10.16.2. Dynamic Proxy

You can create an instance of a client proxy using one of getPort methods on the Service. 
/** 
 * The getPort method returns a proxy. A service client
 * uses this proxy to invoke operations on the target
 * service endpoint. The <code>serviceEndpointInterface</code>
 * specifies the service endpoint interface that is supported by
 * the created dynamic proxy instance.
 */
public <T> T getPort(QName portName, Class<T> serviceEndpointInterface)
{
...
}
  
/** 
 * The getPort method returns a proxy. The parameter
 * <code>serviceEndpointInterface</code> specifies the service
 * endpoint interface that is supported by the returned proxy.
 * In the implementation of this method, the JAX-WS
 * runtime system takes the responsibility of selecting a protocol
 * binding (and a port) and configuring the proxy accordingly.
 * The returned proxy should not be reconfigured by the client.
 *
 */
public <T> T getPort(Class<T> serviceEndpointInterface)
{
...
}
The Service Endpoint Interface (SEI) is usually generated using tools. For details see Top Down (Using wsconsume).
A generated static Service usually also offers typed methods to get ports. These methods also return dynamic proxies that implement the SEI. 
@WebServiceClient(name = "TestEndpointService", targetNamespace = "http://org.jboss.ws/wsref", 
  wsdlLocation = "http://localhost.localdomain:8080/jaxws-samples-webserviceref?wsdl")
public class TestEndpointService extends Service
{
   ...
   
   public TestEndpointService(URL wsdlLocation, QName serviceName) {
      super(wsdlLocation, serviceName);
   }
   
   @WebEndpoint(name = "TestEndpointPort")
   public TestEndpoint getTestEndpointPort() 
   {
      return (TestEndpoint)super.getPort(TESTENDPOINTPORT, TestEndpoint.class);
   }
}