org.josef.web.servlet

Class AbstractHttpServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

org.josef.web.servlet.AbstractHttpServlet

All Implemented Interfaces:

Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

Direct Known Subclasses:

AbstractCsvServlet, EchoParameterServlet, HelloWorldServlet, TimeConsumingServlet

public abstract class AbstractHttpServlet
extends javax.servlet.http.HttpServlet

Base class for all HTTP based servlets.
This class adds timing and logging to servlets and makes sure that active requests are finished before a shutdown of the servlet runner.

Version:

1.1 $Revision: 6483 $

Author:

Kees Schotanus

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AbstractHttpServlet()

Method Summary

Modifier and Type	Method and Description
static void	clearSessionData(javax.servlet.http.HttpSession session) Clears all data from the supplied session.
void	destroy() Called by the servlet runner when this servlet has to be destroyed.
protected int	getActiveRequests() Gets the number of active requests.
protected Locale	getLocale(javax.servlet.http.HttpServletRequest request) Gets the locale.
protected String	getRequiredInitParameter(String parameterName) Gets a required initialization parameter.
String	getServletInfo() Returns information about the servlet.
static String	getSessionInfo(javax.servlet.http.HttpServletRequest request) Gets the session information from the supplied request and converts it to a single string.
void	service(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) A wrapper around the service method to do some housekeeping chores like time measurement and keeping track of active requests. It is guaranteed by the Servlet specifications that this method will not be called when the Servlet container is in the process of shutting down.

Methods inherited from class javax.servlet.http.HttpServlet

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

Methods inherited from class javax.servlet.GenericServlet

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

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractHttpServlet

public AbstractHttpServlet()

Method Detail

getActiveRequests

protected int getActiveRequests()

Gets the number of active requests.

Returns:

The number of active requests.

service

public void service(javax.servlet.http.HttpServletRequest request,
                    javax.servlet.http.HttpServletResponse response)
             throws IOException,
                    javax.servlet.ServletException

A wrapper around the service method to do some housekeeping chores like time measurement and keeping track of active requests.
It is guaranteed by the Servlet specifications that this method will not be called when the Servlet container is in the process of shutting down.

Overrides:

service in class javax.servlet.http.HttpServlet

Parameters:

request - The HttpServletRequest.

response - The HttpServletResponse.

Throws:

IOException - When an error occurs while writing to the PrintStream of the supplied response object.

javax.servlet.ServletException - When a subclass throws this exception.

getLocale

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

Gets the locale.
When a locale cookie is present, the locale of the cookie is used, when the locale cookie is absent the locale of the supplied request is used.

Parameters:

request - The request.

Returns:

The locale.

destroy

public void destroy()

Called by the servlet runner when this servlet has to be destroyed.
Prevents the servlet runner from destroying this servlet when it is actively servicing requests.

Specified by:

destroy in interface javax.servlet.Servlet

Overrides:

destroy in class javax.servlet.GenericServlet

getServletInfo

public String getServletInfo()

Returns information about the servlet.

Specified by:

getServletInfo in interface javax.servlet.Servlet

Overrides:

getServletInfo in class javax.servlet.GenericServlet

Returns:

Servlet info.

getRequiredInitParameter

protected String getRequiredInitParameter(String parameterName)
                                   throws javax.servlet.UnavailableException

Gets a required initialization parameter.
You can still use: GenericServlet.getInitParameter(String) for optional init parameters.
Note: Preferably call this method from within an init(...) method since the UnavailableException that could be thrown is used by the init(...) method to notify the user that the servlet is not available.

Parameters:

parameterName - Name of the required init parameter.

Returns:

Value belonging to the parameter.

Throws:

javax.servlet.UnavailableException - When the init parameter is missing or when the parameter value is null.

getSessionInfo

public static String getSessionInfo(javax.servlet.http.HttpServletRequest request)

Gets the session information from the supplied request and converts it to a single string.

Parameters:

request - The request.

Returns:

Session information as key=...,value=...:key=...,value=... or an empty String when the session does not contain any data or "Invalid session!" when the session is invalid.

Throws:

NullPointerException - When the supplied request is null.

clearSessionData

public static void clearSessionData(javax.servlet.http.HttpSession session)

Clears all data from the supplied session.
Note: this method clears data from the session but keeps the session itself valid, hence it is more gentle than session.invalidate().

Parameters:

session - HttpSession to clear.

Throws:

NullPointerException - When the supplied session is null.