json 打印

 JsonObject jsonObj = new JSONObject();
 jsonObj.put("success",true);
 jsonObj.put("msg","成功");

 PrintWriter out = response.getWriter();
 out.print(jsonObj);
 out.close();

后台简单代码  前台如果是ajax:

$.ajax({ url: "test.html", context: document.body, success: function(jsonObj){
        $(this).addClass("done");
      }});