How do I expose data in a JSON format through a web service using Java?

Question

Is there an easy way to return data to web service clients in JSON using java? I\'m fine with servlets, spring, etc.

Answer 1

I have found google-gson compelling. It converts to JSON and back. http://code.google.com/p/google-gson/ It's very flexible and can handle complexities with objects in a straightforward manner. I love its support for generics.

/*
* we're looking for results in the form
* {"id":123,"name":thename},{"id":456,"name":theOtherName},...
*
* TypeToken is Gson--allows us to tell Gson the data we're dealing with
* for easier serialization.
*/
Type mapType = new TypeToken>>(){}.getType();

List> resultList = new LinkedList>();

for (Map.Entry pair : sortedMap.entrySet()) {
    Map idNameMap = new HashMap();
    idNameMap.put("id", pair.getKey());
    idNameMap.put("name", pair.getValue());
    resultList.add(idNameMap);
}

return (new Gson()).toJson(resultList, mapType);