Error parsing JSON request string

[jite eghagha]

I have the error : INFO: org.json.JSONException: A JSONObject text must begin with '{' at character 0

On netbeans 6.7.1, glassfish v3 prelude

On my client i create the json object and send it to GameServlet:

    
        function update_to_server(tank) {            
        var xmlhttp;    

        var json_tank = {   "player_id" : tank.player_id,
                            "tank_id" : tank.tank_id,
                            "lat" : tank.getLatLng().lat(),
                            "lng" : tank.getLatLng().lng(),
                            "powerbar" : tank.powerbar
        };

        if (window.XMLHttpRequest) {
            // code for IE7+, Firefox, Chrome, Opera, Safari
            xmlhttp=new XMLHttpRequest();
        } else if (window.ActiveXObject) {
            // code for IE6, IE5
            xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
        }
        else {
            alert("Your browser does not support XMLHTTP!");
        }

        xmlhttp.onreadystatechange = function() {
            if(xmlhttp.readyState==4) {
            }
        }
        alert(json_tank.lat);
        xmlhttp.open("GET","/game/GameServlet?" + escape(json_tank.toJSONString()), true);
        xmlhttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
        xmlhttp.send(null);       
    }

On the server side, i attempt to catch and parse:

    
        try {
            StringBuffer jb = new StringBuffer();
            String line = null;
            try {
                BufferedReader reader = request.getReader();
                while ((line = reader.readLine()) != null)
                  jb.append(line);
            } catch (Exception e) {System.out.println(e.toString());}

            try {
                JSONObject jsonObject = new JSONObject(jb.toString());
                int player_id = jsonObject.getInt("player_id");
                int tank_id = jsonObject.getInt("tank_id");
                int powerbar = jsonObject.getInt("powerbar");
                double lat = jsonObject.getDouble("lat");
                double lng = jsonObject.getDouble("lng");
                System.out.println("player_id" + player_id);
            } catch (Exception e) {System.out.println(e.toString()); throw new IOException("Error parsing JSON request string");}
        } finally {out.close();}

Is there a simpler way to get and parse my json object on the server.

[Bear Bibeault]

Well, what does the string being sent to the server look like? Have you checked it? Is it valid?

[jite eghagha]

It would seem that it isn't:

line 27: on my client:
toJSONString() in the alert function did nothing.

        alert(json_tank.toJSONString());
        xmlhttp.open("GET","/game/GameServlet?" + escape(json_tank.toJSONString()), true);   

the json_tank object and it's variables are fine, i checked that.

Is there a json javascript file (.js) that i must include in my header.

[Eric Pascarello]

toJSONString is not part of JavaScript so I guess you should be including some 3rd party library.

Eric

[jite eghagha]

thank you,
toJSONString() is found in the json_parse.js file; available at JSON

I suppose the issue is: how do i call this function from within newjavascript.js

my HTML page has this in it's header:

    
            <script type="text/javascript" src="json_parse.js"></script>
            <script type="text/javascript" src="newjavascript.js" type="text/javascript"></script>

BUT, and this is a major but; i came across this article which lead me to scrap using json_parse.js and use the toJSON(obj) function written by Tino Zijdel.

Bear Bibeault

Well, what does the string being sent to the server look like? Have you checked it? Is it valid?

thanks to Tino Zijdel's function,

Now my string looks like this: {"player_id":6123,"tank_id":0} ....checked and is this valid?

my error remains the same.

[Bear Bibeault]

Looks valid to me.

[jite eghagha]

thank you,

the string is valid and i got it working.

my server code looks like this:

            
String temp = request.getQueryString();
JSONObject object = new JSONObject(temp);