Pas la peine dans le serveur de changer le charset en réponse :
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String mess = "";
if (req.getParameter("mess") != null) {
mess = req.getParameter("mess");
}
JSONObject laReponse = new JSONObject();
laReponse.put("mess", "RECU:::" + mess);
//resp.setContentType("text/html; charset=UTF-8");
//resp.setContentType("application/json");
//resp.setCharacterEncoding("UTF-8");
resp.getWriter().print(laReponse.toString());
}
Côté client on peut modifier :
postDataBuilder.append("&mess=").append(URLEncoder.encode(params[1],"ISO-8859-15"));