org.apache.struts.action
Class Action

java.lang.Object
  |
  +--org.apache.struts.action.Action

Direct Known Subclasses:

ActionBase, AddFormBeanAction, AddForwardAction, AddMappingAction, DispatchAction, ForwardAction, IncludeAction, ReloadAction, RemoveFormBeanAction, RemoveForwardAction, RemoveMappingAction

public class Action

extends java.lang.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 (ActionServlet) will select an appropriate Action for each request, create an instance (if necessary), and call the perform method.

Actions must be programmed in a thread-safe manner, because the controller will share the same instance for multiple simultaneous requests. In 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 servlet will call setServlet() with a non-null argument to identify the controller servlet instance to which this Action is attached. When the controller 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:

$Revision: 1.1 $ $Date$

Author:

Craig R. McClanahan

Field Summary

static java.lang.String	DATA_SOURCE_KEY The context attributes key under which our default configured data source (which must implement javax.sql.DataSource) is stored, if one is configured for this application.
protected static java.util.Locale	defaultLocale The system default Locale.
static java.lang.String	ERROR_KEY The request attributes key under which your action should store an org.apache.struts.action.ActionErrors object, if you are using the corresponding custom tag library elements.
static java.lang.String	EXCEPTION_KEY The request attributes key under which Struts custom tags might store a Throwable that caused them to report a JspException at runtime.
static java.lang.String	FORM_BEANS_KEY The context attributes key under which our org.apache.struts.action.ActionFormBeans collection is normally stored, unless overridden when initializing our ActionServlet.
static java.lang.String	FORWARDS_KEY The context attributes key under which our org.apache.struts.action.ActionForwards collection is normally stored, unless overridden when initializing our ActionServlet.
static java.lang.String	LOCALE_KEY The session attributes key under which the user's selected java.util.Locale is stored, if any.
static java.lang.String	MAPPING_KEY The request attributes key under which our org.apache.struts.ActionMapping instance is passed.
static java.lang.String	MAPPINGS_KEY The context attributes key under which our org.apache.struts.action.ActionMappings collection is normally stored, unless overridden when initializing our ActionServlet.
static java.lang.String	MESSAGES_KEY The context attributes key under which our application resources are normally stored, unless overridden when initializing our ActionServlet.
static java.lang.String	MULTIPART_KEY The request attributes key under which our multipart class is stored.
protected ActionServlet	servlet The controller servlet to which we are attached.
static java.lang.String	SERVLET_KEY The context attributes key under which we store the mapping defined for our controller serlet, which will be either a path-mapped pattern (/action/*) or an extension mapped pattern (*.do).
static java.lang.String	TRANSACTION_TOKEN_KEY The session attributes key under which our transaction token is stored, if it is used.

Constructor Summary

Action()

Method Summary

protected java.lang.String	generateToken(javax.servlet.http.HttpServletRequest request) Generate a new transaction token, to be used for enforcing a single request for a particular transaction.
protected java.util.Locale	getLocale(javax.servlet.http.HttpServletRequest request) Return the user's currently selected Locale.
protected MessageResources	getResources() Return the message resources for this application.
ActionServlet	getServlet() Return the controller servlet instance to which we are attached.
protected boolean	isCancelled(javax.servlet.http.HttpServletRequest request) Returns true if the current form's cancel button was pressed.
protected boolean	isTokenValid(javax.servlet.http.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.
ActionForward	perform(ActionMapping mapping, ActionForm form, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Process the specified HTTP request, and create the corresponding HTTP response (or forward to another web component that will create it).
ActionForward	perform(ActionMapping mapping, ActionForm form, javax.servlet.ServletRequest request, javax.servlet.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).
ActionForward	perform(ActionServlet servlet, ActionMapping mapping, ActionForm form, javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Deprecated. Use the new perform() method without a servlet argument
ActionForward	perform(ActionServlet servlet, ActionMapping mapping, ActionForm form, javax.servlet.ServletRequest request, javax.servlet.ServletResponse response) Deprecated. Use the new perform() method without a servlet argument
protected void	resetToken(javax.servlet.http.HttpServletRequest request) Reset the saved transaction token in the user's session.
protected void	saveErrors(javax.servlet.http.HttpServletRequest request, ActionErrors errors) Save the specified error messages keys into the appropriate request attribute for use by the <struts:errors> tag, if any messages are required.
protected void	saveToken(javax.servlet.http.HttpServletRequest request) Save a new transaction token in the user's current session, creating a new session if necessary.
protected void	setLocale(javax.servlet.http.HttpServletRequest request, java.util.Locale locale) Set the user's currently selected Locale.
void	setServlet(ActionServlet servlet) Set the controller servlet instance to which we are attached (if servlet is non-null), or release any allocated resources (if servlet is null).
protected java.lang.String	toHex(byte[] buffer) Convert a byte array to a String of hexadecimal digits and return it.

Methods inherited from class java.lang.Object

, clone, equals, finalize, getClass, hashCode, notify, notifyAll, registerNatives, toString, wait, wait, wait

Field Detail

DATA_SOURCE_KEY

public static final java.lang.String DATA_SOURCE_KEY

The context attributes key under which our default configured data source (which must implement javax.sql.DataSource) is stored, if one is configured for this application.

ERROR_KEY

public static final java.lang.String ERROR_KEY

The request attributes key under which your action should store an org.apache.struts.action.ActionErrors object, if you are using the corresponding custom tag library elements.

EXCEPTION_KEY

public static final java.lang.String EXCEPTION_KEY

The request attributes key under which Struts custom tags might store a Throwable that caused them to report a JspException at runtime. This value can be used on an error page to provide more detailed information about what really went wrong.

FORM_BEANS_KEY

public static final java.lang.String FORM_BEANS_KEY

The context attributes key under which our org.apache.struts.action.ActionFormBeans collection is normally stored, unless overridden when initializing our ActionServlet.

FORWARDS_KEY

public static final java.lang.String FORWARDS_KEY

The context attributes key under which our org.apache.struts.action.ActionForwards collection is normally stored, unless overridden when initializing our ActionServlet.

LOCALE_KEY

public static final java.lang.String LOCALE_KEY

The session attributes key under which the user's selected java.util.Locale is stored, if any. If no such attribute is found, the system default locale will be used when retrieving internationalized messages. If used, this attribute is typically set during user login processing.

MAPPING_KEY

public static final java.lang.String MAPPING_KEY

The request attributes key under which our org.apache.struts.ActionMapping instance is passed.

MAPPINGS_KEY

public static final java.lang.String MAPPINGS_KEY

The context attributes key under which our org.apache.struts.action.ActionMappings collection is normally stored, unless overridden when initializing our ActionServlet.

MESSAGES_KEY

public static final java.lang.String MESSAGES_KEY

The context attributes key under which our application resources are normally stored, unless overridden when initializing our ActionServlet.

MULTIPART_KEY

public static final java.lang.String MULTIPART_KEY

The request attributes key under which our multipart class is stored.

SERVLET_KEY

public static final java.lang.String SERVLET_KEY

The context attributes key under which we store the mapping defined for our controller serlet, which will be either a path-mapped pattern (/action/*) or an extension mapped pattern (*.do).

TRANSACTION_TOKEN_KEY

public static final java.lang.String TRANSACTION_TOKEN_KEY

The session attributes key under which our transaction token is stored, if it is used.

defaultLocale

protected static java.util.Locale defaultLocale

The system default Locale.

servlet

protected ActionServlet servlet

The controller servlet to which we are attached.

Constructor Detail

Action

public Action()

Method Detail

getServlet

public ActionServlet getServlet()

Return the controller servlet instance to which we are attached.

setServlet

public void setServlet(ActionServlet servlet)

Set the controller 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

perform

public ActionForward perform(ActionServlet servlet,
                             ActionMapping mapping,
                             ActionForm form,
                             javax.servlet.ServletRequest request,
                             javax.servlet.ServletResponse response)
                      throws java.io.IOException,
                             javax.servlet.ServletException

Deprecated. Use the new perform() method without a servlet argument

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

Parameters:

servlet - The ActionServlet instance owning this Action

mapping - The ActionMapping used to select this instance

actionForm - The optional ActionForm bean for this request (if any)

request - The servlet request we are processing

response - The servlet response we are processing

Throws:

java.io.IOException - if an input/output error occurs

javax.servlet.ServletException - if a servlet exception occurs

perform

public ActionForward perform(ActionMapping mapping,
                             ActionForm form,
                             javax.servlet.ServletRequest request,
                             javax.servlet.ServletResponse response)
                      throws java.io.IOException,
                             javax.servlet.ServletException

Process the specified non-HTTP request, and create the corresponding non-HTTP response (or forward to another web component that will create it). 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

actionForm - 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

Throws:

java.io.IOException - if an input/output error occurs

javax.servlet.ServletException - if a servlet exception occurs

perform

public ActionForward perform(ActionServlet servlet,
                             ActionMapping mapping,
                             ActionForm form,
                             javax.servlet.http.HttpServletRequest request,
                             javax.servlet.http.HttpServletResponse response)
                      throws java.io.IOException,
                             javax.servlet.ServletException

Deprecated. Use the new perform() method without a servlet argument

Process the specified HTTP request, and create the corresponding HTTP response (or forward to another web component that will create it). Return an ActionForward instance describing where and how control should be forwarded, or null if the response has already been completed.

Parameters:

servlet - The ActionServlet instance owning this Action

mapping - The ActionMapping used to select this instance

actionForm - The optional ActionForm bean for this request (if any)

request - The servlet request we are processing

response - The servlet response we are processing

Throws:

java.io.IOException - if an input/output error occurs

javax.servlet.ServletException - if a servlet exception occurs

perform

public ActionForward perform(ActionMapping mapping,
                             ActionForm form,
                             javax.servlet.http.HttpServletRequest request,
                             javax.servlet.http.HttpServletResponse response)
                      throws java.io.IOException,
                             javax.servlet.ServletException

Process the specified HTTP request, and create the corresponding HTTP response (or forward to another web component that will create it). 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

actionForm - The optional ActionForm bean for this request (if any)

request - The HTTP request we are processing

response - The HTTP response we are creating

Throws:

java.io.IOException - if an input/output error occurs

javax.servlet.ServletException - if a servlet exception occurs

generateToken

protected java.lang.String generateToken(javax.servlet.http.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

getLocale

protected java.util.Locale getLocale(javax.servlet.http.HttpServletRequest request)

Return the user's currently selected Locale.

Parameters:

request - The request we are processing

getResources

protected MessageResources getResources()

Return the message resources for this application.

isCancelled

protected boolean isCancelled(javax.servlet.http.HttpServletRequest request)

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

Parameters:

request - The servlet request we are processing

See Also:

CancelTag, ValidatingActionForm

isTokenValid

protected boolean isTokenValid(javax.servlet.http.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

resetToken

protected void resetToken(javax.servlet.http.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(javax.servlet.http.HttpServletRequest request,
                          ActionErrors errors)

Save the specified error messages keys into the appropriate request attribute for use by the <struts: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

saveToken

protected void saveToken(javax.servlet.http.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(javax.servlet.http.HttpServletRequest request,
                         java.util.Locale locale)

Set the user's currently selected Locale.

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

toHex

protected java.lang.String toHex(byte[] buffer)

Convert a byte array to a String of hexadecimal digits and return it.

Parameters:

buffer - The byte array to be converted