Posts

Showing posts from August, 2017

Dynamically adding an interceptor to a build-in CDI bean

In Java EE's CDI, beans can be augmented via 2 artefacts; Decorators and Interceptors. Decorators are typically owned by the application code and can decorate a bean that's shipped by the container (build-in beans) or a library. Interceptors are typically shipped by a library and can be applied (bound) to a bean that's owned by the application. So how do you bind a library shipped interceptor to a library shipped/build-in bean? In CDI 1.2 and before this wasn't really possible, but in CDI 2.0 we can take advantage of the new InterceptionFactory to do just this. It's not entirely trivial yet, but it's doable. In this article we'll demonstrate how to apply the @RememberMe interceptor binding from the new Java EE 8 Security spec to a build-in bean of type HttpAuthenticationMechanism, which is from the Security spec as well. First we configure our authentication mechanism by means of the following annotation: @BasicAuthenticationMechanismDefinition( …

Extensionless URLs with JSF 2.3

An extensionless URL is a URL without a final suffix like .xhtml, .html, .jsp, etc. Such a suffix is seen as technical "clutter" that's hard to remember for humans. Servers often need it though to route a request to the right controller. JSF, a Java EE MVC framework, has supported extensionless URLs for some time via PrettyFaces (now merged to the general Rewrite framework) and OmniFaces. Both of these solutions used various workarounds to trick JSF into working with extensionless URLs. Though JSF 2.3 does, unfortunately, still not support extensionless URLs fully out of the box via e.g. a single parameter, it can provide support for it by basically combining the new support for exact mapping and the API for obtaining a list of all view resources. Additionally combining this with the Servlet 3.1 feature for dynamically adding Servlet mappings and some JDK8 streaming and lambdas, makes it possible to enable extensionless support with just 2 statements (albeit somewhat…

Dynamic beans in CDI 2.0

A while ago we wrote about CDIs ability to dynamically add Bean<T> instances to the CDI runtime. A Bean<T> is a kind of factory for beans, that makes types available for injection, lookup via the bean manager, or by referencing them in expression language. CDI producers (via the @Produces annotation) fulfil a somewhat similar role, but they essentially only make the "create instance" method dynamic; the rest (like scope, types, etc) is more or less static. A programmatically added Bean<T> essentially makes all those aspects dynamic. As the previous article showed, dynamically adding such Bean<T> is a bit more work and it's quite verbose, as well as a little complex as the developer has to find out what to return as a default for various methods that are not directly of interest. CDI 2.0 has addressed some of the above issues by providing a very convenient builder that not only makes creating a Bean<T> instance far less verbose, but als…