Application context path at JAX-RS 2.0 resource instance construction

问题

Is it possible to get the context path for a Java EE 7 application at JAX-RS 2.0 resource class instance construction time (and possibly at static class initialization time, too), or is it only available during requests to endpoints in the resource class?

By context path I mean the String that would be returned by a call to a HttpServletRequest#getContextPath() within the Java EE 7 application.

I imagine that you probably could have multiple context path aliases for a deployed application. If so, context path might be available only at request time.

I don't care, however, about the context path that was actually used in the URL for the request. A canonical or default context path that will work for the endpoints in the class is good enough for me.

The technique to obtain such a context path need not be JAX-RS 2.0 specific. It could come from some other Java EE 7 spec, as long as it works at JAX-RS 2.0 resource class construction time (or, more broadly, at static class initialization time).

Update:

I forgot to mention that the class is CDI @ApplicationScoped, so its constructor is not called at request time, as it would be if it were @RequestScoped.

回答1:

You can get the base URI for your REST application by injecting UriInfo in a resource's constructor:

@ApplicationScoped
@Path("/resourcePath")
public class MyRestResource {

    public MyRestResource (@Context UriInfo uriInfo) {
        URI uri = uriInfo.getBaseUri();
    }

    @GET
    public Response someMethod(){
        ...
    }
}

Most of the UriInfo methods will return IllegalStateException at resource construction time, but the getBaseUri() method will work.

It will return an URI like http://<hostname>:<port>/<context-path>/<base-path>.

But i'm not sure it would be possible to get it statically at class initialization time...

来源：https://stackoverflow.com/questions/26257028/application-context-path-at-jax-rs-2-0-resource-instance-construction