Java Reference
In-Depth Information
List<Variant> vs =
Variant.mediatypes("application/xml", "application/json")
.languages("en", "fr").build();
This code snippet calls the
build
method of the
VariantListBuilder
class. The
VariantListBuilder
class is invoked when you call the
mediatypes
,
lan-
guages
, or
encodings
methods. The
build
method builds a series of resource rep-
resentations. The
Variant
list created by the
build
method has all possible combina-
tions of items specified in the
mediatypes
,
languages
, and
encodings
methods.
In this example, the size of the
vs
object as defined in this code snippet is 4, and the con-
tents are as follows:
[["application/xml","en"], ["application/json","en"],
["application/xml","fr"],["application/json","fr"]]
The
javax.ws.rs.core.Request.selectVariant
method accepts a list of
Variant
objects and chooses the
Variant
object that matches the HTTP request. This
method compares its list of
Variant
objects with the
Accept
,
Accept-Encoding
,
Accept-Language
, and
Accept-Charset
headers of the HTTP request.
The following code snippet shows how to use the
selectVariant
method to select the
most acceptable
Variant
from the values in the client request.
@GET
public Response get(@Context Request r) {
List<Variant> vs = ...;
Variant v = r.selectVariant(vs);
if (v == null) {
return Response.notAcceptable(vs).build();
} else {
Object rep = selectRepresentation(v);
return Response.ok(rep, v);
}
}
The
selectVariant
method returns the
Variant
object that matches the request, or
null if no matches are found. In this code snippet, if the method returns null, a
Response
object for a non-acceptable response is built. Otherwise, a
Response
object with an OK
