go to after execution (ex. jsp) |
parse |
no |
true by default. If set to false, the location param will not be parsed for Ognl expressions |
<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. The consequence of doing this means that the action that was just executed is lost or no longer available. This is because actions are built on a single-thread model.
Parameters |
Required |
Description |
|---|---|---|
location |
yes |
the location to go to after execution |
parse |
no |
true by default. If set to false, the location param will not be parsed for 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.
Parameters |
Required |
Description |
|---|---|---|
actionName |
yes |
the name of the action that will be chained to |
namespace |
no |
sets the namespace of the Action that we're chaining to. If namespace is null, this defaults to the current namespace. |
<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.
Parameters |
Required |
Description |
|---|---|---|
location |
yes |
the location to go to after execution |
parse |
no |
true by default. If set to false, the location param will not be parsed for Ognl expressions |
<result name="success" type="velocity">
<param name="location">foo.vm</param>
</result>
FreeMarker
Parameters |
Required |
Description |
|---|---|---|
location |
yes |
the location to go to after execution |
parse |
no |
true by default. If set to false, the location param will not be parsed for Ognl expressions |
contentType |
no |
defaults to "text/html" unless specified |
<result name="success" type="freemarker">foo.ftl</result>
JasperReports
Generates a JasperReports report using the specified format or PDF if no format is specified.
Parameters |
Required |
Description |
|---|---|---|
location |
yes |
the location to go to after execution |
parse |
no |
true by default. If set to false, the location param will not be parsed for Ognl expressions |
dataSource |
yes |
the Ognl expression used to retrieve the datasource from the value stack (usually a List) |
format |
no |
the format in which the report should be generated, defaults to pdf |
<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.
Parameters |
Required |
Description |
|---|---|---|
location |
yes |
the location to go to after execution |
parse |
no |
Defaults to false. If set to true, the location will be parsed for Ognl expressions |
<result name="success" type="xslt">foo.xslt</result>
HttpHeader
A custom Result type for evaluating HTTP headers against the ValueStack.
Parameters |
Required |
Description |
|---|---|---|
status |
no |
the http servlet response status code that should be set on a response |
parse |
no |
true by default. If set to false, the headers param will not be parsed for Ognl expressions |
headers |
no |
header values |
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>