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edu.virtualschool.jwaa.GenericServlet Class Reference

Inheritance diagram for edu.virtualschool.jwaa.GenericServlet:

edu.virtualschool.jwaa.xml.JwaaServlet List of all members.

Detailed Description

Servlet provides the abstract protocol that concrete subclasses use to handle servlet requests.

Most of the work is done here. Subclasses must only override methods to return information particular to each site (e.g. the login page, default page, permission denied page, and so forth).

Copyright 2002 by Brad Cox: <bcox@virtualschool.edu>

Definition at line 27 of file GenericServlet.java.

Public Member Functions

 GenericServlet (MetaPage[] metaPages)
void doGet (HttpServletRequest req, HttpServletResponse rsp) throws ServletException, IOException
void doPost (HttpServletRequest req, HttpServletResponse rsp) throws ServletException, IOException
final void doRequest (HttpServletRequest req, HttpServletResponse rsp) throws IOException, ServletException
AccountAbstraction getAccountOrNull (HttpServletRequest req)
void logRequest (MetaPage meta, HttpServletRequest req, HttpServletResponse rsp)
MetaPage findMetaPage (String key)
abstract void doFault (MetaPage meta, HttpServletRequest req, HttpServletResponse rsp, Throwable e)
abstract AccountAbstraction getNullAccount ()
abstract MetaPage getDefaultPage ()
abstract MetaPage getRefusePage ()
abstract MetaPage getRootPage ()
final RequestDispatcher getRequestDispatcher (String path) throws IOFault

Package Attributes

final HashMap dispatchTable = new HashMap()

Static Package Attributes

Logger logger = Logger.getLogger(GenericServlet .class.getName())

Constructor & Destructor Documentation

edu.virtualschool.jwaa.GenericServlet.GenericServlet (  MetaPage[]  metaPages  ) 
 

Constructor This primes the dispatch table with a link for each of the dynamic pages they serve.

Parameters:
metaPages array of metaPages to be served by this servlet.

Definition at line 38 of file GenericServlet.java.

References edu.virtualschool.jwaa.GenericURI.getText(), and edu.virtualschool.jwaa.MetaPage.link. 

00039   {
00040     BasicConfigurator.configure();
00041     for (int i = 0; i < metaPages.length; i++)
00042     {
00043       MetaPage metaPage = metaPages[i];
00044       String url = metaPage.link.getText();
00045 
00046       MetaPage prior = (MetaPage)dispatchTable.get(url);
00047       if (prior != null)
00048         logger.error("Non-unique url: " + url + ". See \n" +
00049             " page "+metaPage+" and \n" +
00050             " page "+prior + "\n");
00051 
00052       dispatchTable.put(url, metaPage);
00053     }
00054   }

Member Function Documentation

abstract void edu.virtualschool.jwaa.GenericServlet.doFault (  MetaPage  meta,
HttpServletRequest  req,
HttpServletResponse  rsp,
Throwable  e
)  [pure virtual]
 

Applications must override to specify how to handle faults.

Parameters:
meta: the metapage of the target page
req: the servlet request parameters
rsp: servlet response parameters
e: the exception to report

Implemented in edu.virtualschool.jwaa.xml.JwaaServlet.

Referenced by edu.virtualschool.jwaa.GenericServlet.doRequest().

void edu.virtualschool.jwaa.GenericServlet.doGet (  HttpServletRequest  req,
HttpServletResponse  rsp
)  throws ServletException, IOException
 

Handle GET requests

Definition at line 58 of file GenericServlet.java.

References edu.virtualschool.jwaa.GenericServlet.doRequest(). 

00060   {
00061     doRequest(req, rsp);
00062   }

void edu.virtualschool.jwaa.GenericServlet.doPost (  HttpServletRequest  req,
HttpServletResponse  rsp
)  throws ServletException, IOException
 

Handle POST requests

Definition at line 66 of file GenericServlet.java.

References edu.virtualschool.jwaa.GenericServlet.doRequest(). 

00068   {
00069     doRequest(req, rsp);
00070   }

final void edu.virtualschool.jwaa.GenericServlet.doRequest (  HttpServletRequest  req,
HttpServletResponse  rsp
)  throws IOException, ServletException
 

Handle get or post servlet requests by parsing out the requested page id from request.getPathInfo().

Parameters:
req: the http servlet request object
rsp: the http servlet response object
Exceptions:
ServletException 
IOException 

Definition at line 80 of file GenericServlet.java.

References edu.virtualschool.jwaa.MetaPage.allowsAccessBy(), edu.virtualschool.jwaa.GenericServlet.doFault(), edu.virtualschool.jwaa.GenericServlet.findMetaPage(), edu.virtualschool.jwaa.GenericServlet.getAccountOrNull(), edu.virtualschool.jwaa.GenericServlet.getRefusePage(), edu.virtualschool.jwaa.GenericPage.init(), edu.virtualschool.jwaa.GenericServlet.logRequest(), edu.virtualschool.jwaa.MetaPage.pageClass, and edu.virtualschool.jwaa.GenericPage.run().

Referenced by edu.virtualschool.jwaa.GenericServlet.doGet(), and edu.virtualschool.jwaa.GenericServlet.doPost(). 

00082   {
00083     AccountAbstraction person = getAccountOrNull(req);
00084     String uri = req.getRequestURI();
00085     MetaPage meta = findMetaPage(uri);
00086     logRequest(meta, req, rsp);
00087     if (!meta.allowsAccessBy(person))
00088         meta = getRefusePage();
00089     try
00090     {
00091       GenericPage page = (GenericPage)meta.pageClass.newInstance();
00092       page.init(meta, this, req, rsp);
00093       page.run();
00094     }
00095     catch (IgnorableFault e)
00096     {
00097     }
00098     catch (IOFault e)
00099     {
00100       doFault(meta, req, rsp, e);
00101       throw (IOException)e.getChainedException();
00102     }
00103     catch (IOException e)
00104     {
00105       doFault(meta, req, rsp, e);
00106       throw e;
00107     }
00108     catch (ServletException e)
00109     {
00110       doFault(meta, req, rsp, e);
00111       throw e;
00112     }
00113     catch (Throwable e)
00114     {
00115       doFault(meta, req, rsp, e);
00116     }
00117   }

MetaPage edu.virtualschool.jwaa.GenericServlet.findMetaPage (  String  key  ) 
 

Find a page in the servlet's dispatch table. This is declared non-final so subclasses can override it for specialized needs. By default, the lookup key is the uri as returned by request.getURI(). Returns getMetaPage() if the lookup fails, so this NEVER returns null.

Parameters:
key 
Returns:

Definition at line 165 of file GenericServlet.java.

References edu.virtualschool.jwaa.GenericServlet.getDefaultPage().

Referenced by edu.virtualschool.jwaa.GenericServlet.doRequest(). 

00166   {
00167     Object o = dispatchTable.get(key);
00168     MetaPage meta = (MetaPage)o;
00169     if (meta == null)
00170       meta = getDefaultPage(); 
00171     return meta;
00172   }

AccountAbstraction edu.virtualschool.jwaa.GenericServlet.getAccountOrNull (  HttpServletRequest  req  ) 
 

Returns the currently logged in Account if someone is logged in (e.g. if a session exists and contains an person attribute), else null.

Parameters:
req: the http servlet request object
Returns:

Definition at line 125 of file GenericServlet.java.

Referenced by edu.virtualschool.jwaa.GenericServlet.doRequest(). 

00126   {
00127     HttpSession session = req.getSession();
00128     if (session == null)
00129       return null;
00130     AccountAbstraction person = (AccountAbstraction) session.getAttribute(GenericPage.SESSION_ATTRIBUTE_NAME);
00131     if (person == null)
00132       return null;
00133     else
00134       return person;
00135   }

abstract MetaPage edu.virtualschool.jwaa.GenericServlet.getDefaultPage (   )  [pure virtual]
 

Override to specify the page to show if a page lookup fails.

Returns:
PageElement

Implemented in edu.virtualschool.jwaa.xml.JwaaServlet.

Referenced by edu.virtualschool.jwaa.GenericServlet.findMetaPage().

abstract AccountAbstraction edu.virtualschool.jwaa.GenericServlet.getNullAccount (   )  [pure virtual]
 

This method gives the application control over what getAccount returns when no one is logged in. Applications often define their own conventions that are inconsistent with any decision hardcoded at this level.

Returns:
AccountAbstraction

Implemented in edu.virtualschool.jwaa.xml.JwaaServlet.

Referenced by edu.virtualschool.jwaa.GenericPage.getAccount(), and edu.virtualschool.jwaa.GenericPage.setAccount().

abstract MetaPage edu.virtualschool.jwaa.GenericServlet.getRefusePage (   )  [pure virtual]
 

Override with the page to show if a page access is refused.

Returns:
PageElement

Implemented in edu.virtualschool.jwaa.xml.JwaaServlet.

Referenced by edu.virtualschool.jwaa.GenericServlet.doRequest().

final RequestDispatcher edu.virtualschool.jwaa.GenericServlet.getRequestDispatcher (  String  path  )  throws IOFault
 

This Dispatcher rigamarole has been problematic from day one. Apparently path must be the full path minus the leading (context name) component. Why: who knows?

Parameters:
path: The full path (/context required)
Returns:
RequestDispatcher: A dispatcher capable of forwarding requests to, or including text from, the servlet specified by that path.
Exceptions:
IOFault if the path does not begin with "/" or if the RequestDispatcher still can't be found (should not happen).

Definition at line 246 of file GenericServlet.java. 

00247   {
00248     if (!path.startsWith("/"))
00249       throw new IOFault("" + path + " does not begin with \"/\"");
00250     else
00251     {
00252       int i = path.indexOf("/", 1);
00253       if (i < 0)
00254         throw new IOFault("" + path + " does not begin with \"/contextName/\"");
00255 
00256       String pathInContext = path.substring(i);
00257       ServletContext servletContext = getServletContext();
00258       RequestDispatcher dispatcher =
00259         servletContext.getRequestDispatcher(pathInContext);
00260 
00261       if (dispatcher == null)
00262         throw new IOFault(
00263           "" + this +".getRequestDispatcher: " + path + " failed");
00264       return dispatcher;
00265     }
00266   }

abstract MetaPage edu.virtualschool.jwaa.GenericServlet.getRootPage (   )  [pure virtual]
 

Override to return the root page of the page hierarchy. The reference to the root of the hierarchy will cause the classloader to load all other pages in the hierarchy. If you have any pages that are not in the hierarchy, they will not be loaded.

Returns:
PageElement

Implemented in edu.virtualschool.jwaa.xml.JwaaServlet.

void edu.virtualschool.jwaa.GenericServlet.logRequest (  MetaPage  meta,
HttpServletRequest  req,
HttpServletResponse  rsp
) 
 

Called on each dispatch to log the request. Subclases can override this to do custom logging.

Parameters:
meta 
req 
rsp 

Definition at line 143 of file GenericServlet.java.

Referenced by edu.virtualschool.jwaa.GenericServlet.doRequest(). 

00144   {
00145     if (logger.isDebugEnabled())
00146     {
00147       logger.debug("request: "+req.getClass().getName());
00148       logger.debug("  contextPath:    "+req.getContextPath());
00149       logger.debug("  servletPath:    "+req.getServletPath());
00150       logger.debug("  pathInfo:       "+req.getPathInfo());
00151       logger.debug("  queryString:    "+req.getQueryString());
00152       logger.debug("  requestURI:     "+req.getRequestURI());
00153       logger.debug("  page:           "+meta);
00154     }
00155   }

The documentation for this class was generated from the following file: