JAX-RS :Validate Query Parameter Passed in by the Caller

t’s easy to validate parameters in JAX-RS using filters – ContainerRequestFilter to be specific. There are other options at your disposal, e.g. using (CDI or EJB) interceptors, or injecting (HttpServletRequestusing @Context)

Scenario: Validate Query Parameter Passed in by the Caller

Steps

• Implement filter
• Extracts query parameter from ContainerRequestContext
• Performs the validation – aborts the request with an appropriate response status (and the error message)

@Provider

@QueryParamValidator

public class JAXRSReqFilter implements ContainerRequestFilter {

    @Override

    public void filter(ContainerRequestContext requestContext) throws IOException {

        MultivaluedMap < String, String > queryParameters = requestContext.getUriInfo().getQueryParameters();

        String queryParam = queryParameters.keySet().stream().findFirst().get();

        System.out.println("Query param - " + queryParam);

        if (!queryParam.equals("p")) {

            requestContext.abortWith(Response

                .status(Response.Status.BAD_REQUEST)

                .entity("Invalid Query Param " + queryParam)

                .build());

        }

    }

}

Enforce Filter

• Use @NameBinding to decorate custom annotation
• Use the custom annotation on the JAX-RS method

@NameBinding

@Retention(RetentionPolicy.RUNTIME)

@Target({ElementType.TYPE, ElementType.METHOD})

public @interface QueryParamValidator {

}

@Path("test")

public class TestResource {

    @GET

    @QueryParamValidator

    public String test(@QueryParam("p") String p){

        return "Param "+ p + " on " + new Date();

    }

}