Unable to send Json data from Ajax to Servlet

Question

I'm trying to send JSON data from a JavaScript function using Ajax to a Servlet.

Client side:

function addObject() {
    var data = {
        aa: "aa",
        bb: "bb"
    }
    var string = JSON.stringify(data);
    var xhttp = new XMLHttpRequest();
    xhttp.open("POST", "GalleryAdd", true);
    xhttp.setRequestHeader("Content-Type", "application/json");
    xhttp.onreadystatechange = function () {
        if (this.readyState == 4 && this.status == 200) {
            console.log("Done");
        }
    };
    console.log(string);
    xhttp.send(string);
}

Output from stringyfied data is {"aa":"aa","bb":"bb"} .

Servlet:

protected void doPost(HttpServletRequest request, HttpServletResponse response) {
    log(request.getParameter("aa"));
    log(request.getParameter("bb"));
}

Output in the logger is null and null .

Looks like JavaScript does not send data to the servlet, also if it's stringifyed correctly. Anyone?

Answer 1

Your Json object is in the body of the request therefore you need to parse the InputStream . Try this.

protected void doPost(HttpServletRequest req, HttpServletResponse resp) {
    JsonObject object = Json.createReader(req.getInputStream()).readObject();

    log(object.getString("aa"));
    log(object.getString("bb"));
}