Package javax.ws.rs.client
package javax.ws.rs.client
The JAX-RS client API
The JAX-RS client API is a Java based API used to access Web resources. It is not restricted to resources implemented using JAX-RS. It provides a higher-level abstraction compared to aplain HTTP communication API
as well as integration with the JAX-RS extension
providers, in order to enable concise and efficient implementation of
reusable client-side solutions that leverage existing and well
established client-side implementations of HTTP-based communication.
The JAX-RS Client API encapsulates the Uniform Interface Constraint –
a key constraint of the REST architectural style – and associated data
elements as client-side Java artifacts and supports a pluggable architecture
by defining multiple extension points.
Client API Bootstrapping and Configuration
The main entry point to the API is aClientBuilder
that is used to bootstrap Client
instances -
configurable
, heavy-weight objects
that manage the underlying communication infrastructure and serve as the root
objects for accessing any Web resource. The following example illustrates the
bootstrapping and configuration of a Client
instance:
Client client = ClientBuilder.newClient(); client.property("MyProperty", "MyValue") .register(MyProvider.class) .enable(MyFeature.class);
Accessing Web Resources
A Web resource can be accessed using a fluent API in which method invocations are chained to configure and ultimately submit an HTTP request. The following example gets atext/plain
representation of the resource identified by
"http://example.org/hello"
:
Client client = ClientBuilder.newClient(); Response res = client.target("http://example.org/hello").request("text/plain").get();Conceptually, the steps required to submit a request are the following:
- obtain an
Client
instance - create a
WebTarget
pointing at a Web resource build
a request- submit a request to directly retrieve a response or get a prepared
Invocation
for later submission
WebTarget
instance is bound to a
concrete URI, e.g. "http://example.org/messages/123"
,
or a URI template, e.g. "http://example.org/messages/{id}"
.
That way a single target can either point at a particular resource or represent
a larger group of resources (that e.g. share a common configuration) from which
concrete resources can be later derived:
// Parent target for all messages WebTarget messages = client.target("http://example.org/messages/{id}"); WebTarget msg123 = messages.resolveTemplate("id", 123); // New target for http://example.org/messages/123 WebTarget msg456 = messages.resolveTemplate("id", 456); // New target for http://example.org/messages/456
Generic Invocations
AnInvocation
is a request that has been prepared
and is ready for execution.
Invocations provide a generic interface that enables a separation of concerns
between the creator and the submitter. In particular, the submitter does not
need to know how the invocation was prepared, but only whether it should be
executed synchronously or asynchronously.
Invocation inv1 = client.target("http://example.org/atm/balance") .queryParam("card", "111122223333").queryParam("pin", "9876") .request("text/plain").buildGet(); Invocation inv2 = client.target("http://example.org/atm/withdrawal") .queryParam("card", "111122223333").queryParam("pin", "9876") .request().buildPost(text("50.0"))); Collectioninvs = Arrays.asList(inv1, inv2); // Executed by the submitter Collection ress = Collections.transform(invs, new F<Invocation, Response>() { public Response apply(Invocation inv) {return inv.invoke(); } });
-
ClassDescriptionUniform interface for asynchronous invocation of HTTP methods.Client is the main entry point to the fluent API used to build and execute client requests in order to consume responses returned.Main entry point to the client API used to bootstrap
Client
instances.Client request filter context.An extension interface implemented by client request filters.Client response filter context.An extension interface implemented by client response filters.Entity<T>Encapsulates message entity including the associated variant information.A client request invocation.A client request invocation builder.InvocationCallback<RESPONSE>Callback that can be implemented to receive the asynchronous processing events from the invocation processing.JAX-RS client-side runtime processing exception thrown to indicate that response processing has failed (e.g.Uniform interface for synchronous invocation of HTTP methods.A resource target identified by the resource URI.