🔗 Enable JSON conversion in MOXy to avoid 415 Unsupported Media Type

If you follow the “Getting Started” tutorial for Jersey (an API for writing REST apps in Java), you’ll get a nice working “Hello World” example called “simple-service”. However, if you try to extend it to use JSON using MOXy’s advertised auto-coversion of JSON into Java objects, you’ll get a “415 Unsupported Media Type” HTTP response if you don’t do it right.

Things that can cause 415 Unsupported Media Type:

Not having MOXy enabled in your pom.xml

Make sure this is present and uncommented in your pom.xml file:

      <dependency>
         <groupId>org.glassfish.jersey.media</groupId>
         <artifactId>jersey-media-moxy</artifactId>
      </dependency>

Not using @Consumes and @Produces annotations

Make sure they are set in your method:

   @POST
   @Consumes("application/json")
   @Produces("application/json")
   public string postIt(MyObject obj) {

Not sending Content-Type headers

Here’s an incantation of curl that does the right thing for testing a POST:

curl -v -H "Content-Type: application/json" -X POST -d '{"name":"hisham"}' http://localhost:8080/myapp/myresource

Not initalizing the JSON feature in MOXy

This is the default initalization given in the “simple-service” minimal example:

   public static HttpServer startServer() {
      // create a resource config that scans for JAX-RS resources and providers
      // in com.example package
      final ResourceConfig rc = new ResourceConfig().packages("com.example");

      // create and start a new instance of grizzly http server
      // exposing the Jersey application at BASE_URI
      return GrizzlyHttpServerFactory.createHttpServer(URI.create(BASE_URI), rc);
   }

and this is how you should extend it:

   public static HttpServer startServer() {

      final MoxyJsonConfig moxyJsonConfig = new MoxyJsonConfig();
      final ContextResolver jsonConfigResolver = moxyJsonConfig.resolver();

      // create a resource config that scans for JAX-RS resources and providers in given package
      final ResourceConfig rc = new ResourceConfig().packages("com.example")
                                                    .register(MoxyJsonFeature.class)
                                                    .register(jsonConfigResolver);

      // create and start a new instance of grizzly http server
      // exposing the Jersey application at BASE_URI
      return GrizzlyHttpServerFactory.createHttpServer(URI.create(BASE_URI), rc);
   }

Once all those are fixed...

Now you can add a method to MyResource such as:

   @POST
   @Consumes("application/json")
   @Produces("application/json")
   public MyObject postIt(MyObject obj) {
      obj.name += " world";
      return obj;
   }

given that you have a class like

   public class MyObject {
      public String name;
   }

and the conversion to-from JSON will work automagically:

curl -v -H "Content-Type: application/json" -X POST -d '{"name":"hisham"}' http://localhost:8080/myapp/myresource
> POST /myapp/myresource HTTP/1.1
> Host: localhost:40409
> User-Agent: curl/7.42.1
> Accept: */*
> Content-Type: application/json
> Content-Length: 17
>
< HTTP/1.1 200 OK
< Content-Type: application/json
< Date: Mon, 14 Dec 2015 18:23:46 GMT
< Content-Length: 23
<
{"name":"hisham world"}