Overview of a Jersey-Annotated Application

The following code sample is a very simple example of a root resource class using JAX-RS annotations. The sample shown here is from the samples that ship with Jersey, and which can be found in the following directory of that installation: jersey/samples/helloworld/src/main/java/com/sun/jersey/samples/helloworld/resources/HelloWorldResource.java.

package com.sun.jersey.samples.helloworld.resources;

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

// The Java class will be hosted at the URI path "/helloworld"
@Path("/helloworld")
public class HelloWorldResource {
    
    // The Java method will process HTTP GET requests
    @GET
    // The Java method will produce content identified by the MIME Media
    // type "text/plain"
    @Produces("text/plain")
    public String getClichedMessage() {
        // Return some cliched textual content
        return "Hello World";
    }
}

The following annotations are used in this example:

• The @Path annotation's value is a relative URI path. In the example above, the Java class will be hosted at the URI path /helloworld. This is an extremely simple use of the @Path annotation. What makes JAX-RS so useful is that you can embed variables in the URIs. URI path templates are URIs with variables embedded within the URI syntax.

• The @GET annotation is a request method designator, along with@POST, @PUT, @DELETE, and @HEAD, that is defined by JAX-RS, and which correspond to the similarly named HTTP methods. In the example above, the annotated Java method will process HTTP GET requests. The behavior of a resource is determined by the HTTP method to which the resource is responding.

• The @Produces annotation is used to specify the MIME media types of representations a resource can produce and send back to the client. In this example, the Java method will produce representations identified by the MIME media type "text/plain".

• The @Consumes annotation is used to specify the MIME media types of representations a resource can consume that were sent by the client. The above example could be modified to set the cliched message as shown here:

  @POST
  @Consumes("text/plain")
  public void postClichedMessage(String message) {
      // Store the message
  }