Untitled

package com.model;

public class Product {
	private String productCode;
	public String getProductName() {
		return productName;
	}
	public void setProductName(String productName) {
		this.productName = productName;
	}
	public String getProductCode() {
		return productCode;
	}
	public void setProductCode(String productCode) {
		this.productCode = productCode;
	}
	private String productName;
}

package com.servlet;

import java.io.IOException;
import java.util.HashMap;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.dao.ProductDao;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.model.Product;
import com.model.ProductLine;

@WebServlet("/ProductController")
public class ProductController extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private HashMap<String, Object> JSONROOT = new HashMap<String, Object>();
	ProductDao dao;
    public ProductController() {
        super();
        dao=new ProductDao();
    }
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.getWriter().append("Served at: ").append(request.getContextPath());
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String action = request.getParameter("action");
		Gson gson = new GsonBuilder().setPrettyPrinting().create();
		response.setContentType("application/json");
		if (action != null) {
			try {
				if (action.equals("getProductLines")) {
					List<ProductLine> productlines=dao.getProductLines();
					JSONROOT.put("Result", "OK");
					JSONROOT.put("Records", productlines);
					String jsonArray = gson.toJson(JSONROOT);
					response.getWriter().print(jsonArray);
				}
				else if (action.equals("getProducts")) {
					List<Product> products=dao.getProducts(request.getParameter("productLine"));
					JSONROOT.put("Result", "OK");
					JSONROOT.put("Records", products);
					String jsonArray = gson.toJson(JSONROOT);
					response.getWriter().print(jsonArray);
				}
			}
			 catch (Exception ex) {
					JSONROOT.put("Result", "ERROR");
					JSONROOT.put("Message", ex.getMessage());
					String error = gson.toJson(JSONROOT);
					response.getWriter().print(error);
				}
		}

	}
}

	public List<Product> getProducts(String productLine) {
		List<Product> products = new ArrayList<Product>();
		String query = "SELECT productCode,productName from products where productLine=?";
		try {
			pStmt = dbConnection.prepareStatement(query);
			pStmt.setString(1, productLine);
			ResultSet rs = pStmt.executeQuery();
			while (rs.next()) {
				Product p=new Product();
				p.setProductCode(rs.getString("productCode"));
				p.setProductName(rs.getString("productName"));
				products.add(p);
			}
		} catch (SQLException e) {
			System.err.println(e.getMessage());
			return null;
		}
		return products;
	}

	<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<!------ Include the above in your HEAD tag ---------->

<!doctype html>
<html lang="en">
<head>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Fonts -->
    <link rel="dns-prefetch" href="https://fonts.gstatic.com">
    <link href="https://fonts.googleapis.com/css?family=Raleway:300,400,600" rel="stylesheet" type="text/css">


    <link rel="icon" href="Favicon.png">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
	<link rel="stylesheet" type="text/css" href="mystyle.css">
    <title>Laravel</title>
	<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
	<script>
		$(document).ready(function() {
			$.ajax({
				url : "ProductController?action=getProductLines",
				type : "post",
				success : function(data) {
					//alert(data.Records);
					$.each(data.Records,function(idx,obj){
						$("#cmbProductLines").append(new Option(obj.productLine,obj.productLine));
					})
				},
				error : function(xhr, status, error) {
					alert(error)
				}
			});
			$("#cmbProductLines").change(function(){
				$("#cmbProducts option[value]").remove();
				var productLine=$("#cmbProductLines").val();
				$.ajax({
					url : "ProductController?action=getProducts&productLine="+productLine,
					type : "post",
					success : function(data) {
						//alert(data.Records);
						$.each(data.Records,function(idx,obj){
							$("#cmbProducts").append(new Option(obj.productName,obj.productCode));
						})
					},
					error : function(xhr, status, error) {
						alert(error)
					}
				});
			});
		});
	</script>
</head>
<body>

	<nav class="navbar navbar-expand-lg navbar-light navbar-laravel">
		<div class="container">
			<a class="navbar-brand" href="#">Laravel</a>
			<button class="navbar-toggler" type="button" data-toggle="collapse"
				data-target="#navbarSupportedContent"
				aria-controls="navbarSupportedContent" aria-expanded="false"
				aria-label="Toggle navigation">
				<span class="navbar-toggler-icon"></span>
			</button>
			<div class="collapse navbar-collapse" id="navbarSupportedContent">
				<ul class="navbar-nav ml-auto">
					<li class="nav-item"><a class="nav-link" href="#">Login</a></li>
					<li class="nav-item"><a class="nav-link" href="#">Register</a>
					</li>
				</ul>

			</div>
		</div>
	</nav>
	<main class="login-form">
		<div class="container">
			<div class="row justify-content-center">
				<div class="col-md-8">
					<div class="card1">
						<div class="card1-header">Register</div>
						<div class="card1-body">
							<select id="cmbProductLines"></select>
							<select id="cmbProducts"></select>
						</div>
					</div>
				</div>
			</div>
		</div>
	</main>
</body>
</html>