Configuring custom PropertyEditors

In the previous example, we learned how to configure converters for an HTTP request and response data. There are other kinds of conversions that take place, especially in regards to dynamically converting parameters to various objects, such as Strings to Date or an Integer.

When we declare a mapping method in a controller, Spring allows us to freely define the method signature with the exact object types that we require. The way in which this is achieved is via the use of the PropertyEditor implementations. PropertyEditor is a default concept defined as part of the JDK and designed to allow the transformation of a textual value to a given type. It was initially intended to be used to build Java Swing / Abstract Window Toolkit (AWT) GUI and later proved to be a good fit for Spring's need to convert web parameters to method argument types.

Spring MVC already provides you with a lot of PropertyEditor implementations for most of the common types, such as Boolean, Currency, and Class. Let's say that we want to create a proper Isbn class object and use this in our controller instead of a plain String.