Package org.apache.struts.action

Class Action

java.lang.Object
org.apache.struts.action.Action
All Implemented Interfaces:
Serializable
public class Action extends Object implements Serializable

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

  • Field Details

    • ERROR

      public static final String ERROR
      The action execution was a failure. Show an error view, possibly asking the user to retry entering data.
      Since:
      Struts 1.4
      See Also:

    • INPUT

      public static final String INPUT
      The action execution require more input in order to succeed. This result is typically used if a form handling action has been executed so as to provide defaults for a form. The form associated with the handler should be shown to the end user.

      This result is also used if the given input params are invalid, meaning the user should try providing input again.

      Since:
      Struts 1.4
      See Also:

    • LOGIN

      public static final String LOGIN
      The action could not execute, since the user most was not logged in. The login view should be shown.
      Since:
      Struts 1.4
      See Also:

    • SUCCESS

      public static final String SUCCESS
      The action execution was successful. Show result view to the end user.
      Since:
      Struts 1.4
      See Also:

    • servlet

      protected transient ActionServlet servlet

      The servlet to which we are attached.

  • Constructor Details

    • Action

      public Action()

  • Method Details

    • 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