Head First Servlets and JSP, 2nd Edition

Bean tags convert primitive properties automatically

If you’re familiar with JavaBeans from any earlier lifetime, this is no surprise to you. JavaBean properties can be anything, but if they’re Strings or primitives, all the coercing is done for you.

That’s right—you don’t have to do the parsing and conversion yourself

If we make the type Employee (instead of Person)

It all works

The <jsp:setProperty> action takes the String request parameter, converts it to an int, and passes that int to the bean’s setter method for that property.

There are no Dumb Questions

Q:

Q: OK, I’m thinking that the Container code is doing some kind of Integer.parseInt(“343”), so wouldn’t you get a NumberFormatException if the user doesn’t type in something that can be parsed to an int? Like, what if the user types “three” in the employee ID field?

A:

A: Good catch. Yes, something will definitely go wrong if the request parameter for the empID property can’t be parsed into an int. You need to validate the contents of that field, to make sure it contains only numeric characters. You could send the form data to a servlet first, instead of sending it straight to the JSP. But if you’re committed to going from the form straight to the JSP, and you don’t want scripting, just use JavaScript in the HTML form to check the field ...