Action (Struts Core 1.3.10 API)

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## org.apache.struts.action
Class Action

    java.lang.Object
      org.apache.struts.action.Action

Direct Known Subclasses:
  MockAction

    public class Action

extends Object

An Action is an adapter between the contents of an incoming HTTP request and the corresponding business logic that should be executed to process this request. The controller (RequestProcessor) will select an appropriate Action for each request, create an instance (if necessary), and call the `execute` method.

Actions must be programmed in a thread-safe manner, because the controller will share the same instance for multiple simultaneous requests. This means you should design with the following items in mind:

- Instance and static variables MUST NOT be used to store information related to the state of a particular request. They MAY be used to share global resources across requests for the same action.
- Access to other resources (JavaBeans, session variables, etc.) MUST be synchronized if those resources require protection. (Generally, however, resource classes should be designed to provide their own protection where necessary.

When an `Action` instance is first created, the controller will call `setServlet` with a non-null argument to identify the servlet instance to which this Action is attached. When the servlet is to be shut down (or restarted), the `setServlet` method will be called with a `null` argument, which can be used to clean up any allocated resources in use by this Action.

Version:
  $Rev: 471754 $ $Date: 2005-08-26 21:58:39 -0400 (Fri, 26 Aug 2005) $

Field Summary
`protected ActionServlet` | `servlet` The servlet to which we are attached.

Constructor Summary
`Action()`

Method Summary
`protected void` | `addErrors(HttpServletRequest request, ActionMessages errors)` Adds the specified errors keys into the appropriate request attribute for use by the <html:errors> tag, if any messages are required.
`protected void` | `addMessages(HttpServletRequest request, ActionMessages messages)` Adds the specified messages keys into the appropriate request attribute for use by the <html:messages> tag (if messages="true" is set), if any messages are required.
`ActionForward` | `execute(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response)` Process the specified HTTP request, and create the corresponding HTTP response (or forward to another web component that will create it), with provision for handling exceptions thrown by the business logic.
`ActionForward` | `execute(ActionMapping mapping, ActionForm form, ServletRequest request, ServletResponse response)` Process the specified non-HTTP request, and create the corresponding non-HTTP response (or forward to another web component that will create it), with provision for handling exceptions thrown by the business logic.
`protected String` | `generateToken(HttpServletRequest request)` Generate a new transaction token, to be used for enforcing a single request for a particular transaction.
`protected ActionMessages` | `getErrors(HttpServletRequest request)` Retrieves any existing errors placed in the request by previous actions.
`protected Locale` | `getLocale(HttpServletRequest request)` Return the user's currently selected Locale.
`protected ActionMessages` | `getMessages(HttpServletRequest request)` Retrieves any existing messages placed in the request by previous actions.
`protected MessageResources` | `getResources(HttpServletRequest request)` Return the default message resources for the current module.
`protected MessageResources` | `getResources(HttpServletRequest request, String key)` Return the specified message resources for the current module.
`ActionServlet` | `getServlet()` Return the servlet instance to which we are attached.
`protected boolean` | `isCancelled(HttpServletRequest request)` Returns `true` if the current form's cancel button was pressed.
`protected boolean` | `isTokenValid(HttpServletRequest request)` Return `true` if there is a transaction token stored in the user's current session, and the value submitted as a request parameter with this action matches it.
`protected boolean` | `isTokenValid(HttpServletRequest request, boolean reset)` Return `true` if there is a transaction token stored in the user's current session, and the value submitted as a request parameter with this action matches it.
`protected void` | `resetToken(HttpServletRequest request)` Reset the saved transaction token in the user's session.
`protected void` | `saveErrors(HttpServletRequest request, ActionMessages errors)` Save the specified error messages keys into the appropriate request attribute for use by the <html:errors> tag, if any messages are required.
`protected void` | `saveErrors(HttpSession session, ActionMessages errors)` Save the specified error messages keys into the appropriate session attribute for use by the <html:messages> tag (if messages="false") or <html:errors>, if any error messages are required.
`protected void` | `saveMessages(HttpServletRequest request, ActionMessages messages)` Save the specified messages keys into the appropriate request attribute for use by the <html:messages> tag (if messages="true" is set), if any messages are required.
`protected void` | `saveMessages(HttpSession session, ActionMessages messages)` Save the specified messages keys into the appropriate session attribute for use by the <html:messages> tag (if messages="true" is set), if any messages are required.
`protected void` | `saveToken(HttpServletRequest request)` Save a new transaction token in the user's current session, creating a new session if necessary.
`protected void` | `setLocale(HttpServletRequest request, Locale locale)` Set the user's currently selected `Locale` into their `HttpSession`.
`void` | `setServlet(ActionServlet servlet)` Set the servlet instance to which we are attached (if `servlet` is non-null), or release any allocated resources (if `servlet` is null).

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

Field Detail

### servlet

    protected transient ActionServlet servlet

  The servlet to which we are attached.

Constructor Detail

### Action

    public Action()

Method Detail

### getServlet

    public ActionServlet getServlet()

  Return the servlet instance to which we are attached.

  Returns:
    The servlet instance to which we are attached.

### setServlet

    public void setServlet(ActionServlet servlet)

  Set the servlet instance to which we are attached (if `servlet` is non-null), or release any allocated resources (if `servlet` is null).

  Parameters:
    `servlet` - The new controller servlet, if any

### execute

    public ActionForward execute(ActionMapping mapping,
                                 ActionForm form,
                                 ServletRequest request,
                                 ServletResponse response)
                          throws Exception

  Process the specified non-HTTP request, and create the corresponding non-HTTP response (or forward to another web component that will create it), with provision for handling exceptions thrown by the business logic. Return an `ActionForward` instance describing where and how control should be forwarded, or `null` if the response has already been completed.

  The default implementation attempts to forward to the HTTP version of this method.

  Parameters:
    `mapping` - The ActionMapping used to select this instance
    `form` - The optional ActionForm bean for this request (if any)
    `request` - The non-HTTP request we are processing
    `response` - The non-HTTP response we are creating
  Returns:
    The forward to which control should be transferred, or `null` if the response has been completed.
  Throws:
    `Exception` - if the application business logic throws an exception.
  Since:
    Struts 1.1

### execute

    public ActionForward execute(ActionMapping mapping,
                                 ActionForm form,
                                 HttpServletRequest request,
                                 HttpServletResponse response)
                          throws Exception

  Process the specified HTTP request, and create the corresponding HTTP response (or forward to another web component that will create it), with provision for handling exceptions thrown by the business logic. Return an `ActionForward` instance describing where and how control should be forwarded, or `null` if the response has already been completed.

  Parameters:
    `mapping` - The ActionMapping used to select this instance
    `form` - The optional ActionForm bean for this request (if any)
    `request` - The HTTP request we are processing
    `response` - The HTTP response we are creating
  Returns:
    The forward to which control should be transferred, or `null` if the response has been completed.
  Throws:
    `Exception` - if the application business logic throws an exception
  Since:
    Struts 1.1

### addMessages

    protected void addMessages(HttpServletRequest request,
                               ActionMessages messages)

  Adds the specified messages keys into the appropriate request attribute for use by the <html:messages> tag (if messages="true" is set), if any messages are required. Initialize the attribute if it has not already been. Otherwise, ensure that the request attribute is not set.

  Parameters:
    `request` - The servlet request we are processing
    `messages` - Messages object
  Since:
    Struts 1.2.1

### addErrors

    protected void addErrors(HttpServletRequest request,
                             ActionMessages errors)

  Adds the specified errors keys into the appropriate request attribute for use by the <html:errors> tag, if any messages are required. Initialize the attribute if it has not already been. Otherwise, ensure that the request attribute is not set.

  Parameters:
    `request` - The servlet request we are processing
    `errors` - Errors object
  Since:
    Struts 1.2.1

### generateToken

    protected String generateToken(HttpServletRequest request)

  Generate a new transaction token, to be used for enforcing a single request for a particular transaction.

  Parameters:
    `request` - The request we are processing
  Returns:
    The new transaction token.

### getErrors

    protected ActionMessages getErrors(HttpServletRequest request)

  Retrieves any existing errors placed in the request by previous actions. This method could be called instead of creating a `new ActionMessages()` at the beginning of an `Action`. This will prevent saveErrors() from wiping out any existing Errors

  Parameters:
    `request` - The servlet request we are processing
  Returns:
    the Errors that already exist in the request, or a new ActionMessages object if empty.
  Since:
    Struts 1.2.1

### getLocale

    protected Locale getLocale(HttpServletRequest request)

  Return the user's currently selected Locale.

  Parameters:
    `request` - The request we are processing
  Returns:
    The user's currently selected Locale.

### getMessages

    protected ActionMessages getMessages(HttpServletRequest request)

  Retrieves any existing messages placed in the request by previous actions. This method could be called instead of creating a `new ActionMessages()` at the beginning of an `Action` This will prevent saveMessages() from wiping out any existing Messages

  Parameters:
    `request` - The servlet request we are processing
  Returns:
    the Messages that already exist in the request, or a new ActionMessages object if empty.
  Since:
    Struts 1.2.1

### getResources

    protected MessageResources getResources(HttpServletRequest request)

  Return the default message resources for the current module.

  Parameters:
    `request` - The servlet request we are processing
  Returns:
    The default message resources for the current module.
  Since:
    Struts 1.1

### getResources

    protected MessageResources getResources(HttpServletRequest request,
                                            String key)

  Return the specified message resources for the current module.

  Parameters:
    `request` - The servlet request we are processing
    `key` - The key specified in the message-resources element for the requested bundle.
  Returns:
    The specified message resource for the current module.
  Since:
    Struts 1.1

### isCancelled

    protected boolean isCancelled(HttpServletRequest request)

  Returns `true` if the current form's cancel button was pressed. This method will check if the `Globals.CANCEL_KEY` request attribute has been set, which normally occurs if the cancel button generated by CancelTag was pressed by the user in the current request. If `true`, validation performed by an ActionForm's `validate()` method will have been skipped by the controller servlet.

  Since Action 1.3.0, the mapping for a cancellable Action must also have the new "cancellable" property set to true. If "cancellable" is not set, and the magic Cancel token is found in the request, the standard Composable Request Processor will throw an InvalidCancelException.

  Parameters:
    `request` - The servlet request we are processing
  Returns:
    `true` if the cancel button was pressed; `false` otherwise.

### isTokenValid

    protected boolean isTokenValid(HttpServletRequest request)

  Return `true` if there is a transaction token stored in the user's current session, and the value submitted as a request parameter with this action matches it. Returns `false` under any of the following circumstances:

  - No session associated with this request
  - No transaction token saved in the session
  - No transaction token included as a request parameter
  - The included transaction token value does not match the transaction token in the user's session

  Parameters:
    `request` - The servlet request we are processing
  Returns:
    `true` if there is a transaction token and it is valid; `false` otherwise.

### isTokenValid

    protected boolean isTokenValid(HttpServletRequest request,
                                   boolean reset)

  Return `true` if there is a transaction token stored in the user's current session, and the value submitted as a request parameter with this action matches it. Returns `false` under any of the following circumstances:

  - No session associated with this request
  - No transaction token saved in the session
  - No transaction token included as a request parameter
  - The included transaction token value does not match the transaction token in the user's session

  Parameters:
    `request` - The servlet request we are processing
    `reset` - Should we reset the token after checking it?
  Returns:
    `true` if there is a transaction token and it is valid; `false` otherwise.

### resetToken

    protected void resetToken(HttpServletRequest request)

  Reset the saved transaction token in the user's session. This indicates that transactional token checking will not be needed on the next request that is submitted.

  Parameters:
    `request` - The servlet request we are processing

### saveErrors

    protected void saveErrors(HttpServletRequest request,
                              ActionMessages errors)

  Save the specified error messages keys into the appropriate request attribute for use by the <html:errors> tag, if any messages are required. Otherwise, ensure that the request attribute is not created.

  Parameters:
    `request` - The servlet request we are processing
    `errors` - Error messages object
  Since:
    Struts 1.2

### saveMessages

    protected void saveMessages(HttpServletRequest request,
                                ActionMessages messages)

  Save the specified messages keys into the appropriate request attribute for use by the <html:messages> tag (if messages="true" is set), if any messages are required. Otherwise, ensure that the request attribute is not created.

  Parameters:
    `request` - The servlet request we are processing.
    `messages` - The messages to save. `null` or empty messages removes any existing ActionMessages in the request.
  Since:
    Struts 1.1

### saveMessages

    protected void saveMessages(HttpSession session,
                                ActionMessages messages)

  Save the specified messages keys into the appropriate session attribute for use by the <html:messages> tag (if messages="true" is set), if any messages are required. Otherwise, ensure that the session attribute is not created.

  Parameters:
    `session` - The session to save the messages in.
    `messages` - The messages to save. `null` or empty messages removes any existing ActionMessages in the session.
  Since:
    Struts 1.2

### saveErrors

    protected void saveErrors(HttpSession session,
                              ActionMessages errors)

  Save the specified error messages keys into the appropriate session attribute for use by the <html:messages> tag (if messages="false") or <html:errors>, if any error messages are required. Otherwise, ensure that the session attribute is empty.

  Parameters:
    `session` - The session to save the error messages in.
    `errors` - The error messages to save. `null` or empty messages removes any existing error ActionMessages in the session.
  Since:
    Struts 1.3

### saveToken

    protected void saveToken(HttpServletRequest request)

  Save a new transaction token in the user's current session, creating a new session if necessary.

  Parameters:
    `request` - The servlet request we are processing

### setLocale

    protected void setLocale(HttpServletRequest request,
                             Locale locale)

  Set the user's currently selected `Locale` into their `HttpSession`.

  Parameters:
    `request` - The request we are processing
    `locale` - The user's selected Locale to be set, or null to select the server's default Locale

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