HTML5 FormData returns null in Java Servlet request.getParameter()

Question

My view is HTML 5. I'm using FormData to make a AJAX 2 POST to a Servlet. Inside the servlet i'm trying to read request parameters. I can't see any parameters. However, Google Chrome Dev console shows the request payload. How can I get the same in Servlet code? Any help will be appreciated. Here's the code. JS code ``` var xhr = new XMLHttpRequest(); var formData = new FormData(); formData.append('firstName', 'ABC'); formData.append('lastName', 'XYZ'); xhr.open("POST", targetLocation, true); xhr.send(formData); ``` Servlet code (both parameters return `null`) ``` out.println("Hello! "+ request.getParameter("firstName")+ " "+ request.getParameter("lastName")+ ", thanks for sending your feedback." ); ``` Google Chrome Console ``` Content-Disposition: form-data; name="firstName" XYZ Content-Disposition: form-data; name="lastName" ABC ```

Accepted Answer

The HTML5 `FormData` API sends a `multipart/form-data` request. It's initially designed to be able to upload files by ajax, with the new version 2 `XMLHttpRequest`. Uploading files wasn't possible with the previous version.

The `request.getParameter()` by default recognizes `application/x-www-form-urlencoded` requests only. But you're sending a `multipart/form-data` request. You need to annotate your servlet class with `@MultipartConfig` so that you can get them by `request.getParameter()`.

```
@WebServlet
@MultipartConfig
public class YourServlet extends HttpServlet {}
```

Or, when you're still not on Servlet 3.0 yet, use Apache Commons FileUpload. For a more detailed answer on both approaches, see this: How to upload files to server using JSP/Servlet?

If you don't need to upload files at all, use the "standard" `XMLHttpRequest` approach instead.

```
var xhr = new XMLHttpRequest();
var data = "firstName=" + encodeURIComponent(firstName)
        + "&lastName=" + encodeURIComponent(lastName);
xhr.open("POST", targetLocation, true);
xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
xhr.send(data);
```

This way you don't need `@MultipartConfig` on your servlet anymore.

HTML5 FormData returns null in Java Servlet request.getParameter()

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