Creating json object in javascript and sending it to servlet

Question

i am creating json object to save data and then sending it to the servlet. But when i try to retrieve the object and display its contents in java servlet, it throws me an error saying " A JSONObject text must begin with '{' at 1 [character 2 line 1]". I do not know how to display the json object in java which is been sent from javascript. Here's what i am doing:

Javascript Code:

var arrayOfObjects = [];
arrayOfObjects.push({"divid":imageinc,"xCordinates":Xcord,"yCordinates":Ycord,"Height":canvasWidth,"Width":canvasHeight, "PageNo":pageNum});

Displaying Javascript contents:

for (var i = 0; i < arrayOfObjects.length; i++) {
var object = arrayOfObjects[i];
for (var property in object) {
    alert(property + '=' + object[property]);
}
}

Sending object to servlet with jquery Ajax:

    var param = 'objarray=' +arrayOfObjects;

    $.ajax({
      url: '/ProjectName/finalXmlServGen',
      type: 'POST', 
      dataType: 'json',  
      data: param,
      success: function(result) {
          alert('SUCCESS');
      }
    });

I get success message once i call the ajax. Now, i am receiving this object in servlet as:

String objarray = request.getParameter("objarray").toString();
try {
        JSONObject jsonObj = new JSONObject(objarray);          

        String xmlString= XML.toString(jsonObj);
        System.out.println("JSON to XML: " + xmlString);
    } catch (JSONException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

The message i see in my console is the error " A JSONObject text must begin with '{' at 1 [character 2 line 1]". How do i parse the object and form an xml or string?

Solution 1

On the Java side of things you need to convert the JSON array to a Java POJO bean first to be able to (easily) do something with it. There are multiple APIs to do this; Google GSON and Jackson are two possibilities.

Jackson is used internally by Jersey, the reference implementation of the JAX-RS API; it works very well in my experience.

Solution 2

What you build isn't a "JSON object", but a plain javascript object.

You must encode your object in JSON :

var param = '?objarray=' + JSON.stringify(arrayOfObjects);
$.ajax({
     url: '/ProjectName/finalXmlServGen'+param,
     type: 'POST', 
     dataType: 'json',  
     success: function(result) {
       alert('SUCCESS');
     }
});

Or you may let jQuery do the encoding :

$.ajax({
     url: '/ProjectName/finalXmlServGen',
     type: 'POST', 
     dataType: 'json',
     data: {objarray: arrayOfObjects}
     success: function(result) {
       alert('SUCCESS');
     }
});

Comments

[shabbir.rang]

doing this it gets me this error "404 (Servlet default is not available)" var param = 'objarray=' + JSON.stringify(arrayOfObjects); $.ajax({ url: '/ProjectName/finalXmlServGen', data: param, This works fine. I get success message. But in servlet i still receive the error that "{" part is missing. Thanks

[shabbir.rang]

Thats perfectly ok. Worked. Now how do i print this object in my java file? Thanks