not able to get JSON string in servlet

Question

I am trying to pass some variables through JSON from JSP to servlet through ajax call. But i am getting null value at servlet side. Please some one help me on to find out where i am making mistake/ what i missed

//JSON	
		var masterdata = new Object();
	    masterdata.grn = $('#grn').val();
	    masterdata.pono = $('#pono').val();
	    masterdata.podt = $('#podt').val();
      
//call the servlet to insert the data only when error = 0
		if (error != 1){
			$.ajax({
				url : 'insertserv',
				type: 'POST',
				dataType: 'json',
		        data: {test : JSON.stringify(masterdata)},
		        contentType: 'application/json',
		        mimeType: 'application/json',
				success : function(data) {
							alert('Hi');
						}			
		          });
		    }
		else{
			alert("Save cannot be performed. Please check the entered data!");
		}
	  	});

public class insertserv extends HttpServlet {
	private static final long serialVersionUID = 1L;
	
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
	{
		System.out.println("I am inside insert");
		String masterdata = request.getParameter("test");
		System.out.println("masterdata :  "+masterdata);
		
		response.setContentType("text/plain");
	}
}

Ravi Pitroda · Accepted Answer · 2017-03-02 06:06:38Z

2

Replace your ajax code with my code...

//JSON	
		var masterdata = new Object();
	    masterdata.grn = $('#grn').val();
	    masterdata.pono = $('#pono').val();
	    masterdata.podt = $('#podt').val();
      
//call the servlet to insert the data only when error = 0
		if (error != 1){
			$.ajax({
				url : 'insertserv',
				type: 'POST',
				dataType: 'json',
		        data: JSON.stringify({"test" :masterdata}),
		        contentType: 'application/json',
		        mimeType: 'application/json',
				success : function(data) {
							alert('Hi');
						}			
		          });
		    }
		else{
			alert("Save cannot be performed. Please check the entered data!");
		}
	  	});

To get data in servlet

 BufferedReader br = new BufferedReader(new InputStreamReader(request.getInputStream()));
      String json = "";

            if (br != null) {
                json = br.readLine();
            }
 JSONObject wholedata= new JSONObject(json);

now the object wholedata has a your json..

if you are using JSON.stringify() then you have to use BufferedReader in servlet , You can use request.getparameter in servlet when you are passing data in URL of servlet.

answered Mar 2, 2017 at 6:06

Ravi Pitroda

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11 Comments

Jsel Over a year ago

Thanks for given me the correct path. Could you please little more clear on how should i proceed to get all variables

Ravi Pitroda Over a year ago

To get data from wholedata you can do like JSONObject testdata = wholedata.getJSONObject("test"); Then to get particular element write testdata .getString("grn"); This is only for example you can do it for all your Three varibles (grn,pono,grn)

Jsel Over a year ago

i am getting error at JSONObject wholedata= new JSONObject(json);" The constructor JSONObject(string) is undefined". and i have imported org.json.simple.*; too

Ravi Pitroda Over a year ago

hey Jsel first print the String json if it prints well then we are sure that our data is in servlet , if it doesn't print anydata then we have to optimize the code. if data will print then we can get variable's data from using code..

Jsel Over a year ago

fine. Thanks a lot for your help!

|

Jai · Accepted Answer · 2017-03-02 05:59:06Z

0

If your backend is responding with json content then only dataType:"json" works. Try change the response type:

response.setContentType("application/json");

Because your ajax is expecting json from the backend with dataType:"json",.

or vice-versa.

change the dataType to text: dataType:"text", as the response header says response.setContentType("text/plain");. But in this case you have to use JSON.parse() to parse the json string.

//JSON  
var masterdata = new Object();
masterdata.grn = $('#grn').val();
masterdata.pono = $('#pono').val();
masterdata.podt = $('#podt').val();

//call the servlet to insert the data only when error = 0
if (error != 1) {
  $.ajax({
    url: 'insertserv',
    type: 'POST',
    dataType: 'text', //<------change this
    data: {
      test: JSON.stringify(masterdata)
    },
    contentType: 'application/json',
    mimeType: 'application/json',
    success: function(data) {
      alert('Hi');
    }
  });
} else {
  alert("Save cannot be performed. Please check the entered data!");
}
});

edited Mar 2, 2017 at 5:59

answered Mar 2, 2017 at 5:53

Jai

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3 Comments

Jsel Over a year ago

changed response as application/json. still getting null

Jai Over a year ago

@Jsel i can see you are not returning a valid json instead change the dataType to text.

Jsel Over a year ago

i have modified as u mentioned in snippet. but getting same null:(

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