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 Sping Spring Web MVC FormControllers, the forms play the role of "commands" in the more general CommandController model. LoginController defaults this Command class: | Code Block |
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| title | LoginController afterPropertiesSet() excerpt |
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public void afterPropertiesSet() throws Exception {
if (this.getCommandClass() == null) {
this.setCommandName("credentials");
this.setCommandClass(UsernamePasswordCredentials.class);
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In BaseCommandController, we have: | Code Block |
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| title | BaseCommandController getCommand() |
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/**
* 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();
}
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And the createCommand() method to which it delegates: | Code Block |
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| title | BaseCommandController createCommand() |
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/**
* 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();
}
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