Spring @MVC and @RequestParam validation

Question

I would like to use the @RequestParam annotation like so:

@RequestMapping
public void handleRequest( @RequestParam("page") int page ) {
   ...
}

However, I want to show page 1 if the user fiddles with the URL parameters and tries to go to page "abz" or something non-numerical. Right now, the best I can get Spring to do is return a 500. Is there a way to override this behavior cleanly without having to take in the parameter as a String?

I looked at the @ExceptionHandler annotation, but it doesn't seem to do anything when I set I use @ExceptionHandler(TypeMismatchException.class) . Not sure why not.

Suggestions?

PS Bonus question: Spring MVC is called Spring MVC. Is Spring MVC with annotations just called Spring @MVC? Google treats them as the same name, which is annoying.

Answer 1

The ConversionService is a nice solution, but it lacks a value if you give an empty string to your request like ?page= The ConversionService is simply not called at all, but page is set to null (in case of Integer ) or an Exception is thrown (in case of an int )

This is my preferred solution:

@RequestMapping
public void handleRequest( HttpServletRequest request ) {
    int page = ServletRequestUtils.getIntParameter(request, "page", 1);
}

This way you always have a valid int parameter.

Answer 2

Since Spring 3.0, you can set a ConversionService . @InitBinder 's value specifies a particular parameter to apply that service to:

@InitBinder("page")
public void initBinder(WebDataBinder binder) {
    FormattingConversionService s = new FormattingConversionService();
    s.addFormatterForFieldType(Integer.class, new Formatter<Integer>() {
        public String print(Integer value, Locale locale) {
            return value.toString();
        }

        public Integer parse(String value, Locale locale)
                throws ParseException {
            try {
                return Integer.valueOf(value);
            } catch (NumberFormatException ex) {
                return 1;
            }
        }
    });
    binder.setConversionService(s);
}