Upload file on Servlet

[Magador]

In your HTML form, you just need a form with a file input and a submit button:

<form method="post" action="path/to/servlet" enctype="multipart/form-data">
    <input type="file" required name="file"/>
    <input type="submit" />
</form>

Minimal HTML for single file upload.
In the server-side using Servlet 3.0 API, some simple code are needed:

@MultipartConfig(location = "path/to/file/directory", fileSizeThreshold = maxSizeOfFileOnDisk)
@WebServlet("/path/to/servlet")
public class FileServlet extends HttpServlet {

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Part file = req.getPart("file");
        if (file != null) {
            file.write(name);
        }
    }
}

This is the minimal required code for this to work.