Implement a JSON representation of a resource with Jackson and JAXB annotated objects

We can process JavaScript Object Notation (JSON) requests and responses with JAXB annotated objects and Jackson. Jackson is the default JSON processor in WebSphere Application Server. By default, it is included in the JAX-RS runtime environment so we do not need to configure Jackson.

This task provides instructions for processing JSON requests and responses with JAXB annotated objects and Jackson.

1. Create a resource method. For the resource method to return JSON content, return an instance of a JAXB class directly or return a javax.ws.rs.core.Response object with a JAXB object as the response entity. We must also either add an @Produces("application/json") annotation, or set the Content-Type header in the Response object to be "application/json". The following example illustrates simple JSON return methods for the BookList JAXB class:

   @GET
   @Produces("application/json")
   public BookList getBookList() {
       BookList list = /* get a book list */
       return list;
   }

   or

   @GET
   @Produces("application/json")
   public javax.ws.rs.core.Response getBookList() {
       BookList list = /* get a book list */
       return Response.ok(list).type(MediaType.APPLICATION_JSON_TYPE).build();
   }

2. To return both XML and JSON objects, we can reuse the same method with minimal modification. Specify "application/xml", "application/json", and "text/xml" in the @Produces annotation. The following example illustrates a simple JSON return method that returns a BookList object for the BookList JAXB class:

   @GET
   @Produces("application/json", "application/xml", "text/xml")
   public BookList getBookList() {
       BookList list = /* get a book list */
       return list;
   }

   The following example illustrates a simple JSON return method that returns a javax.ws.rs.core.Response object for the BookList JAXB class:

   @GET
   @Produces("application/json", "application/xml", "text/xml")
   public javax.ws.rs.core.Response getBookList() {
       BookList list = /* get a book list */
       return Response.ok(list).build();
   }

   Content negotiation through the client request's Accept HTTP header helps determine whether a JSON or XML representation is returned by the resource method. Read about content negotiation for more information. By reusing the JAXB annotated objects, we can shorten the development time to serve both JSON and XML from the same code. Reusing the same model code can be beneficial if specific JSON or XML formatted output is not required.

   If we require specific XML and JSON output and cannot reuse the same JAXB annotated classes, one way to solve the problem is to use two different resource methods. The JSON resource method must be annotated with an @Produces("application/json") annotation and the XML resource method must be annotated with an @Produces("application/xml", "text/xml") annotation.

Results

You have returned a JSON representation with JAXB annotated classes through the Jackson JSON processor.

Related tasks

Use JSON content in JAX-RS application requests and responses

Use content negotiation to serve multiple content types in JAX-RS applications

Jackson JSON processor