Java Reference
In-Depth Information
A GET request returns the HTTP status code 200 for a successful request. The
@Pro-
duces
annotation identifies to the client the MIME type of the response. In this case I
want to return JSON or XML:
@Produces({MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML})
The annotation accepts an array of
MediaType
instances, which are used for content ne-
gotiation based on the
Accept
header in the incoming request.
If I want to specify the response header, JAX-RS provides a factory class called
Re-
sponse
using the builder design pattern. Here's the implementation of the
findById
method that uses it:
@GET @Path("{id}")
@Produces({MediaType.APPLICATION_JSON, MediaType.APPLICATION_XML})
public Response findById(@PathParam("id") long id) {
return Response.ok(dao.findById(id))
.build();
}
The
ok
method on the
Response
class sets the response status code to 200. It takes an
object as an argument, which is added to the response. The
@PathParam
annotation also
converts the input ID from a string to a
long
automatically.
Inserting a new instance is a bit more complicated, because the newly inserted instance
needs its own URI. Because in this case the generated URI will contain an ID generated by
the database, the resource method is tied to HTTP POST requests, which are neither safe
nor idempotent.
Implementation detail
The
create
method returns a URL that includes the primary key from the database table.
That detail is not something you want to expose to the client. Some unique identifier is re-
quired; here the ID is used for simplicity.
The new URI is added to the response as part of its
Location
header. The new URI is
generated using the
UriBuilder
class from JAX-RS, based on the incoming URI:
