net.sf.ewc
Class EasyWebController

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          net.sf.ewc.EasyWebController

All Implemented Interfaces:

java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public class EasyWebController

extends javax.servlet.http.HttpServlet

EasyWebControlleris the EWC controller servlet. Its main responsability is performing user changes on the model, and calling the user event method after those changes.

Servlet operations

This controller servlet goes through the following stages on each request:

• Apply model changes: The user changes form fields and compoenent visual states. In this stage, every change is performed on the model, driving the application to a new state.
• Path processing: If the user has thrown an event (sometimes a request doesn't include event because it is just a visual refresh), the handler method in the context class is invocated. This leads to a new application state, that will be the state to be rendered in the presentation stage.
• Presentation page selection: Depending on the value returned by the event handler method, a presentation page is selected. Once it has been selected, a forward is dispatched to that presentation page.

Accepted POST/GET parameters

Every parameter whose name has been formed with EWCSession.getFullExpression(Object,String)will be handled as a model change. This method is called by taglibs to write well formed parameter names, but can be called directly on a JSP.

There are three special parameters that this servlet accepts:

• EWC_PROCESS_GET_PARAMETER: 'true' to process.
• EWC_MODEL_CHANGES_PARAMETER: That can contain a CSV secuence of model changes in the same way that usual parameters.
• EWC_EVENT_PARAMETER: That contains the user event and that must be well formed using EWCSession.getEventFullExpression(String, String).
• EWC_DEFAULT_CONTEXT_PARAMETER: Default context for those model changes that doesn't specify their context.

After the model changes and event processing stages, the control flow is redirected to presentation. The presentation page will be selected on the following basis:

• If the event method invocation returned an String, it will be interpreted as the URI to the next presentation page.
• If the event method invocation returned void, the path info (URL substring begining after the servlet path) will be interpreted as the URI to the next page.

Initialization/configuration parameters

This servlet can be configured with the following initialization parameters:

• Value of LOG_FILE: Log file.
• Value of LOG_LEVEL: Log level (ERROR, WARNING, INFO, FINE, FINER, FINEST).
• Value of UPLOAD_THRESHOLD: Uploaded files with a size below this threshold will be stored in a memory buffer, improving file upload performance.
• Value of UPLOAD_MAX_SIZE: Uploaded files with a size greater than this value will not be accepted.

Author:

mballesteros

See Also:

Serialized Form

Field Summary

static java.lang.String	EWC_DEFAULT_CONTEXT_PARAMETER Default context parameter
static java.lang.String	EWC_EVENT_PARAMETER The parameter that contains the method to execute after model changes
static java.lang.String	EWC_MODEL_CHANGES_PARAMETER Compact model changes parameter.
static java.lang.String	EWC_PROCESS_GET_PARAMETER True to process GET
static java.lang.String	EWC_REQUEST_URI_ATTRIBUTE Request attribute where the original request URI is stored
static java.lang.String	FILEUPLOAD_CONTEXT_ATTRIBUTE File upload context attribute.
static java.lang.String	LOG_FILE Log file initialization parameter name
static java.lang.String	LOG_LEVEL Log level initialization parameter name
static java.lang.String	UPLOAD_MAX_SIZE Upload maximum size initialization parameter name
static java.lang.String	UPLOAD_THRESHOLD Upload threshold initialization parameter name

Constructor Summary

EasyWebController()

Method Summary

void	doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) GET requests are redirected to the root application context, except when EWC_PROCESS_GET_PARAMETERequals 'true' (this allows you to pass parameters through URL).
void	doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) Processes user requests...
void	init() Servlet initialization.
static void	setConsoleLog(java.lang.String level) Sets a console log
static void	setFileLog(java.lang.String logfile, java.lang.String level) Sets a file log
static void	setLog(java.util.logging.Handler handler, java.lang.String level) Sets the package log

Methods inherited from class javax.servlet.http.HttpServlet

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

Methods inherited from class javax.servlet.GenericServlet

destroy, 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

EWC_PROCESS_GET_PARAMETER

public static final java.lang.String EWC_PROCESS_GET_PARAMETER

True to process GET

See Also:

Constant Field Values

EWC_DEFAULT_CONTEXT_PARAMETER

public static final java.lang.String EWC_DEFAULT_CONTEXT_PARAMETER

Default context parameter

See Also:

Constant Field Values

EWC_MODEL_CHANGES_PARAMETER

public static final java.lang.String EWC_MODEL_CHANGES_PARAMETER

Compact model changes parameter. This parameter can contain a CSV secuence of changes to be done on the model.

See Also:

Constant Field Values

EWC_EVENT_PARAMETER

public static final java.lang.String EWC_EVENT_PARAMETER

The parameter that contains the method to execute after model changes

See Also:

Constant Field Values

EWC_REQUEST_URI_ATTRIBUTE

public static final java.lang.String EWC_REQUEST_URI_ATTRIBUTE

Request attribute where the original request URI is stored

See Also:

Constant Field Values

LOG_FILE

public static final java.lang.String LOG_FILE

Log file initialization parameter name

See Also:

Constant Field Values

LOG_LEVEL

public static final java.lang.String LOG_LEVEL

Log level initialization parameter name

See Also:

Constant Field Values

UPLOAD_THRESHOLD

public static final java.lang.String UPLOAD_THRESHOLD

Upload threshold initialization parameter name

See Also:

Constant Field Values

UPLOAD_MAX_SIZE

public static final java.lang.String UPLOAD_MAX_SIZE

Upload maximum size initialization parameter name

See Also:

Constant Field Values

FILEUPLOAD_CONTEXT_ATTRIBUTE

public static final java.lang.String FILEUPLOAD_CONTEXT_ATTRIBUTE

File upload context attribute. This will be the name of the attribute (in the servlet context) where the FileUpload component will be placed in.

Constructor Detail

EasyWebController

public EasyWebController()

Method Detail

init

public void init()

Servlet initialization. Prepares a temporal dir for file upload

setFileLog

public static void setFileLog(java.lang.String logfile,
                              java.lang.String level)
                       throws java.lang.SecurityException,
                              java.io.IOException

Sets a file log

Parameters:

logfile -

level -

Throws:

java.lang.SecurityException

java.io.IOException

setConsoleLog

public static void setConsoleLog(java.lang.String level)

Sets a console log

Parameters:

level -

setLog

public static void setLog(java.util.logging.Handler handler,
                          java.lang.String level)

Sets the package log

Parameters:

handler -

level -

doGet

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

GET requests are redirected to the root application context, except when EWC_PROCESS_GET_PARAMETERequals 'true' (this allows you to pass parameters through URL). Images, css, and other files requested by the client browser using GET method are processed by the default servlet container as direct requests to the root application context.

Parameters:

request - The servlet request

response - The servlet response

Throws:

javax.servlet.ServletException - Thrown if the requested file cannot be found

java.io.IOException - Thrown if there's an I/O problem

doPost

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

Processes user requests...

Parameters:

request -

response -

Throws:

javax.servlet.ServletException

java.io.IOException