@HeaderParam

The @javax.ws.rs.HeaderParam annotation is used to inject HTTP request header values. For example, what if your application was interested in the web page that referred to or linked to your web service? You could access the HTTP Referer header using the @HeaderParam annotation:

@Path("/myservice")
public class MyService {

   @GET
   @Produces("text/html")
   public String get(@HeaderParam("Referer") String referer) {
     ...
   }
}

The @HeaderParam annotation is pulling the Referer header directly from the HTTP request and injecting it into the referer method parameter.

Raw Headers

Sometimes you need programmatic access to view all headers within the incoming request. For instance, you may want to log them. The JAX-RS specification provides the javax.ws.rs.core.HttpHeaders interface for such scenarios.

public interface HttpHeaders {
   public List<String> getRequestHeader(String name);
   public MultivaluedMap<String, String> getRequestHeaders();
...
}

The getRequestHeader() method allows you to get access to one particular header, and getRequestHeaders() gives you a map that represents all headers.

As with UriInfo, you can use the @Context annotation to obtain an instance of HttpHeaders. Here’s an example:

@Path("/myservice")
public class MyService {

   @GET
   @Produces("text/html")
   public String get(@Context HttpHeaders headers) {
      String referer = headers.getRequestHeader("Referer").get(0);
      for (String header : headers.getRequestHeaders().keySet())
      {
         System.out.println("This header was set: " + header);
      }
     ...
   }
}