带有GenericType的RESTful Web服务

Question

here is the first part of my code :

@Path("compute/{x}")
@GET
@Produces(MediaType.TEXT_PLAIN) // "text/plain"
public List<Double> compute(@PathParam("x") Double x) {
    List<Double> list = new Vector<Double>();
    list.add(Math.log(x));
    list.add(Math.exp(x));
    return list;
}

I am learning/building a RESTful web service. The client exploiting that RESTful web service is doing like this.

javax.ws.rs.client.Client client = ClientBuilder.newClient();

WebTarget uri_basique = client
        .target("http://localhost:8080/Rest_ws/rest");

WebTarget targeted_resource = uri_basique.path("simple/compute/{x}")
        .resolveTemplate("x", 5);

Builder builder = targeted_resource.request(MediaType.TEXT_PLAIN);
List<Double> compute = builder.get(new GenericType<List<Double>>(){});

System.out.println("log (5) = " + compute.get(0));
System.out.println("exp (5) = " + compute.get(1));

It is supposed to work. But when I execute I get:

javax.ws.rs.InternalServerErrorException: HTTP 500 Internal Server Error
    ...
    at ws_rs.Client.test3(Client.java:26)

The problematic line is the line :

List<Double> compute = builder.get(new GenericType<List<Double>>(){});

If someone can provide any explanation/solution to me.

Answer 1

HTTP 500 Internal Server Error means that there is some error while calling the rest api. It seems that the web service is not able to translate list as "text/plain" and hence it is throwing error. Jersey does not provide MessageBodyReader/Writer to translate java.util.List into "text/plain". You have to provide a custom MessageBodyReader/Writer for this.