JAX-RS - Injecting HttpHeaders with @Context annotation

An instance of HttpHeaders can be injected as field or method parameter using the @Context annotation. HttpHeaders provides access to HTTP request header information.

Example

A JAX-RS resource injecting HttpHeaders

@Path("/users")
public class UserResource {
    @Context
    private HttpHeaders httpHeaders;

    @GET
    public String getUsers() {
        System.out.println("In getUsers() method");
        printHeaderInfo();
        return "returning dummy user list";
    }

    private void printHeaderInfo() {
        System.out.println("---------------");
        MultivaluedMap<String, String> requestHeaders = httpHeaders.getRequestHeaders();
        for (Map.Entry<String, List<String>> entry : requestHeaders.entrySet()) {
            System.out.println(entry.getKey() + "=" + entry.getValue());
        }
    }
}

The client

public class UserClient {
    public static void main(String[] args) throws Exception {
        Client client = ClientBuilder.newBuilder().build();
        WebTarget target =
                client.target("http://localhost:8080/users");

        String response = target.request()
                                .header("aCustomHeader", "aValue")
                                .get(String.class);
        System.out.println("response: " + response);
    }
}

Output

response: returning dummy user list

Output on server console

In getUsers() method
---------------
acustomheader=[aValue]
user-agent=[Jersey/2.25.1 (HttpUrlConnection 1.8.0_111)]
host=[localhost:8080]
accept=[text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2]
connection=[keep-alive]

Example Project

Dependencies and Technologies Used:

• jersey-server 2.25.1: Jersey core server implementation.
• jersey-container-servlet 2.25.1: Jersey core Servlet 3.x implementation.
• JDK 1.8
• Maven 3.3.9