Expert Spring MVC and Web Flow

public void setSearchBy(String searchBy) {

this.searchBy = searchBy;

}

}

}

Let’s chat a bit about this example, which highlights the strengths and weaknesses of this

Controllertype. A strength of this Controlleris that its superclass AbstractControllerpro-

vides helpful facilities such as enforcing allowed HTTP methods (as done in the constructor

in Listing 6-59). A shortcoming of this ability is that the allowed HTTP methods are common

across all request handlers inside the class, as there is no way to declaratively configure the

list of allowed request methods on a per–request handling basis. In this example, where all

requests are read-only, globally restricting to GET makes sense. If your MultiActionController

can handle different request methods at different times, you will have to declare those allowed

HTTP methods inside each handler method. For instance, the code from Listing 6-60 can be

used.

Listing 6-60.Ensure HTTP Methods

private void ensureMethod(HttpServletRequest request, String ... methods)

throws RequestMethodNotSupportedException {

for (String method : methods) {

if (request.getMethod().equals(method)) {

return;

}

}

throw new RequestMethodNotSupportedException("The request method " +

request.getMethod() + " is not allowed");

}

You can use such a method at the beginning of each request handling method (as shown

in Listing 6-61), but be sure to propagate the RequestMethodNotSupportedExceptionas the

superclass knows how to deal with it.

Listing 6-61.Example of Ensuring HTTP Method for a Request Handling Method

public ModelAndView findByUsername(HttpServletRequest request,

HttpServletResponse response, SearchCriteria criteria)

throws RequestMethodNotSupportedException {

ensureMethod(request, METHOD_GET);

Account account = accountService.findAccountByUsername(

criteria.getSearchBy());

return new ModelAndView("viewAccount", "account", account);

}

174 CHAPTER 6 ■THE CONTROLLER MENAGERIE