Java Reference
In-Depth Information
WebTarget objects are immutable, in that methods for altering WebTarget s, such as path , return new instances of
WebTarget . This pattern is very similar to the Builder pattern, although there is no build() method call. WebTarget s
can also be configured by registering features or providers via a call to the target's register method, passing either
type of class.
client.register(Feature.class)
client.register(Provider.class)
An example of a basic provider class that implements MessageBodyWriter is as follows:
@Provider
public class MyProvider implements WriterInterceptor {
@Override
public void aroundWriteTo(WriterInterceptorContext ctx) throws IOException,
WebApplicationException {
String customMessage = "This is a custom message";
OutputStream os = ctx.getOutputStream();
ctx.proceed();
os.write(customMessage.getBytes());
}
}
WriterInterceptor wraps calls to MessageBodyWriter.writeTo() . that wrapping makes it easy to develop
a MessageBodyWriter solution by simply implementing the aroundWriteTo method.
Note
Now let's take a look at how this provider class is registered to a web service client. In the following client, the
MyProvider interceptor is applied to the client for testing.
public static void main(String[] args){
// Obtain an instance of the client
Client client = ClientBuilder.newClient();
client.register(MyProvider.class);
WebTarget webTarget = client.target(" http://localhost:8080/IntroToJavaEE7/rest/simplerest " );
Response res = webTarget.request("text/plain").get();
System.out.println(res.readEntity(String.class));
}
Obtaining a Response
The example at the beginning of this section demonstrated a simple client that returns an XML response. However,
it is possible to return different response types by passing different String s or MediaType fields to the client target
request method. Table 8-2 lists the different MediaType fields that can be used. All fields listed within the table that
contain a _TYPE suffix are of type MediaType , whereas the others are static String types.
 
 
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