com.jcorporate.expresso.core.servlet
Class StdServlet

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          com.jcorporate.expresso.core.servlet.StdServlet

All Implemented Interfaces:

Serializable, Servlet, ServletConfig

Direct Known Subclasses:

DBServlet

public abstract class StdServlet

extends HttpServlet

A Servlet base class adding some basic common functionality to the core HttpServlet class.

Author:

Michael Nash

See Also:

DBServlet, Serialized Form

Field Summary

protected String	mySchema
protected static String	thisClass

Constructor Summary

StdServlet()

Method Summary

void	destroy() Called when the web context is destroyed or reloaded
void	doGet(HttpServletRequest request, HttpServletResponse response) Ancestor calls this function (with super.doGet) to handle making database connection, getting user login info and other common tasks.
void	doPost(HttpServletRequest req, HttpServletResponse res) Ancestor calls this method via super.doPost to handle standard operations.
protected String	getSchema() Return the name of the schema class that this servlet is registered within
protected String	getServerName(HttpServletRequest request) Return the name of the current web server system
int	getServerPort(HttpServletRequest request) Return the port number the servlet runtime engine is running on
String	getServletPrefix(HttpServletRequest request) Return a string to be used as part of the URL to call this servlet.
String	getServletPrefix(HttpServletRequest request, String servlet)
String	getString(HttpServletRequest req, String stringCode) Convenience method to request a localized message with no parameters
String	getString(HttpServletRequest req, String stringCode, Object[] args) Pass on a call to retrieve an appropriate localized string from the correct Schema object
String	getTitle() Ancestors of this class override this method to return a specific title that is used by the security administration Controllers to describe the servlet
protected void	handleParam(HttpServletRequest request, HttpServletResponse response) Handle the parameters to this servlet & set up standard information
void	init(ServletConfig sc) Servlet initialization.
protected void	setSchema(String schemaClass) Tell this StdServlet object what Schema it belongs to.
protected void	showError(String errorMessage, HttpServletRequest request, HttpServletResponse response) Display an error to the user in a nicely formatted manner
protected void	showError(Throwable t, HttpServletRequest request, HttpServletResponse response) Display a throwable (like an exception) to the user in a nicely formatted manner.

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

thisClass

protected static final String thisClass

mySchema

protected String mySchema

Constructor Detail

StdServlet

public StdServlet()

Method Detail

doGet

public void doGet(HttpServletRequest request,
                  HttpServletResponse response)
           throws ServletException,
                  IOException

Ancestor calls this function (with super.doGet) to handle making database connection, getting user login info and other common tasks.

Parameters:

request - Standard request object

response - Standard response object

Throws:

ServletException - If an uncaught exception occurs

IOException - If an I/O error occurs while communicating with the client

doPost

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

Ancestor calls this method via super.doPost to handle standard operations.

Parameters:

req - Standard request object

res - Standard response object

Throws:

ServletException - If an uncaught exception occurs

IOException - If an I/O error occurs while communicating with the client

getServerName

protected String getServerName(HttpServletRequest request)

Return the name of the current web server system

Parameters:

request -

Returns:

String The name of the current web server

getServerPort

public int getServerPort(HttpServletRequest request)

Return the port number the servlet runtime engine is running on

Parameters:

request -

Returns:

int The port number for servlets

getServletPrefix

public String getServletPrefix(HttpServletRequest request)
                        throws ServletException

Return a string to be used as part of the URL to call this servlet. Often used by doGet methods to build the action for a form to call the doPost method of the same servlet.

Parameters:

request -

Returns:

String The string for building a URL

Throws:

ServletException - If the string cannot be built due to setup information not being available

getServletPrefix

public String getServletPrefix(HttpServletRequest request,
                               String servlet)
                        throws ServletException

Parameters:

request -

servlet -

Returns:

Throws:

ServletException

getTitle

public String getTitle()

Ancestors of this class override this method to return a specific title that is used by the security administration Controllers to describe the servlet

Returns:

handleParam

protected void handleParam(HttpServletRequest request,
                           HttpServletResponse response)
                    throws IOException,
                           ServletException

Handle the parameters to this servlet & set up standard information

Parameters:

request - Standard request object

response - Standard response object

Throws:

IOException - If an I/O error occurs communicating with the client

ServletException - If an uncaught exception occurs

showError

protected void showError(String errorMessage,
                         HttpServletRequest request,
                         HttpServletResponse response)
                  throws ServletException

Display an error to the user in a nicely formatted manner

Parameters:

errorMessage - Error message

request -

response -

Throws:

ServletException

showError

protected void showError(Throwable t,
                         HttpServletRequest request,
                         HttpServletResponse response)
                  throws ServletException

Display a throwable (like an exception) to the user in a nicely formatted manner. Also show the stack trace in an HTML comment

Parameters:

t - The throwable error

request -

response -

Throws:

ServletException

init

public void init(ServletConfig sc)
          throws ServletException

Servlet initialization. Checks to make sure ConfigManager has been initialized and starts the configuration process if it hasn't.

Parameters:

sc - The ServletConfig. Should contain 'configDir' as a context parameter, and possibly 'logDir'.

Throws:

ServletException

destroy

public void destroy()

Called when the web context is destroyed or reloaded

setSchema

protected void setSchema(String schemaClass)

Tell this StdServlet object what Schema it belongs to. This is used when the Controller tries to use it's "getString(String, Object[])" method to prepare internationalized messages - it passes the call along to the appropriate schema which knows how to locate the proper message file

Parameters:

schemaClass -

getString

public String getString(HttpServletRequest req,
                        String stringCode,
                        Object[] args)
                 throws ServletException

Pass on a call to retrieve an appropriate localized string from the correct Schema object

Parameters:

req -

stringCode -

args -

Returns:

Throws:

ServletException

getString

public String getString(HttpServletRequest req,
                        String stringCode)
                 throws ServletException

Convenience method to request a localized message with no parameters

Parameters:

req -

stringCode -

Returns:

Throws:

ServletException

getSchema

protected String getSchema()

Return the name of the schema class that this servlet is registered within

Returns: