在Dropwizard资源方法中出现错误

Question

I am trying to study Dropwizard and so, I am trying to build a simple calculator.

This is the relevant code I wrote:

In the application class:

@Override
public void run(final CalDropWizServerDemoConfiguration configuration,
                final Environment environment) {

    final CalDropWizServerDemoResource resource = new CalDropWizServerDemoResource();

    environment.jersey().register(resource);

    final TemplateHealthCheck healthCheck = new TemplateHealthCheck();
    environment.healthChecks().register("Sum", healthCheck);
}

The resource class:

@Path("/calculator")
@Produces(MediaType.APPLICATION_JSON)
public class CalDropWizServerDemoResource {

    private final AtomicLong counter;

    public CalDropWizServerDemoResource(){

        this.counter = new AtomicLong();
    }

    @GET
    @Timed
    @Path("/sum")
    public Sum calcSum(@PathParam("a") int a, @PathParam("b") int b) {

        System.out.println(a);
        System.out.println(b);

        return new Sum(counter.incrementAndGet(), a + b);
    }
}

The api (POJO of the json response) class:

public class Sum {

    private long id;
    private int sum;

    public Sum() {
        // Jackson deserialization
    }

    public Sum(long id, int sum) {

        this.id = id;
        this.sum = sum;
    }

    @JsonProperty
    public long getId() {
        return id;
    }

    @JsonProperty
    public int getSum() {
        return sum;
    }
}

I don't use a configuration yaml so the configuration class is the default one.

My problem is that when I call, for example:

http://localhost:8080/calculator/sum?a=1&b=5

I get 0 as the sum. I debugged and found out that the values of a and b in the calcSum() method are accepted as 0. Why is that?

Thanks!!

Answer 1

If you are using @PathParams to input a and b , you need to have placeholders for them in your @Path url. It can be like this:

@Path("/sum/{a}/{b}")

The label given to each placeholder in @Path should match the value passed to corresponding @PathParam declaration.

Answer 2

Replace @PathParam with @QueryParam and it should work fine.

@GET
@Timed
@Path("/sum")
public Sum calcSum(@QueryParam("a") int a, @QueryParam("b") int b) {
    System.out.println(a);
    System.out.println(b);

    return new Sum(counter.incrementAndGet(), a + b);
}