com.simpleservlets.pageprocessor
Class PageProcessor

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          com.simpleservlets.pageprocessor.PageProcessor

All Implemented Interfaces:

Serializable, Servlet, ServletConfig

public abstract class PageProcessor
extends HttpServlet

This abstract class is subclassed by the application-specific class where the abstract setup() method is implemented. If any shutdown tasks need to be done, override the shutdown() method. The init(), destroy, doPost(), and doGet() methods are rarely overridden (and if any of these are overridden, care must be taken to avoid breaking PageProcessor.

Author:

Paul Hyde

See Also:

Serialized Form

Field Summary

static String	ERROR_PAGE_NAME Reserved page name for the error page.
static String	RELOAD_PAGE_NAME Reserved page name for the "reload warning" page.

Constructor Summary

protected

PageProcessor()

Method Summary

void	addPage(PageHandler handler, String pageName) Add a PageHandler and associate it with the specified page name.
void	destroy() Generally this should not be overridden in subclasses—use shutdown() instead.
protected void	doGet(HttpServletRequest req, HttpServletResponse res) Generally this should not be overridden in subclasses—use PageHandler instead.
protected void	doHeadCustom(HttpServletRequest req, HttpServletResponse resp) Generally this should not be overridden in subclasses—use PageHandler instead.
protected void	doPost(HttpServletRequest req, HttpServletResponse res) Generally this should not be overridden in subclasses—use PageHandler instead.
PageHandler	getErrorPage() Returns the page handler designated as the error page.
PageHandler	getFrontPage() Returns the page handler designated as the front page.
String	getFrontPageName() Returns the name of the front page, or null if no front page has been specified yet.
ValueMap	getInitValues() A mapping of all the web-app initialization parameters.
PageHandler	getPage(String pageName) Returns the page handler for the page with the specified name.
PageHandler	getPage(String pageName, Class<? extends PageHandler> pageType) Returns the page handler for the page with the specified name.
String	getPageName(PageHandler handler) Returns the name that was associated with the specified PageHandler.
ReloadPageHandler	getReloadPage() Returns the page handler designated for reload/refresh attempts.
InputStream	getResourceAsStream(String pathToResource) Retrieves a stream to a resource typically in the web-app context, typically from a file in a WAR-file.
ValueMap	getResourceAsValueMap(String pathToResource) Creates a ValueMap from a resource typically in the web-app context, typically from a file in a WAR-file.
protected Session.Manager	getSessionManager()
void	init() Generally this should not be overridden in subclasses—use setup() instead.
boolean	isFrontPageAvailable() Returns true if there is a front page stored.
boolean	isPageAvailable(String pageName) Returns true if there is a page stored for the specified page name.
void	setErrorPage(PageHandler handler) Indicates the page to use when an uncaught exception occurs.
void	setFrontPage(PageHandler handler, String pageName) Add a PageHandler and associate it with the specified page name.
void	setReloadPage(ReloadPageHandler handler) Indicates the page to use when the user presses reload/refresh.
abstract void	setup() Implemented by subclasses to configure initial settings.
void	showReloadPage(PageContext pc) Requests that the reload/refresh warning page be shown.
void	showReloadPage(PageContext pc, String continuePage) Requests that the reload/refresh warning page be shown.
void	shutdown() Called from the destroy() method of the servlet.

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

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

Field Detail

ERROR_PAGE_NAME

public static final String ERROR_PAGE_NAME

Reserved page name for the error page. This name must be used as the only name for the error page for PageProcessor to function correctly. Also, no other page may use this reserved page name. The name of this page is always: "PageProcessorErrorPage".

See Also:

Constant Field Values

RELOAD_PAGE_NAME

public static final String RELOAD_PAGE_NAME

Reserved page name for the "reload warning" page. This name must be used as the only name for the reload page for PageProcessor to function correctly. Also, no other page may use this reserved page name. The name of this page is always: "PageProcessorReloadPage".

See Also:

Constant Field Values

Constructor Detail

PageProcessor

protected PageProcessor()

Method Detail

setup

public abstract void setup()
                    throws PageProcessorException

Implemented by subclasses to configure initial settings. Called one time—before any page requests are serviced (called at the end of the servlet's init() method). Both getInitValues() and getSessionManager() may be safely called from within setup().

Throws:

PageProcessorException

getInitValues

public ValueMap getInitValues()

A mapping of all the web-app initialization parameters.

getResourceAsStream

public InputStream getResourceAsStream(String pathToResource)
                                throws PageProcessorException

Retrieves a stream to a resource typically in the web-app context, typically from a file in a WAR-file. Path usually begins with "/", but this is not required.

See IOTools.getInputStreamForResource(String) as a more direct way of getting a stream. During initialization, PageProcessor registers itself as a IOTools.ServletResourceLocator with IOTools.

Throws:

PageProcessorException - if the specified resource can not be found in the web-app context.

getResourceAsValueMap

public ValueMap getResourceAsValueMap(String pathToResource)
                               throws PageProcessorException

Creates a ValueMap from a resource typically in the web-app context, typically from a file in a WAR-file. Path usually begins with "/", but this is not required.

See ValueMap.createFromResource(String) as a more direct way of getting a map. During initialization, PageProcessor registers itself as a IOTools.ServletResourceLocator with IOTools.

Throws:

PageProcessorException - if the resource does not exist or if there are problems reading from the specified file.

getSessionManager

protected Session.Manager getSessionManager()

setFrontPage

public void setFrontPage(PageHandler handler,
                         String pageName)

Add a PageHandler and associate it with the specified page name. This page will also be marked as the "front page". The "front page" is returned for unknown page names and when no page name is specified.

isFrontPageAvailable

public boolean isFrontPageAvailable()

Returns true if there is a front page stored.

getFrontPage

public PageHandler getFrontPage()
                         throws PageProcessorException

Returns the page handler designated as the front page.

Throws:

PageProcessorException - if no front page has been set.

getFrontPageName

public String getFrontPageName()

Returns the name of the front page, or null if no front page has been specified yet.

setErrorPage

public void setErrorPage(PageHandler handler)

Indicates the page to use when an uncaught exception occurs. If this method is never called, or if null is passed in, GenericErrorPage is used. There is always an error page defined.

getErrorPage

public PageHandler getErrorPage()

Returns the page handler designated as the error page.

setReloadPage

public void setReloadPage(ReloadPageHandler handler)

Indicates the page to use when the user presses reload/refresh. If this method is never called, or if null is passed in, GenericReloadPage is used. There is always a reload page defined.

getReloadPage

public ReloadPageHandler getReloadPage()

Returns the page handler designated for reload/refresh attempts.

showReloadPage

public void showReloadPage(PageContext pc)
                    throws PageProcessorException

Requests that the reload/refresh warning page be shown.

Throws:

PageProcessorException

showReloadPage

public void showReloadPage(PageContext pc,
                           String continuePage)
                    throws PageProcessorException

Requests that the reload/refresh warning page be shown. The continuePage indicates the page that the "no reload" page should provide a link to for the user to "continue" on to after reading the warning.

Parameters:

pc - context of the current request/response cycle

continuePage - the page to link to from the warning page. If null is passed in, then the link will be to the original requested page that was part of the reload triggering.

Throws:

PageProcessorException

addPage

public void addPage(PageHandler handler,
                    String pageName)

Add a PageHandler and associate it with the specified page name.

isPageAvailable

public boolean isPageAvailable(String pageName)

Returns true if there is a page stored for the specified page name.

getPage

public PageHandler getPage(String pageName,
                           Class<? extends PageHandler> pageType)
                    throws PageProcessorException

Returns the page handler for the page with the specified name.

Throws:

PageProcessorException - if no page with that name can be found, or if the page found does not match the pageType specified.

getPage

public PageHandler getPage(String pageName)
                    throws PageProcessorException

Returns the page handler for the page with the specified name.

Throws:

PageProcessorException - if no page with that name can be found.

getPageName

public String getPageName(PageHandler handler)
                   throws PageProcessorException

Returns the name that was associated with the specified PageHandler.

Parameters:

handler - to look up name for

Returns:

the name associated with the specified handler

Throws:

PageProcessorException - if no name has been associated, or if 2+ names were associated with the same handler.

shutdown

public void shutdown()

Called from the destroy() method of the servlet. Default implementation does nothing, override if any specific cleanup must be done.

init

public void init()
          throws ServletException

Generally this should not be overridden in subclasses—use setup() instead. If in a rare case this method does need to be overridden, be sure to call super.init() first.

Overrides:

init in class GenericServlet

Throws:

ServletException

destroy

public void destroy()

Generally this should not be overridden in subclasses—use shutdown() instead. If in a rare case this method does need to be overridden, be sure to call super.destory() first.

Specified by:

destroy in interface Servlet

Overrides:

destroy in class GenericServlet

doGet

protected void doGet(HttpServletRequest req,
                     HttpServletResponse res)
              throws ServletException,
                     IOException

Generally this should not be overridden in subclasses—use PageHandler instead.

Overrides:

doGet in class HttpServlet

Throws:

ServletException

IOException

doHeadCustom

protected void doHeadCustom(HttpServletRequest req,
                            HttpServletResponse resp)
                     throws ServletException,
                            IOException

Generally this should not be overridden in subclasses—use PageHandler instead. This implementation overrides the default in HttpServlet and does NOT call doGet()!

Throws:

ServletException

IOException

doPost

protected void doPost(HttpServletRequest req,
                      HttpServletResponse res)
               throws ServletException,
                      IOException

Generally this should not be overridden in subclasses—use PageHandler instead.

Overrides:

doPost in class HttpServlet

Throws:

ServletException

IOException