My JSF Books/Videos My JSF Tutorials OmniFaces/JSF PPTs
JSF 2.3 Tutorial
JSF Caching Tutorial
JSF Navigation Tutorial
JSF Scopes Tutorial
JSF Page Author Beginner's Guide
OmniFaces 2.3 Tutorial Examples
OmniFaces 2.2 Tutorial Examples
JSF Events Tutorial
OmniFaces Callbacks Usages
JSF State Tutorial
JSF and Design Patterns
JSF 2.3 New Features (2.3-m04)
Introduction to OmniFaces
25+ Reasons to use OmniFaces in JSF
OmniFaces Validators
OmniFaces Converters
JSF Design Patterns
Mastering OmniFaces
Reusable and less-verbose JSF code

My JSF Resources ...

Java EE Guardian
Member of JCG Program
Member MVB DZone
Blog curated on ZEEF
OmniFaces is an utility library for JSF, including PrimeFaces, RichFaces, ICEfaces ...

[OmniFaces Utilities] - Find the right JSF OmniFaces 2 utilities methods/functions

Search on blog

Petition by Java EE Guardians

Twitter

duminică, 22 noiembrie 2015

JSF 2.3 Take advantage of the new generic parameters in Converter<T> and Validator<T>

As you probably know, in JSF 2.2 we can write a custom converter by extending the Converter interface, and a custom validator by extending the Validator interface. The methods defined in these interfaces works with Object class, as you can see in the below skeletons:

JSF 2.2 custom converter skeleton

@FacesConverter(value = "fooConverter")
public class FooConverter implements Converter {

 @Override
 public Object getAsObject(FacesContext context, UIComponent component, String value) {
  ...
 }

 @Override
 public String getAsString(FacesContext context, UIComponent component, Object value) {
  // check value type and cast it
  ...
 }
}

JSF 2.2 custom validator skeleton

@FacesValidator(value = "fooValidator")
public class FooValidator implements Validator {

 @Override
 public void validate(FacesContext fc, UIComponent uic, Object o) throws ValidatorException {
  // check value type and cast it
  ...
 }
}

Starting with JSF 2.3 Converter and Validator have now been parameterized and implementations can concisely define the exact input type.

// Mojarra 2.3.0-m04 Converter snippet of source code
public interface Converter<T> {
 T getAsObject(FacesContext context, UIComponent component, String value);
 String getAsString(FacesContext context, UIComponent component, T value);
}

// Mojarra 2.3.0-m04 Validator snippet of source code
public interface Validator<T> {
 void validate(FacesContext context, UIComponent component, T value);
}

For example, let's suppose that we have the following simple class:

public class User implements Serializable {

 private String name;
 private String email;

 public User(String name, String email) {
  this.name = name;
  this.email = email;       
 }

 // getters and setters  
 // equal and hash code
 ...
}

Now, we can convert/validate a string against this class by indicating the User type in our custom converter/validator:

JSF 2.3 custom converter with defined type example

@FacesConverter(value = "UserConverter")
public class UserConverter implements Converter<User> {

 @Override
 public User getAsObject(FacesContext context, UIComponent component, String value) {
  ...
 }

 @Override
 public String getAsString(FacesContext context, UIComponent component, User value) {
  // no need to check value type and cast it
  ...
 }
}

JSF 2.3 custom validator with defined type example

@FacesValidator(value = "UserValidator")
public class UserValidator implements Validator<User> {

 @Override
 public void validate(FacesContext fc, UIComponent uic, User o) throws ValidatorException {
  // no need to check value type and cast it
  ...
 }
}

Note In JSF 2.3, you can still write custom converters/validators  as in JSF 2.2. If you don't want to take advantage of the new generic parameters, you can use the classical approach.

A complete and functional example can be found here. I've tested under Payara 4.1.

Niciun comentariu :

Trimiteți un comentariu

JSF BOOKS COLLECTION

Postări populare

OmniFaces/JSF Fans

Follow by Email

Visitors Starting 4 September 2015

Locations of Site Visitors