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Andrew Petro

Andrew Petro

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...

We

need

to

look

carefully

at

the

"object"

argument.

The

object

here

is

a

Command.

LoginController

extends

SimpleFormController

which

extends

AbstractFormController

which

extends

BaseCommandController

which

extends

AbstractController

which

extends

WebContentGenerator

which

extends

WebApplicationObjectSupport

which

extends

ApplicationObjectSupport.

In

Spring

Web

MVC

FormControllers,

the

forms

play

the

role

of

"commands"

in

the

more

general

CommandController

model.

So,

in

AbstractController

there

is

a

final

method

handleRequest():

{

Panel
bgColor#FFFFCE
titleWhere is the object coming from?
borderStylesolid
Wiki Markup
:= }
Code Block
title
AbstractController
handleRequest()
public final ModelAndView handleRequest(HttpServletRequest request, HttpServletResponse response)
			throws Exception {

		// delegate to WebContentGenerator for checking and preparing
		checkAndPrepare(request, response, this instanceof LastModified);

		// execute in synchronized block if required
		if (this.synchronizeOnSession) {
			HttpSession session = request.getSession(false);
			if (session != null) {
				synchronized (session) {
					return handleRequestInternal(request, response);
				}
			}
		}
		
		return handleRequestInternal(request, response);
	}
{code}

As

we

can

see

here,

it

delegates

to

the

method

handleRequestInternal(),

which

is

declared

to

be

abstract:

{

|= }
Code Block
title
AbstractController
handleRequestInternal()
/**
	 * Template method. Subclasses must implement this.
	 * The contract is the same as for handleRequest.
	 * @see #handleRequest
	 */
	protected abstract ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response)
	    throws Exception;

{code}

LoginController

defaults

this

Command

class:

{

:= }
Code Block
title
LoginController
afterPropertiesSet()
excerpt
  public void afterPropertiesSet() throws Exception {

        if (this.getCommandClass() == null) {
            this.setCommandName("credentials");
            this.setCommandClass(UsernamePasswordCredentials.class);
{code}


In

In BaseCommandController,

we

have:

{

:= }
Code Block
title
BaseCommandController
getCommand()
/**
 * Retrieve a command object for the given request.
 * <p>Default implementation calls createCommand. Subclasses can override this.
 * @param request current HTTP request
 * @return object command to bind onto
 * @see #createCommand
 */
 protected Object getCommand(HttpServletRequest request) throws Exception {
    return createCommand();
 }
{code}

And

the

createCommand()

method

to

which

it

delegates:

{

:= }
Code Block
title
BaseCommandController
createCommand()
/**
 * Create a new command instance for the command class of this controller.
 * @return the new command instance
 * @throws InstantiationException if the command class could not be instantiated
 * @throws IllegalAccessException if the class or its constructor is not accessible
 */
 protected final Object createCommand() throws InstantiationException, IllegalAccessException {
    if (this.commandClass == null) {
         throw new IllegalStateException("Cannot create command without commandClass being set - " +
            "either set commandClass or override formBackingObject");
    }
    if (logger.isDebugEnabled()) {
        logger.debug("Creating new command of class [" + this.commandClass.getName() + "]");
    }
    return this.commandClass.newInstance();
 } {code}
Code Block
titleCurrent CredentialsBinder interface
/**
 * Interface for a class that can bind items stored in the request to a particular
 * credentials implementation.  This allows for binding beyond the basic
 * JavaBean/Request parameter binding that is handled by Spring automatically.
 */
public interface CredentialsBinder {
    /**
    * Method to allow manually binding attributes from the request object to properties of
    * the credentials.  Useful when there is no mapping of attribute to property for the 
    * usual Spring binding to handle.
    * 
    * @param request The HttpServletRequest from which we wish to bind credentials to
    * @param credentials The credentials we will be doing custom binding to.
    */
    void bind(HttpServletRequest request, Credentials credentials);
	
    /**
    * 
    * Method to determine if a CredentialsBinder supports a specific class or not.
    * 
    * @param clazz The class to determine is supported or not
    * @return true if this class is supported by the CredentialsBinder, false otherwise.
    */
    boolean supports(Class clazz);
}