1. 获取初始化参数

在web.xml中配置Servlet时，可以配置一些初始化参数。而在Servlet中可以通过ServletConfig接口提供的方法来取得这些参数。

index.jsp

 1 <%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8"%>
 2 <%
 3 String path = request.getContextPath();
 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 5 %>
 6 
 7 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
 8 <html>
 9   <head>
10     <base href="<%=basePath%>">
11     
12     <title>My JSP 'index.jsp' starting page</title>
13     <meta http-equiv="pragma" content="no-cache">
14     <meta http-equiv="cache-control" content="no-cache">
15     <meta http-equiv="expires" content="0">    
16     <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
17     <meta http-equiv="description" content="This is my page">
18     <!--
19     <link rel="stylesheet" type="text/css" href="styles.css">
20     -->
21   </head>
22   
23   <body>
24     <h1>获取初始化参数演示案例</h1>
25     <hr>
26     <a href = "servlet/GetInitParam">获取初始化参数</a>
27   </body>
28 </html>

web.xml

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <web-app version="2.5" 
 3     xmlns="http://java.sun.com/xml/ns/javaee" 
 4     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
 5     xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
 6     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
 7   <display-name></display-name>
 8   <servlet>
 9     <servlet-name>GetInitParam</servlet-name>
10     <servlet-class>servlet.GetInitParam</servlet-class>
11     <init-param>
12       <param-name>username</param-name>
13       <param-value>admin</param-value>
14     </init-param>
15     <init-param>
16       <param-name>password</param-name>
17       <param-value>123456</param-value>
18     </init-param>
19   </servlet>
20 
21   <servlet-mapping>
22     <servlet-name>GetInitParam</servlet-name>
23     <url-pattern>/servlet/GetInitParam</url-pattern>
24   </servlet-mapping>    
25   <welcome-file-list>
26     <welcome-file>index.jsp</welcome-file>
27   </welcome-file-list>
28 </web-app>

GetInitParam.java

 1 package servlet;
 2 
 3 import java.io.IOException;
 4 import java.io.PrintWriter;
 5 
 6 import javax.servlet.ServletException;
 7 import javax.servlet.http.HttpServlet;
 8 import javax.servlet.http.HttpServletRequest;
 9 import javax.servlet.http.HttpServletResponse;
10 
11 public class GetInitParam extends HttpServlet {
12     
13     private String username; // 用户名
14     private String password; // 密码
15 
16     public String getUsername() {
17         return username;
18     }
19 
20     public void setUsername(String username) {
21         this.username = username;
22     }
23 
24     public String getPassword() {
25         return password;
26     }
27 
28     public void setPassword(String password) {
29         this.password = password;
30     }
31 
32     /**
33      * The doGet method of the servlet. <br>
34      *
35      * This method is called when a form has its tag value method equals to get.
36      * 
37      * @param request the request send by the client to the server
38      * @param response the response send by the server to the client
39      * @throws ServletException if an error occurred
40      * @throws IOException if an error occurred
41      */
42     public void doGet(HttpServletRequest request, HttpServletResponse response)
43             throws ServletException, IOException {
44 
45         doPost(request, response);
46     }
47 
48     /**
49      * The doPost method of the servlet. <br>
50      *
51      * This method is called when a form has its tag value method equals to post.
52      * 
53      * @param request the request send by the client to the server
54      * @param response the response send by the server to the client
55      * @throws ServletException if an error occurred
56      * @throws IOException if an error occurred
57      */
58     public void doPost(HttpServletRequest request, HttpServletResponse response)
59             throws ServletException, IOException {
60 
61         response.setContentType("text/html; charset=UTF-8");
62         PrintWriter out = response.getWriter();
63         out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
64         out.println("<HTML>");
65         out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
66         out.println("  <BODY>");
67         out.println("    <h2>账号：" + this.getUsername() + "</h2>");
68         out.println("    <h2>密码：" + this.getPassword() + "</h2>");
69         out.println("  </BODY>");
70         out.println("</HTML>");
71         out.flush();
72         out.close();
73     }
74 
75     public void init() throws ServletException {
76         this.setUsername(this.getInitParameter("username"));
77         this.setPassword(this.getInitParameter("password"));
78     }
79 }

 

2. MVC设计模式

MVC模式：MVC（model、view、controller），是软件开发过程中比较流行的设计思想。旨在分离模型、控制、视图。是一种分层思想的体现。

 

3. Model2简介

 

 

4. 阶段项目

使用Servlet技术实现购物车效果。