Java RESTful Web Services (JAX-RS)

Remarks#

Unlike SOAP and the WS- stack, which are specified as W3C standards, REST is really a set of principles for designing and using web-based interface. REST / RESTful applications rely heavily on other standards:

HTTP
URI, URL
XML, JSON, HTML, GIF, JPEG, and so forth (resource representations)

The role of JAX-RS (Java API for RESTful Web Services) is to provide APIs that support building RESTful services. However, JAX-RS is just one way of doing this. RESTful services can be implemented other ways in Java, and (indeed) in many other programming languages.

Simple Resource

First of all for a JAX-RS application must be set a base URI from which all the resources will be available. For that purpose the javax.ws.rs.core.Application class must be extended and annotated with the javax.ws.rs.ApplicationPath annotation. The annotation accepts a string argument which defines the base URI.

@ApplicationPath(JaxRsActivator.ROOT_PATH)
public class JaxRsActivator extends Application {

    /**
     * JAX-RS root path.
     */
    public static final String ROOT_PATH = "/api";

}

Resources are simple POJO classes which are annotated with the @Path annotation.

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;

@Path("/hello")
public class HelloWorldResource {
    public static final String MESSAGE = "Hello StackOverflow!";

    @GET
    @Produces("text/plain")
    public String getHello() {
        return MESSAGE;
    }
}

When a HTTP GET request is sent to /hello, the resource responds with a Hello StackOverflow! message.

GET method types

DELETE method

POST Method

Exception Mapper

UriInfo

SubResources

Custom parameter converters

Name binding