Question

I’m trying to get a simple object to JSON format from my Jetty server using Jersey.

I keep getting the error:

SEVERE: A message body writer for Java class my.package.resources.Album, and Java type class my.package.resources.Album, and MIME media type application/json was not found

One problem is that I’m not sure where to put the POJOMappingFeature with Jetty, I have tried the following but neither changes the error:

myServletHolder.setInitParameter("com.sun.jersey.api.json.POJOMappingFeature", "true");

and

myServletContextHandler.setInitParameter("com.sun.jersey.api.json.POJOMappingFeature", "true");

I know the basic REST functionality of Jersey is working because before I tried the JSON output I used plain text and it worked great.

Answer 1

I was super disappointed when I saw this one not answered as I’ve been fighting it all day. Finally figured it out so here’s what worked for me.

What I was doing:

    ServletHolder servletHolder = new ServletHolder(new ServletContainer(new PackagesResourceConfig("my.package.with.resources")));
    servletHolder.setInitParameter("com.sun.jersey.api.json.POJOMappingFeature", "true");

What I needed to do:

    Map<String,Object> initMap = new HashMap<String, Object>();
    initMap.put("com.sun.jersey.api.json.POJOMappingFeature", "true");
    initMap.put("com.sun.jersey.config.property.packages", "my.package.with.resources");
    ServletHolder servletHolder = new ServletHolder(new ServletContainer(new PackagesResourceConfig(initMap)));

I had to make sure to specify my Jersey packages and my POJOMappingFeature flag as init params. Hope this helps.