Validate JAX-RS query parameters

 

It’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 (HttpServletRequest using @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());
	}
	}
	}

view raw

JAXRSReqFilter.java

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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 {
	}

view raw

QueryParamValidator.java

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	@Path("test")
	public class TestResource {
	@GET
	@QueryParamValidator
	public String test(@QueryParam("p") String p){
	return "Param "+ p + " on " + new Date();
	}
	}

view raw

TestResource.java

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Further reading

• My eBook: REST assured with JAX-RS
• JAX-RS 2.0 article in the Java Magazine

Cheers!

 

 

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