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When an Action action class method completes, it returns a String. The value of the String is used to select a result element. An action mapping will often have a set of results representing different possible outcomes. A standard set of result tokens are defined by the ActionSupport base class.

String SUCCESS = "success";
String NONE    = "none";
String ERROR   = "error";
String INPUT   = "input";
String LOGIN   = "login";

...

Returning ActionSupport.NONE (or null) from an Action action class method causes the results processing to be skipped. This is useful if the action fully handles the result processing such as writing directly to the HttpServletResponse OutputStream.

...

<result-types>
   <result-type name="dispatcher" default="true"
                class="org.apache.struts2.dispatcher.ServletDispatcherResult" />
</result-types>

If a type attribute is not specified, the framework will use the default dispatcher type, which forwards to another web resource. If the resource is a JavaServer Page, then the container will render it, using its JSP engine.

...

Using these intelligent defaults, the most often used result types also become the simplest.

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

<result>
    <param name="location">/ThankYou.jsp</param>
</result>

The param tag sets a property on the Result object. The most commonly-set property is location, which usually specifies the path to a web resources. The param attribute is another intelligent default.

<result>/ThankYou.jsp</result>

Mixing results with intelligent defaults with other results makes it easier to see the "critical path".

<action name="Hello">
    <result>/hello/Result.jsp</result>
    <result name="error">/hello/Error.jsp</result>
    <result name="input">/hello/Input.jsp</result>
</action>

A special 'other' result can be configured by adding a result with name="*". This result will only be selected if no result is found with a matching name.

<action name="Hello">
    <result>/hello/Result.jsp</result>
    <result name="error">/hello/Error.jsp</result>
    <result name="input">/hello/Input.jsp</result>
    <result name="*">/hello/Other.jsp</result>
</action>

...

In most cases if an action returns an unrecognized result name this would be a programming error and should be fixed.

Multiple names

It is possible to define multiple names for the same result:

<action name="save">
    <result>success.jsp</result>
    <result name="error, input">input-form.jsp</result>
</action>

Such functionality was added in Struts 2.5

Global Results

Most often, results are nested with the action element. But some results apply to multiple actions. In a secure application, a client might try to access a page without being authorized, and many actions may need access to a "logon" result.

If actions need to share results, a set of global results can be defined for each package. The framework will first look for a local result nested in the action. If a local match is not found, then the global results are checked.

<global-results>
    <result name="error">/Error.jsp</result>
    <result name="invalid.token">/Error.jsp</result>
    <result name="login" type="redirectAction">Logon!input</result>
</global-results>

...

Result values may be retrieved from its corresponding Action implementation by using EL expressions that access the Action's properties, just like the Struts 2 tag libraries. So given the following Action fragment:

private String nextAction;

public String getNextAction() {
    return nextAction;
}

you might define a result like this:

<action name="fragment" class="FragmentAction">
    <result name="next" type="redirectAction">${nextAction}</result>
</action>

...

See Parameters in configuration results for an expanded discussion.

Returning Result Objects

Instead of configuring results and returning the name, it is possible to return a result object:

public Result runAction() {
	ServletDispatcherResult result = new ServletDispatcherResult();
	result.setLocation("input-form.jsp");
	return result;
}