在Google App Engine Java中使用Ajax獲取Json數據

Question

我無法使用Json對象從java servlet的ajax請求中獲取數據。這是下面的代碼，我們在Google App Engine中使用channel api。我們需要實現聊天應用程序。

displayFriendList = function() {

                        var txt = document.createElement("div");

                        txt.innerHTML = "<p> Logged in as <b>" + userid
                                + "</b><p><hr />";
                        document.getElementById("friendlistdiv").appendChild(
                                txt);

                        var dataString ='userId='+userid;

                        $.ajax({
                            type : "POST",
                            url : "/OnlineUserServlet",
                            data : dataString,
                            success : function(html) {
                            alert(html.frndsList[0].friend);


                            }

                        });

                    };

Java Servlet代碼：

    while(friendList.hasNext()){

      friend = friendList.next() ;
      if(!friend.equals(user)){
           Map<String, String> state = new HashMap<String, String>();
          state.put("friend", friend);
          state.put("type","updateFriendList");
          state.put("message",user); 
          state1.add(state);
          message = new JSONObject(state);

            channelService.sendMessage(
                  new ChannelMessage(friend,message.toString()));

      }
      i++;

    }

    Map<String, String> statejason = new HashMap<String, String>();
    statejason.put("friendsList", state1.toString());
    //System.out.print("hello"+message.toString());
    response.setContentType("text/plain");
    response.getWriter().print(statejason.toString());
  }

Answer 1

您的響應類型應為application/json 。