servlet - HelloWorld开发者社区

思路分析：
1. 根据需求抽象出业务对象
User{
usrename;
password;
}

ShoppingCarItem{
product;
num;
}

ShoppingCar{
List
}

2. 写Servlet处理请求
...

domain:

Java代码

package cn.itcast.cd.domain;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
public class ShoppingCar {
private List list = new ArrayList();
/**
* 根据货品和数量往购物车中添加
* @param product
* @param num
*/
public void add(String product,Integer num){
ShoppingCarItem carItem = new ShoppingCarItem();
carItem.setNum(num);
carItem.setProduct(product);
carItem.setId(UUID.randomUUID().toString());
list.add(carItem);
}
/**
* 根据唯一的标示删除购物车中对应的明细
* @param id
*/
public void remove(String id){
for (ShoppingCarItem item : list) {
if(id.equals(item.getId())){
list.remove(item);
break;
}
}
}
public List getList() {
return list;
}
}
package cn.itcast.cd.domain;
public class ShoppingCarItem {
private String product;
private Integer num;
private String id; //给每一个明细生成一个唯一的id
public String getProduct() {
return product;
}
public void setProduct(String product) {
this.product = product;
}
public Integer getNum() {
return num;
}
public void setNum(Integer num) {
this.num = num;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
}
package cn.itcast.cd.domain;
public class User {
private String username;
private String password;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}

package cn.itcast.cd.domain;

import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

public class ShoppingCar {
    private List<ShoppingCarItem> list = new ArrayList<ShoppingCarItem>();
    
    /**
     * 根据货品和数量往购物车中添加
     * @param product
     * @param num
     */
    public void add(String product,Integer num){
        ShoppingCarItem carItem = new ShoppingCarItem();
        carItem.setNum(num);
        carItem.setProduct(product);
        carItem.setId(UUID.randomUUID().toString());
        list.add(carItem);
    }
    
    /**
     * 根据唯一的标示删除购物车中对应的明细
     * @param id
     */
    public void remove(String id){
        for (ShoppingCarItem item : list) {
             if(id.equals(item.getId())){
                 list.remove(item);
                 break;
             }
        }
    }    
    
    public List<ShoppingCarItem> getList() {
        return list;
    }
    
}

package cn.itcast.cd.domain;

public class ShoppingCarItem {
    private String product;
    private Integer  num;
    private String id;  //给每一个明细生成一个唯一的id
    public String getProduct() {
        return product;
    }
    public void setProduct(String product) {
        this.product = product;
    }
    public Integer getNum() {
        return num;
    }
    public void setNum(Integer num) {
        this.num = num;
    }
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    
}

package cn.itcast.cd.domain;

public class User {
    private String username;
    private String password;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
}

servlet:

Java代码

package cn.itcast.cd.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import cn.itcast.cd.domain.ShoppingCar;
public class BuyServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=utf-8");
//1. 获取请求中的参数.
String product = request.getParameter("product");
String num = request.getParameter("num");
//2. 获取到购物车
//2.1 首先要到session中找一下是否已经有了购物车. 如果有的话就不需要创建了... 直接把货品放到购物车中就可以了
HttpSession httpSession = request.getSession();
ShoppingCar shoppingCar = (ShoppingCar)httpSession.getAttribute("SHOPINGCAR_IN_SESSION");
if(shoppingCar==null){ //说明是第一次购物. 还没有购物车的
//2.2 如果从session中没有找到购物车. 需要新创建一个购物车并且放到session中.为了下次购物使用这个购物车
shoppingCar = new ShoppingCar();
httpSession.setAttribute("SHOPINGCAR_IN_SESSION", shoppingCar);
}
shoppingCar.add(product, Integer.parseInt(num));
PrintWriter pw = response.getWriter();
pw.println("添加成功
");
pw.println("继续购物
");
pw.println("管理购物
");
}
}
package cn.itcast.cd.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import cn.itcast.cd.domain.ShoppingCar;
import cn.itcast.cd.domain.ShoppingCarItem;
import cn.itcast.cd.domain.User;
public class ListServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=utf-8");
HttpSession httpSession = request.getSession();
//1. 先获取session中的User
User user = (User) httpSession.getAttribute("USER_IN_SESSION");
PrintWriter pw = response.getWriter();
pw.println("当前用户为:"+user.getUsername()+"
");
//2. 获取session的购物车
ShoppingCar shoppingCar = (ShoppingCar) httpSession.getAttribute("SHOPINGCAR_IN_SESSION");
//2.1 如果在session中购物车的话,列出购物车中的明细
if(shoppingCar!=null){
for (ShoppingCarItem item : shoppingCar.getList()) {
pw.println("货品:"+item.getProduct()+" 数量:"+item.getNum()+"
");
}
}else{
//2.2 在session中没有购物车的话.提示用户没有当前用户名购物车
pw.println("当前用户没有购物车.");
}
}
}
package cn.itcast.cd.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import cn.itcast.cd.domain.User;
public class LoginServlet extends HttpServlet {
@Override
protected void service(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=utf-8");
//1. 接收请求中的数据封装对象
String username = request.getParameter("username");
String password = request.getParameter("password");
User user = new User();
user.setPassword(password);
user.setUsername(username);
//2. 将用户方到session中供ListServlet从session中访问到User
HttpSession httpSession = request.getSession();
httpSession.setAttribute("USER_IN_SESSION", user);
PrintWriter pw = response.getWriter();
pw.println("欢迎:"+username+"
");
pw.println("购物
");
pw.println("管理购物
");
}
}

package cn.itcast.cd.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import cn.itcast.cd.domain.ShoppingCar;

public class BuyServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=utf-8");
     //1.  获取请求中的参数.
        String product = request.getParameter("product");
        String num     = request.getParameter("num");
     //2. 获取到购物车
           //2.1  首先要到session中找一下是否已经有了购物车. 如果有的话就不需要创建了... 直接把货品放到购物车中就可以了
            HttpSession httpSession = request.getSession();
            ShoppingCar shoppingCar = (ShoppingCar)httpSession.getAttribute("SHOPINGCAR_IN_SESSION");
            if(shoppingCar==null){ //说明是第一次购物. 还没有购物车的
                //2.2  如果从session中没有找到购物车. 需要新创建一个购物车并且放到session中.为了下次购物使用这个购物车
                shoppingCar = new ShoppingCar();
                httpSession.setAttribute("SHOPINGCAR_IN_SESSION", shoppingCar);
            }
            shoppingCar.add(product, Integer.parseInt(num));
            PrintWriter pw = response.getWriter();
            pw.println("添加成功<br/>");
            pw.println("<a href='/buy.html'>继续购物</a><br/>");
            pw.println("<a href='/list'>管理购物</a><br/>");
        
    }
}

package cn.itcast.cd.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import cn.itcast.cd.domain.ShoppingCar;
import cn.itcast.cd.domain.ShoppingCarItem;
import cn.itcast.cd.domain.User;

public class ListServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=utf-8");
        
        HttpSession httpSession = request.getSession();
        //1. 先获取session中的User
         User user  = (User) httpSession.getAttribute("USER_IN_SESSION");
         PrintWriter pw = response.getWriter();
         pw.println("当前用户为:"+user.getUsername()+"<br/>");
        //2. 获取session的购物车
                 ShoppingCar shoppingCar = (ShoppingCar) httpSession.getAttribute("SHOPINGCAR_IN_SESSION");
              //2.1  如果在session中购物车的话,列出购物车中的明细
                if(shoppingCar!=null){
                    for (ShoppingCarItem item : shoppingCar.getList()) {
                        pw.println("货品:"+item.getProduct()+"  数量:"+item.getNum()+"<br/>");
                    }
                }else{
                    //2.2 在session中没有购物车的话.提示用户没有当前用户名购物车
                     pw.println("当前用户没有购物车.");
                }
        
        
        
    }
}

package cn.itcast.cd.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import cn.itcast.cd.domain.User;

public class LoginServlet extends HttpServlet {

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=utf-8");
        
        //1. 接收请求中的数据封装对象
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        User user = new User();
        user.setPassword(password);
        user.setUsername(username);
        
        //2. 将用户方到session中供ListServlet从session中访问到User
        HttpSession  httpSession = request.getSession();
        httpSession.setAttribute("USER_IN_SESSION", user);
        
        PrintWriter pw = response.getWriter();
        pw.println("欢迎:"+username+"<br/>");
        pw.println("<a href='/buy.html'>购物</a><br/>");
        pw.println("<a href='/list'>管理购物</a><br/>");
    }

    
}

用户登录页面：

Html代码

<html>
<head>
<title>用户登录</title>
</head>
<body>
用户名：<input type="text" name="username">
密码：<input type="text" name="password">
<input type="submit" value="登录">
</form>
</body>
</html>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>用户登录</title>
</head>
<body>

<form action="/login" method="post">
    用户名：<input type="text" name="username"><br/>
    密码：<input type="text" name="password"><br/>
    <input type="submit" value="登录">
</form>
</body>
</html>

购买页面：

Html代码

<html>
<head>
<title>购物货品</title>
</head>
<body>
货品：<select name="product">
</select>
数量：<input type="text" name="num">
<input type="submit" value="购买">
</form>
</body>
</html>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>购物货品</title>
</head>
<body>

<form action="/buy" method="post">
    货品：<select name="product">
        <option value="鼠标">鼠标</option>
        <option value="键盘">键盘</option>
        <option value="内存">内存</option>
                  <option value="显示器">显示器</option>
    </select>  <br/>
    数量：<input type="text" name="num"><br/>
    <input type="submit" value="购买">
</form>
</body>
</html>

web.xml配置：

Xml代码

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app\_2\_5.xsd"
version="2.5">
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>cn.itcast.cd.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>BuyServlet</servlet-name>
<servlet-class>cn.itcast.cd.servlet.BuyServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>BuyServlet</servlet-name>
<url-pattern>/buy</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>ListServlet</servlet-name>
<servlet-class>cn.itcast.cd.servlet.ListServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ListServlet</servlet-name>
<url-pattern>/list</url-pattern>
</servlet-mapping>
</web-app>

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