servlet-intToBin

    import java.io.IOException;
    import java.io.PrintWriter;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.*;

    @WebServlet(urlPatterns = {"/ResultadoServlet"})
    public class Binario extends HttpServlet {
         @Override
         protected void doPost(HttpServletRequest request, HttpServletResponse response)
         throws ServletException, IOException {
               response.setContentType("text/html;charset=UTF-8");

               String str = request.getParameter("N1");
               if(str != null && !str.isEmpty()){
                   int number = Integer.parseInt(str);
                   String bin = Integer.toBinaryString(number);
                   try(PrintWriter out = response.getWriter()){
                       out.println( "<p>" + number + " em binário: " + bin +" </p>" );
                   }
               }
         }
    }