java关键字“this”只能用在方法方法体内。当一个对象创建之后，java虚拟机就会给这个对象分配一个引用自身的指针，这个指针的名字就是this。只能在非静态方法中使用
package 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; public class GetInitParameterServlet extends HttpServlet { private String username;//用户名
private String password;//密码 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;
} /**
* Constructor of the object.
*/
public GetInitParameterServlet() {
super();
} /**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
} /**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { doPost(request,response);
} /**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" This is ");
out.print(this.getClass());
out.println(", using the POST method");
out.println("<h2>"+"用户名："+this.getUsername()+"</h2>");
out.println("<h2>"+"密码："+this.getPassword()+"</h2>");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
} /**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
this.setUsername(this.getInitParameter("username"));
this.setPassword(this.getInitParameter("password"));
} }
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
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">
<display-name></display-name>
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>GetInitParameterServlet</servlet-name>
<servlet-class>servlet.GetInitParameterServlet</servlet-class>
<init-param>
<param-name>username</param-name>
<param-value>admin</param-value>
</init-param>
<init-param>
<param-name>password</param-name>
<param-value>123456</param-value>
</init-param>
</servlet> <servlet-mapping>
<servlet-name>GetInitParameterServlet</servlet-name>
<url-pattern>/servlet/GetInitParameterServlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
<%@ page language="java" import="java.util.*" contentType="text/html;charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>"> <title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head> <body>
<h1>获取初始化参数演示案例</h1>
<hr>
<a href="servlet/GetInitParameterServlet">获取初始化参数servlet</a>
</body>
</html>
设计类的时候主要考虑两方面因素：设计这个类的属性和方法
entity：实体层
集合类型：序列、set、hashset
购买商品的集合：用Map类型表示购买商品的集合，键：商品对象，值：商品购买的数量
键：Items商品类型，值：Integer购买的数量
代码实现：
package entity; import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set; //购物车类
public class Cart {
//购买商品的集合
private HashMap<Items,Integer> goods;
//购物车的总金额
private double totalPrice;
//构造方法
public Cart() {
//初始化属性
goods = new HashMap<Items,Integer>();
totalPrice=0.0;
}
public HashMap<Items, Integer> getGoods() {
return goods;
}
public void setGoods(HashMap<Items, Integer> goods) {
this.goods = goods;
}
public double getTotalPrice() {
return totalPrice;
}
public void setTotalPrice(double totalPrice) {
this.totalPrice = totalPrice;
} //添加商品进购物车的方法
public boolean addGoodsInCart(Items item,int number)//参数：商品对象item，商品数量number
{//判断购物车是否包含该商品
if(goods.containsKey(item))//如果此映射包含对于指定键的映射关系，则返回 true。
{
goods.put(item, goods.get(item)+number);//在此映射中关联指定值与指定键。
}
else{//第一次购买这个商品
goods.put(item, number);
}
//当你添加和删除商品之后，都应该重新计算购物车的总金额
calTotalPrice();//重新计算购物车的总金额
return true;
} //删除商品的方法
public boolean removeGoodsFromCart(Items item)
{
goods.remove(item);//从此映射中移除指定键的映射关系（如果存在）。
calTotalPrice();//重新计算购物车的总金额
return true;
} //统计购物车的总金额
public double calTotalPrice(){ double sum=0.0;
//遍历Map类型的集合
Set<Items> keys=goods.keySet();//获得键的集合
//set类型用for循环是没法遍历的，必须使用迭代器
Iterator<Items> it=keys.iterator();//获得迭代器对象
//Iterator用while遍历
while(it.hasNext()){
//遍历商品对象
Items i=it.next();
//计算总价格：单价*购买数量
sum+=i.getPrice()*goods.get(i);//调用get方法取得每个键对应的value
}
this.setTotalPrice(sum);//设置购物车的总金额
return this.getTotalPrice();//返回总金额
}
public static void main(String[] args){
//先创建两个商品对象
Items i1 = new Items(1,"沃特篮球鞋","温州",200,500,"001.jpg");
Items i2 = new Items(2,"李宁运动鞋","广州",300,500,"002.jpg");
Items i3 = new Items(1,"沃特篮球鞋","温州",200,500,"001.jpg"); Cart c = new Cart();
c.addGoodsInCart(i1, 1);
c.addGoodsInCart(i2, 2);
//再次购买沃特篮球鞋，购买3双
c.addGoodsInCart(i3, 3); // 通过entrySet方法，返回Map中的所有键值对
//遍历购物商品的集合
Set<Map.Entry<Items, Integer>> items= c.getGoods().entrySet();//Entry<Items, Integer>键值对对象
for(Map.Entry<Items, Integer> obj:items)
{
System.out.println(obj);
} System.out.println("购物车的总金额："+c.getTotalPrice());
} }
重写Items类中的两个方法：equals(Object)，hashCode()
//改写hashCode生成规则
@Override
public int hashCode() {//hashCode是这个对象的哈希码
// TODO Auto-generated method stub
return this.getId()+this.getName().hashCode();//商品的编号、商品的名称如果这两个都相同，那生成的hashCode也相同（相同的字符串，hashCode也相同）
} //判断这两个对象的内容是否相同
@Override
public boolean equals(Object obj) {
// 如果当前对象就等于传进来的对象，则这是两个相同的对象
if(this==obj){
return true;
} //判断是否属于商品类
if(obj instanceof Items){//使用 instanceof 判断一个实例是否属于某种类型
Items i=(Items)obj;
//判断商品编号和商品名称都和当前商品完全一样的话,要比较的商品对象和我自身的这个对象它的内容是相同的
if(this.getId()==i.getId()&&this.getName().equals(i.getName())){
return true;
}
else
{
return false;
}
}
else{
return false;
}
}
编写Servlet：添加商品进购物车
path是项目的根目录，服务器的根目录：WebRoot
代码实现：
package 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 dao.ItemsDAO;
import entity.Cart;
import entity.Items; public class CartServlet extends HttpServlet { private String action ; //表示购物车的动作 ,add,show,delete
//商品业务逻辑类的对象
private ItemsDAO idao = new ItemsDAO(); /**
* Constructor of the object.
*/
public CartServlet() {
super();
} /**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
} /**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
} /**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
if(request.getParameter("action")!=null)
{
this.action = request.getParameter("action");
if(action.equals("add")) //如果是添加商品进购物车
{
if(addToCart(request,response))
{
request.getRequestDispatcher("/success.jsp").forward(request, response);
}
else
{
request.getRequestDispatcher("/failure.jsp").forward(request, response);
}
}
if(action.equals("show"))//如果是显示购物车
{
request.getRequestDispatcher("/cart.jsp").forward(request, response);
}
if(action.equals("delete")) //如果是执行删除购物车中的商品
{
if(deleteFromCart(request,response))
{
request.getRequestDispatcher("/cart.jsp").forward(request, response);
}
else
{
request.getRequestDispatcher("/cart.jsp").forward(request, response);
}
}
} } //添加商品进购物车的方法
private boolean addToCart(HttpServletRequest request, HttpServletResponse response)
{//商品id
String id = request.getParameter("id");
//商品数量
String number = request.getParameter("num");
//商品资料
Items item = idao.getItemsById(Integer.parseInt(id));//Integer.parseInt(id)转换成整型 //是否是第一次给购物车添加商品,需要给session中创建一个新的购物车对象
if(request.getSession().getAttribute("cart")==null)
{
Cart cart = new Cart();
//填到session当中
request.getSession().setAttribute("cart",cart);
}
//获得session对象
Cart cart = (Cart)request.getSession().getAttribute("cart");
if(cart.addGoodsInCart(item, Integer.parseInt(number)))//Integer.parseInt(number)字符串类型强转成int类型
{
return true;
}
else
{
return false;
} } //从购物车中删除商品
private boolean deleteFromCart(HttpServletRequest request, HttpServletResponse response)
{
String id = request.getParameter("id");
Cart cart = (Cart)request.getSession().getAttribute("cart");
Items item = idao.getItemsById(Integer.parseInt(id));
if(cart.removeGoodsFromCart(item))
{
return true;
}
else
{
return false;
}
} /**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
} }
detail.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8" %>
<%@ page import="entity.Items"%>
<%@ page import="dao.ItemsDAO"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>"> <title>My JSP 'details.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<link href="css/main.css" rel="stylesheet" type="text/css">
<script type="text/javascript" src="js/lhgcore.js"></script>
<script type="text/javascript" src="js/lhgdialog.js"></script>
<script type="text/javascript">
function selflog_show(id)//id要购买的商品编号 ，num购买商品数量，&action=add添加商品进购物车，path是项目的根目录，服务器的根目录：WebRoot
{
var num = document.getElementById("number").value;
J.dialog.get({id: 'haoyue_creat',title: '购物成功',width: 600,height:400, link: '<%=path%>/servlet/CartServlet?id='+id+'&num='+num+'&action=add', cover:true});
}
function add()
{
var num = parseInt(document.getElementById("number").value);
if(num<100)
{
document.getElementById("number").value = ++num;
}
}
function sub()
{
var num = parseInt(document.getElementById("number").value);
if(num>1)
{
document.getElementById("number").value = --num;
}
} </script> <style type="text/css">
hr{ border-color:FF7F00;
} div{
float:left;
margin-left: 30px;
margin-right:30px;
margin-top: 5px;
margin-bottom: 5px; }
div dd{
margin:0px;
font-size:10pt;
}
div dd.dd_name
{
color:blue;
}
div dd.dd_city
{
color:#000;
}
div #cart
{
margin:0px auto;
text-align:right;
}
span{
padding:0 2px;border:1px #c0c0c0 solid;cursor:pointer;
}
a{
text-decoration: none;
}
</style>
</head> <body>
<h1>商品详情</h1>
<a href="index.jsp">首页</a> >> <a href="index.jsp">商品列表</a>
<hr>
<center>
<table width="750" height="60" cellpadding="0" cellspacing="0" border="0">
<tr>
<!-- 商品详情 -->
<%
ItemsDAO itemDao = new ItemsDAO();
Items item = itemDao.getItemsById(Integer.parseInt(request.getParameter("id")));
if(item!=null)
{
%>
<td width="70%" valign="top">
<table>
<tr>
<td rowspan="5"><img src="data:images/<%=item.getPicture()%>" width="200" height="160"/></td>
</tr>
<tr>
<td><B><%=item.getName() %></B></td>
</tr>
<tr>
<td>产地：<%=item.getCity()%></td>
</tr>
<tr>
<td>价格：<%=item.getPrice() %>￥</td>
</tr>
<tr>
<td>购买数量：<span id="sub" onclick="sub();">-</span><input type="text" id="number" name="number" value="1" size="2"/><span id="add" onclick="add();">+</span></td>
</tr>
</table>
<div id="cart">
<img src="data:images/buy_now.png"><a href="javascript:selflog_show(<%=item.getId()%>)"><img src="data:images/in_cart.png"></a><a href="servlet/CartServlet?action=show"><img src="data:images/view_cart.jpg"/></a>
</div>
</td>
<%
}
%>
<%
String list ="";
//从客户端获得Cookies集合
Cookie[] cookies = request.getCookies();
//遍历这个Cookies集合
if(cookies!=null&&cookies.length>0)
{
for(Cookie c:cookies)
{
if(c.getName().equals("ListViewCookie"))
{
list = c.getValue();
}
}
} list+=request.getParameter("id")+",";
//如果浏览记录超过1000条，清零.
String[] arr = list.split(",");
if(arr!=null&&arr.length>0)
{
if(arr.length>=1000)
{
list="";
}
}
Cookie cookie = new Cookie("ListViewCookie",list);
response.addCookie(cookie); %>
<!-- 浏览过的商品 -->
<td width="30%" bgcolor="#EEE" align="center">
<br>
<b><font color="#FF7F00">您浏览过的商品</font></b><br>
<!-- 循环开始 -->
<%
ArrayList<Items> itemlist = itemDao.getViewList(list);
if(itemlist!=null&&itemlist.size()>0 )
{
System.out.println("itemlist.size="+itemlist.size());
for(Items i:itemlist)
{ %>
<div>
<dl>
<dt>
<a href="details.jsp?id=<%=i.getId()%>"><img src="data:images/<%=i.getPicture() %>" width="120" height="90" border="1"/></a>
</dt>
<dd class="dd_name"><%=i.getName() %></dd>
<dd class="dd_city">产地:<%=i.getCity() %> 价格:<%=i.getPrice() %> ￥ </dd>
</dl>
</div>
<%
}
}
%>
<!-- 循环结束 -->
</td>
</tr>
</table>
</center>
</body>
</html>
success.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8" %>
<%@ page import="entity.Items"%>
<%@ page import="dao.ItemsDAO"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>"> <title>My JSP 'details.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
<link href="css/main.css" rel="stylesheet" type="text/css">
<script type="text/javascript" src="js/lhgcore.js"></script>
<script type="text/javascript" src="js/lhgdialog.js"></script>
<script type="text/javascript">
function selflog_show(id)//id要购买的商品编号 ，num购买商品数量，&action=add添加商品进购物车，path是项目的根目录，服务器的根目录：WebRoot
{
var num = document.getElementById("number").value;
J.dialog.get({id: 'haoyue_creat',title: '购物成功',width: 600,height:400, link: '<%=path%>/servlet/CartServlet?id='+id+'&num='+num+'&action=add', cover:true});
}
function add()
{
var num = parseInt(document.getElementById("number").value);
if(num<100)
{
document.getElementById("number").value = ++num;
}
}
function sub()
{
var num = parseInt(document.getElementById("number").value);
if(num>1)
{
document.getElementById("number").value = --num;
}
} </script> <style type="text/css">
hr{ border-color:FF7F00;
} div{
float:left;
margin-left: 30px;
margin-right:30px;
margin-top: 5px;
margin-bottom: 5px; }
div dd{
margin:0px;
font-size:10pt;
}
div dd.dd_name
{
color:blue;
}
div dd.dd_city
{
color:#000;
}
div #cart
{
margin:0px auto;
text-align:right;
}
span{
padding:0 2px;border:1px #c0c0c0 solid;cursor:pointer;
}
a{
text-decoration: none;
}
</style>
</head> <body>
<h1>商品详情</h1>
<a href="index.jsp">首页</a> >> <a href="index.jsp">商品列表</a>
<hr>
<center>
<table width="750" height="60" cellpadding="0" cellspacing="0" border="0">
<tr>
<!-- 商品详情 -->
<%
ItemsDAO itemDao = new ItemsDAO();
Items item = itemDao.getItemsById(Integer.parseInt(request.getParameter("id")));
if(item!=null)
{
%>
<td width="70%" valign="top">
<table>
<tr>
<td rowspan="5"><img src="data:images/<%=item.getPicture()%>" width="200" height="160"/></td>
</tr>
<tr>
<td><B><%=item.getName() %></B></td>
</tr>
<tr>
<td>产地：<%=item.getCity()%></td>
</tr>
<tr>
<td>价格：<%=item.getPrice() %>￥</td>
</tr>
<tr>
<td>购买数量：<span id="sub" onclick="sub();">-</span><input type="text" id="number" name="number" value="1" size="2"/><span id="add" onclick="add();">+</span></td>
</tr>
</table>
<div id="cart">
<img src="data:images/buy_now.png"><a href="javascript:selflog_show(<%=item.getId()%>)"><img src="data:images/in_cart.png"></a><a href="servlet/CartServlet?action=show"><img src="data:images/view_cart.jpg"/></a>
</div>
</td>
<%
}
%>
<%
String list ="";
//从客户端获得Cookies集合
Cookie[] cookies = request.getCookies();
//遍历这个Cookies集合
if(cookies!=null&&cookies.length>0)
{
for(Cookie c:cookies)
{
if(c.getName().equals("ListViewCookie"))
{
list = c.getValue();
}
}
} list+=request.getParameter("id")+",";
//如果浏览记录超过1000条，清零.
String[] arr = list.split(",");
if(arr!=null&&arr.length>0)
{
if(arr.length>=1000)
{
list="";
}
}
Cookie cookie = new Cookie("ListViewCookie",list);
response.addCookie(cookie); %>
<!-- 浏览过的商品 -->
<td width="30%" bgcolor="#EEE" align="center">
<br>
<b><font color="#FF7F00">您浏览过的商品</font></b><br>
<!-- 循环开始 -->
<%
ArrayList<Items> itemlist = itemDao.getViewList(list);
if(itemlist!=null&&itemlist.size()>0 )
{
System.out.println("itemlist.size="+itemlist.size());
for(Items i:itemlist)
{ %>
<div>
<dl>
<dt>
<a href="details.jsp?id=<%=i.getId()%>"><img src="data:images/<%=i.getPicture() %>" width="120" height="90" border="1"/></a>
</dt>
<dd class="dd_name"><%=i.getName() %></dd>
<dd class="dd_city">产地:<%=i.getCity() %> 价格:<%=i.getPrice() %> ￥ </dd>
</dl>
</div>
<%
}
}
%>
<!-- 循环结束 -->
</td>
</tr>
</table>
</center>
</body>
</html>
failure.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>"> <title>My JSP 'success.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
--> </head> <body>
<center>
<img src="data:images/add_cart_failure.jpg"/>
<hr> <br>
<br>
<br> </center>
</body>
</html>
显示购物车
商品删除
带有确认功能的对话框
