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## com.ibm.portal.struts.action
Class DispatchAction

    java.lang.Object
      Action
          com.ibm.portal.struts.action.StrutsAction
              com.ibm.portal.struts.action.DispatchAction

Direct Known Subclasses:
  LookupDispatchAction

    public abstract class DispatchAction

extends StrutsAction

This is a Portal friendly version of DispatchAction. The basic difference is the request object is a PortletRequest object and there is no response object.

Derived from the Struts DispatchAction javadoc:

An abstract Action that dispatches to a public method that is named by the request parameter whose name is specified by the `parameter` property of the corresponding ActionMapping. This Action is useful for developers who prefer to combine many similar actions into a single Action class, in order to simplify their application design.

To configure the use of this action in your `struts-config.xml` file, create an entry like this:

`<action path="/saveSubscription" type="org.apache.struts.actions.DispatchAction" name="subscriptionForm" scope="request" input="/subscription.jsp" parameter="method"/>`

which will use the value of the request parameter named "method" to pick the appropriate "execute" method, which must have the same signature (other than method name) of the standard Action.execute method. For example, you might have the following three methods in the same action:

- public ActionForward delete(ActionMapping mapping, ActionForm form, PortletRequest request ) throws Exception
- public ActionForward insert(ActionMapping mapping, ActionForm form, PortletRequest request) throws Exception
- public ActionForward update(ActionMapping mapping, ActionForm form, PortletRequest request) throws Exception

and call one of the methods with a URL like this:

`<html:link action="/saveSubscription.do?method=update">`

NOTE - All of the other mapping characteristics of this action must be shared by the various handlers. This places some constraints over what types of handlers may reasonably be packaged into the same `DispatchAction` subclass.

Since:
  5.1

Field Summary
`protected java.lang.Class` | `clazz` The Class instance of this `DispatchAction` class.
`protected static Log` | `log` Commons Logging instance.
`protected static MessageResources` | `messages` The message resources for this package.
`protected java.util.HashMap` | `methods` The set of Method objects introspected for this class, keyed by method name.
`protected java.lang.Class[]` | `types` The set of argument type classes for the reflected method call.

Constructor Summary
`DispatchAction()` DispatchAction constructor.

Method Summary
`protected ActionForward` | `dispatchMethod(ActionMapping mapping, ActionForm form, ActionRequest request, ActionResponse response, java.lang.String name)` Dispatches to the specified method.
`ActionForward` | `execute(ActionMapping mapping, ActionForm form, ActionRequest request, ActionResponse response)` Processes the current request based on the ActionMapping information.
`protected java.lang.reflect.Method` | `getMethod(java.lang.String name)` Introspect the current class to identify a method of the specified name that accepts the same parameter types as the `execute` method does.
`protected ActionForward` | `unspecified(ActionMapping mapping, ActionForm form, ActionRequest request)` Method which is dispatched to when there is no value for specified request parameter included in the request.

Methods inherited from class com.ibm.portal.struts.action.StrutsAction
`sendError, sendError, sendError, sendError, sendError, sendError`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### clazz

    protected java.lang.Class clazz

  The Class instance of this `DispatchAction` class.

### log

    protected static Log log

  Commons Logging instance.

### messages

    protected static MessageResources messages

  The message resources for this package.

### methods

    protected java.util.HashMap methods

  The set of Method objects introspected for this class, keyed by method name. This collection is populated as different methods are called, so that introspection needs to occur only once per method name.

  Derived from the Struts DispatchAction javadoc.

### types

    protected java.lang.Class[] types

  The set of argument type classes for the reflected method call. These are the same for all calls, so calculate them only once.

  Derived from the Struts DispatchAction javadoc.

Constructor Detail

### DispatchAction

    public DispatchAction()

  DispatchAction constructor.

Method Detail

### execute

    public ActionForward execute(ActionMapping mapping,
                                 ActionForm form,
                                 ActionRequest request,
                                 ActionResponse response)
                          throws java.lang.Exception

  Processes the current request based on the ActionMapping information. The processing should return an ActionForward, to control the processing. This implementation does not allow the response object to be written to directly, so an ActionForward should be returned. A `null` return value will stop the request processing, but will not result in the creation of a new `IViewCommand`

  Overrides:
    `execute` in class `StrutsAction`
  Parameters:
    `mapping` - The ActionMapping used to select this instance
    `form` - The optional ActionForm bean for this request (if any)
    `request` - The portlet request being processed
    `response` - The portlet response being processed
  Returns:
    the action forward for the mapping parameter
  Throws:
    `java.lang.Exception` - if an exception occurs

### unspecified

    protected ActionForward unspecified(ActionMapping mapping,
                                        ActionForm form,
                                        ActionRequest request)
                                 throws java.lang.Exception

  Method which is dispatched to when there is no value for specified request parameter included in the request. Subclasses of `DispatchAction` should override this method if they wish to provide default behavior different than producing an HTTP "Bad Request" error.

  Derived from the Struts DispatchAction javadoc

  Parameters:
    `mapping` - The ActionMapping used to select this instance
    `form` - The optional ActionForm bean for this request (if any)
    `request` - The portlet request being processed
  Returns:
    the action forward for the unspecified case, can be `null`
  Throws:
    `java.lang.Exception` - if an exception occurs

### dispatchMethod

    protected ActionForward dispatchMethod(ActionMapping mapping,
                                           ActionForm form,
                                           ActionRequest request,
                                           ActionResponse response,
                                           java.lang.String name)
                                    throws java.lang.Exception

  Dispatches to the specified method.

  Parameters:
    `mapping` - The ActionMapping used to select this instance
    `form` - The optional ActionForm bean for this request (if any)
    `request` - The portlet request being processed
    `name` - the dispatch name
  Returns:
    ActionForward the action forward for the specified name
  Throws:
    `java.lang.Exception` - if an exception occurs

### getMethod

    protected java.lang.reflect.Method getMethod(java.lang.String name)
                                          throws java.lang.NoSuchMethodException

  Introspect the current class to identify a method of the specified name that accepts the same parameter types as the `execute` method does.

  Derived from the Struts DispatchAction javadoc.

  Parameters:
    `name` - Name of the method to be introspected
  Returns:
    Method the method object for the specified name
  Throws:
    `java.lang.NoSuchMethodException` - if no such method can be found

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