HttpClient
Tue, Dec 28, 2021
3-minute read
create product class
package appShop;
public class Product {
private int id;// productid
private String name;//
private String description;//
private float price;//
public Product(int id,String name,String description,float price){
this.setId(id);
this.setName(name);
this.setDescription(description);
this.setPrice(price);
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public float getPrice() {
return price;
}
public void setPrice(float price) {
this.price = price;
}
}
create shoppingItem class
package appshop
public class ShoppingItem {
private Product product;
private int quantity;
public ShoppingItem(Product product, int quantity){
this.setProduct(product);
this.setQuantity(quantity);
}
public Product getProduct() {
return product;
}
public void setProduct(Product product) {
this.product = product;
}
public int getQuantity() {
return quantity;
}
public void setQuantity(int quantity) {
this.quantity = quantity;
}
}
```java
package appShop;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.NumberFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
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 javax.servlet.http.HttpSession;
@WebServlet(name="ShoppingCartServlet",urlPatterns={"/products","/viewProductDetails","/addToCart","/viewCart"})
public class ShoppingCartServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final String CART_ATTRIBUTE = "cart";
private List<Product> products = new ArrayList<Product>();
private NumberFormat currencyFormat = NumberFormat.getCurrencyInstance(Locale.US);
//init four productions with details
@Override
public void init() throws ServletException {
products.add(new Product(1,"A","XXXXX",1000$));
products.add(new Product(2,"B","XXXX",2000$));
products.add(new Product(3,"C","XXXXXX",3000$));
products.add(new Product(4,"D","XXX",40000$));
}
}
}
//URL doGet method,
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String uri=req.getRequestURI();
if(uri.endsWith("/products")){
sendProductList(resp);
}else if(uri.endsWith("/viewProductDetails")){
sendProductDetails(req,resp);
}else if(uri.endsWith("/viewCart")){
showCart(req,resp);
}
}
// when clients click buy, get those request, add product and quantity into cart
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
int quantity = 0;
int productId = 0;
try {
productId = Integer.parseInt(req.getParameter("id"));
quantity = Integer.parseInt(req.getParameter("quantity"));
} catch(NumberFormatException e){ }
Product product = getProduct(productId);
if(product != null && quantity > 0) {
ShoppingItem shoppingItem = new ShoppingItem(product, quantity);
HttpSession session = req.getSession();
List<ShoppingItem> cart = (List<ShoppingItem)session.getAttribute(CART_ATTRIBUTE);
if(cart==null){
cart=new ArrayList<ShoppingItem>();
session.setAttribute(CART_ATTRIBUTE, cart);
}
cart.add(shoppingItem);
}
// if the product is null, then send the productlist
sendProductList(resp);
}
//send the productList
private void sendProductList(HttpServletResponse response) throws IOException{
response.getContentType("text/html");
PrintWriter writer = response.getWriter();
write.println("<html><head><title>Products</title>"+
"</head><body><h2>Products</h2>");
write.println("<ul>");
//list product list
for (Product product : products) {
write.println("<li>"+product.getName()+"("+currencyFormat.format(product.getPrice())
+") ("+"<a href='viewProductDetails?id="+product.getId()+"'>Details</a>)");
}
write.println("</ul>");
write.println("<a href='viewCart'>View Cart</a>");
write.println("</body></html>");
}
private Product getProduct(int productId) {
for(Product product:products){
if(product.getId()==productId){
return product;
}
}
return null;
}
// send the productdetails
//发送产品描述
private void sendProductDetails(HttpServletRequest req,
HttpServletResponse resp) throws IOException {
resp.setContentType("text/html");
PrintWriter write=resp.getWriter();
int productId=0;
try{
productId=Integer.parseInt(req.getParameter("id"));
}catch(NumberFormatException e){}
Product product =getProduct(productId);
if(product!=null){
write.println("<html><head>"
+"<title>Product Details</title></head>"
+"<body><h2>Product Details</h2>"
+"<form method='post' action='addToCart'>");
write.println("<input type='hidden' name='id' "
+"value=' "+productId+" '/>");
write.println("<table>");
write.println("<tr><td>Name:</td><td>"
+product.getName()+"</td></tr>");
write.println("<tr><td>Description:</td><td>"
+product.getDescription()+"</td></tr>");
write.println("<tr>"+"<tr>"
+"<td><input name='quantity' ></td>"
+"<td><input type='submit' value='buy'></td>"
+"</tr>");
write.println("<tr><td colspan='2'>"
+"<a href='products'>Product List</a>"
+"</td></tr>");
write.println("</table>");
write.println("</form></body>");
}else{
write.println("No product found");
}
}
//show the shopping cart
private void showCart(HttpServletRequest req, HttpServletResponse resp) throws IOException {
resp.setContentType("text/html");
PrintWriter writer=resp.getWriter();
writer.println("<html><head><title>Shopping Cart</title></head>");
writer.println("<body><a href='products'>Product List</a>");
HttpSession session=req.getSession();
List<ShoppingItem> cart=(List<ShoppingItem>)
session.getAttribute(CART_ATTRIBUTE);
if(cart!=null){
writer.println("<table>");
writer.println("<tr>"
+"<td style='width:150px'>Quantity</td>"
+"<td style='width:150px'>Product</td> "
+"<td style='width:150px'>Price</td>"
+"<td>Amount</td></tr>");
double total=0.0;
for(ShoppingItem shoppingItem:cart){
Product product=shoppingItem.getProduct();
int quantity=shoppingItem.getQuantity();
if(quantity!=0){
float price=product.getPrice();
writer.println("<tr>"
+"<td>"+quantity+"</td>"
+"<td>"+product.getName()+"</td>"
+"<td>"+currencyFormat.format(price)+"</td>");
double subtotal=price*quantity;
writer.println("<td>"+currencyFormat.format(subtotal));
total+=subtotal;
writer.println("</tr>");
}
}
writer.println("<tr><td colspan='4'>"
+"style='text-align:right'>"
+"Total:"
+currencyFormat.format(total)
+"</td></tr>");
writer.println("</table>");
}
writer.println("</table></body></html>");
}
