Question

I am trying to encode a JSP servlet into JSON. What’s the equivalent in JSP to json_encode() in PHP ?

Answer 1

JSP/Servlet isn’t that high-level as PHP which has practically “anything built-in”. In Java you’ve more freedom to choose from libraries. There are several JSON libraries in Java available which you can implement in your webapp, the popular ones being under each JSON.org, Jackson and Google Gson.

We use here Gson to our satisfaction. It has excellent support for parameterized collections and (nested) Javabeans. It’s basically as simple as follows:

String json = new Gson().toJson(anyObject); // anyObject = List<Bean>, Map<K, Bean>, Bean, String, etc..
response.setContentType("application/json");
response.setCharacterEncoding("UTF-8");
response.getWriter().write(json);

Converting JSON to a fullworthy Javabean is also simple with Gson, see this example.