Why request.getParameter("") return null using jquery formdata

Question

When I try to retrieve my verifyCodeActual parameter on the server, the result is null.

String code = request.getParameter("verifyCodeActual"); // This is null

But I'm posting this parameter in the body as you can see in the chrome console data :

the chrome console (data form)

Here is the relevant part of the server-side java code:

Relevant part of the server-side java code

Here is the JS ajax query:

    var formData = new FormData();

    var verifyCodeActual = $('#j_captcha').val();

    formData.append("verifyCodeActual", verifyCodeActual);

    $.ajax({
        url : (isEdit ? editShopUrl : registerShopUrl),
        type : 'POST',
        data : formData,
        contentType: "application/x-www-form-urlencoded",
        cache: false,
        processData: false,
        success ...
        }
    });

Welcome to Stack Overflow! Could you add the relevant part of your Java code? Instead of tyhe image. — Turtle, May 20 '18 at 12:27
I've not done a great deal with using a FormData object but if what I read is correct, isn't the JSON structure being received by the server more like **{"form": { "verifyCodeActual":"somevalue"}, "args":{}, etc}** meaning that you need to first fetch the **form** value then get the **verifyCodeActual** from that? — Jere, May 20 '18 at 13:46
it is my first time to use formData,i don't know how to get the form value or property — Heiku, May 20 '18 at 14:00

score 0 · Answer 1 · answered May 20 '18 at 18:28

I suspect this has something to do with your java code which doesn't even look like a servlet. You have no doPost method there. What IDE are you using?

Here's what your servlet should look like:

@WebServlet("/modifyShop")
public class ModifyShop extends HttpServlet {
    private static final long serialVersionUID = 1L;

    public ModifyShop() {
        super();
    }

    protected void doPost(HttpServletRequest request,HttpServletResponse response){

        String code = request.getParameter("verifyCodeActual");
        System.out.println(code);

    }

}

Also since you are using Jquery, you can create ajax methods with Jquery which are generally simpler. There are many different ways you can send ajax requests with Jquery and i highly recommend checking out BalusC's answer here about how to use Servlets and Ajax.

Here's an example where you can manually do it:

var verifyCodeActual = $('#j_captcha').val();
var params = {
    verifyCodeActual: verifyCodeActual
};

$.post("modifyShop", $.param(params), function(response) {
   //handle response here if you have any
});

thank for your answer，i will try to modify my js code. My IDE is intellij IDEA and i use spring instead of servlet — Heiku, May 21 '18 at 01:31
ah that would explain why your servlet doesn't look like a normal servlet. — Jonathan Laliberte, May 21 '18 at 01:41

score 0 · Answer 2 · answered May 21 '18 at 08:21

0

This will help you

Client

$.ajax({
    url : (isEdit ? editShopUrl : registerShopUrl),
    type : 'POST',
    data : {
        verifyCodeActual : $('#j_captcha').val()
    },
    contentType: "application/x-www-form-urlencoded",
    cache: false,
    processData: false,
    success ...
    }
});

Controller

@RequestMapping(value = "/modifyshop", method = RequestMethod.POST)
public @ResponseBody Map<String, Object> modifyShop(@RequestBody Object verifyCodeActual) throws Exception {

        System.out.println(verifyCodeActual);
}

answered May 21 '18 at 08:21

Devratna

938
1
7
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thank for your answer, it happened HTTP status 415 after i change code – Heiku May 21 '18 at 09:43
can you add dataType: 'json' in ajax and then try it again – Devratna May 21 '18 at 18:12

Why request.getParameter("") return null using jquery formdata

2 Answers2

Client

Controller