Advising controllers with the @ControllerAdvice annotation

The @ControllerAdvice annotation is a component annotation allowing implementation classes to be auto-detected through

classpath scanning. It is automatically enabled when using the MVC namespace or the MVC Java config.

Classes annotated with @ControllerAdvice can contain @ExceptionHandler, @InitBinder, and @ModelAttribute annotated

methods, and these methods will apply to @RequestMapping methods across all controller hierarchies as opposed to the controller

hierarchy within which they are declared.

The @ControllerAdvice annotation can also target a subset of controllers with its attributes:

// Target all Controllers annotated with @RestController
@ControllerAdvice(annotations = RestController.class)
public class AnnotationAdvice {}

// Target all Controllers within specific packages
@ControllerAdvice("org.example.controllers")
public class BasePackageAdvice {}

// Target all Controllers assignable to specific classes
@ControllerAdvice(assignableTypes = {ControllerInterface.class, AbstractController.class})
public class AssignableTypesAdvice {}

Customizing data binding with @InitBinder

Annotating controller methods with @InitBinder allows you to configure web data binding directly within your controller class. @InitBinder

identifies methods that initialize the WebDataBinder that will be used to populate command and form object arguments of annotated handler

methods.

Such init-binder methods support all arguments that @RequestMapping supports, except for command/form objects and corresponding

validation result objects. Init-binder methods must not have a return value. Thus, they are usually declared as void. Typical arguments include

WebDataBinder in combination with WebRequest orjava.util.Locale, allowing code to register context-specific editors.

The following example demonstrates the use of @InitBinder to configure a CustomDateEditor for all java.util.Date form properties.

    @InitBinder
    public void initBinder(WebDataBinder binder) {
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        dateFormat.setLenient(false);
        binder.registerCustomEditor(Date.class, new CustomDateEditor(dateFormat, false));
    }

Advising controllers with the @ControllerAdvice annotation