As some of you may have already noticed, we’ve recently released Jersey 2.6 (Reference Implementation of JAX-RS – Java API for RESTful Web Services). In this article I’d like to introduce some of the new features, important bug fixes and other noteworthy changes.
Although I am not a big fan of sending JSON in other places than in the message body as the entity, for example in query parameter in case of requests, it’s not a rare use-case and the way how it can be solved in JAX-RS 2.0 gives me a nice opportunity to illustrate usage of two new interfaces, ParamConverterProvider and ParamConverter. You can then re-use this approach to inject other media-types or formats your application relies on via @*Param annotations (@MatrixParam, @QueryParam, @PathParam, @CookieParam, @HeaderParam).
Few times I’ve ran into a situation in which I wanted to return only a part of entity I was working with, in my service, to the client-side. Feature that would allow me to send this partial set of fields should not only be driven by my own filtering rules but it also should take into consideration application roles the current user is in. It’s not an uncommon use-case I’d say so in Jersey we’d come up with the Entity Filtering concept that would allow you to do such a thing: sending subgraph of entities from server to client (and vice versa), define your own filtering rules and make sure users get only the fields they are supposed to see.
Since JAX-RS 2.0 you can use Bean Validation to validate inputs received from users and outputs created in your application. It’s a handy feature and in most cases it works great. But what if you’re using also MVC and you want to display custom error page if something goes wrong? Or what if you want to handle Bean Validation issues in a slightly different way than JAX-RS implementation you’re using does? This article will give you some answers to these questions.
Common use-case in web-application development is aggregating data from multiple resources, combining them together and returning them to the used as XML/JSON or as a web page. In Java world these (external) resources can be approached via standardized Clients from JAX-RS 2.0. Jersey 2 application can use so-called managed client mechanism that brings a convenient way to create JAX-RS clients and web targets for such resources.
When you register providers (such as filters and interceptors) in your application they’re associated and applied to each resource method by default. In other words they’re bound globally. For most cases this approach is sufficient but sometimes, especially when you want to use your provider only with a few methods, it’s not enough. JAX-RS 2.0 brings a solution for this situation: Name and Dynamic Binding.
There has been some confusion on StackOverflow lately about how to register JAX-RS resource classes and custom providers in Jersey 2. The main problem seemed to be finding and using correct properties and methods to configure a JAX-RS/Jersey application. In this article I’d like to discuss 3 ways how to configure such an application properly.