Previous sections have presented examples of annotated types, mostly annotated method parameters but also annotated fields of a class, for the injection of values onto those types.
This section presents the rules of injection of values on annotated types. Injection can be performed on fields, constructor parameters, resource/sub-resource/sub-resource locator method parameters and bean setter methods. The following presents an example of all such injection cases:
@Path("id: \d+") public class InjectedResource { // Injection onto field @DefaultValue("q") @QueryParam("p") private String p; // Injection onto constructor parameter public InjectedResource(@PathParam("id") int id) { ... } // Injection onto resource method parameter @GET public String get(@Context UriInfo ui) { ... } // Injection onto sub-resource resource method parameter @Path("sub-id") @GET public String get(@PathParam("sub-id") String id) { ... } // Injection onto sub-resource locator method parameter @Path("sub-id") public SubResource getSubResource(@PathParam("sub-id") String id) { ... } // Injection using bean setter method @HeaderParam("X-header") public void setHeader(String header) { ... } }
There are some restrictions when injecting on to resource classes with a life-cycle other than per-request. In such cases it is not possible to injected onto fields for the annotations associated with extraction of request parameters. However, it is possible to use the @Context annotation on fields, in such cases a thread local proxy will be injected.
The @FormParam annotation is special and may only be utilized on resource and sub-resource methods. This is because it extracts information from a request entity.