JSP + JavaBean + Servlet实现MVC设计模式
1、流程图：
2、代码清单
数据库脚本：
1 DROP TABLE IF EXISTS `user`;
2
3 CREATE TABLE `user` (
4 `userid` varchar(30) NOT NULL,
5 `name` varchar(30) NOT NULL,
6 `password` varchar(30) NOT NULL,
7 PRIMARY KEY (`userid`)
8 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
9
10 INSERT INTO `user` VALUES ('admin', 'administrator', 'admin');
User 类：
View CodeDatabaseConnection 类：
1 package com.shawn.mvcdemo.dbc;
2
3 import java.sql.*;
4
5 public class DatabaseConnection{
6 private static final String DBDRIVER = "org.gjt.mm.mysql.Driver"; //数据库驱动
7 private static final String DBURL = "jdbc:mysql://localhost:3306/mldn"; //数据库URL
8 private static final String DBUSER = "root"; //用户名
9 private static final String DBPASSWORD = "root"; //密码
10
11 private Connection conn = null;
12
13 public DatabaseConnection() throws Exception{
14 try{
15 Class.forName(DBDRIVER);
16 this.conn = DriverManager.getConnection(DBURL,DBUSER,DBPASSWORD);
17 } catch(Exception e){
18 throw e;
19 }
20 }
21
22 public Connection getConnection(){
23 return this.conn;
24 }
25
26 public void close() throws Exception{
27 if(this.conn != null){
28 try{
29 this.conn.close();
30 } catch(Exception e){
31 throw e;
32 }
33 }
34 }
35
36 public static void main(String args[]){
37 try{
38 System.out.println(new DatabaseConnection().getConnection());
39 } catch(Exception e){
40 e.printStackTrace();
41 }
42 }
43 }
IUserDAO 接口：
1 package com.shawn.mvcdemo.dao;
2
3 import com.shawn.mvcdemo.vo.User;
4
5 public interface IUserDAO{
6 //现在完成的是登录验证，那么登录操作只有两种返回结果
7 public boolean findLogin(User user) throws Exception;
8 }
UserDAOImpl 类：
1 package com.shawn.mvcdemo.dao.impl;
2
3 import java.sql.*;
4
5 import com.shawn.mvcdemo.vo.User;
6 import com.shawn.mvcdemo.dbc.*;
7 import com.shawn.mvcdemo.dao.*;
8
9 public class UserDAOImpl implements IUserDAO{
10 private Connection conn = null;
11
12 private PreparedStatement pstmt = null;
13
14 public UserDAOImpl(Connection conn){
15 this.conn = conn;
16 }
17
18 public boolean findLogin(User user) throws Exception{
19 boolean flag = false;
20 String sql = "select name from user where userid = ? and password = ?";
21 this.pstmt = this.conn.prepareStatement(sql);
22 this.pstmt.setString(1,user.getUserID());
23 this.pstmt.setString(2,user.getPassword());
24 ResultSet rs = this.pstmt.executeQuery();
25 if(rs.next()){
26 user.setName(rs.getString("name"));
27 flag = true;
28 }
29 this.pstmt.close();
30 return flag;
31 }
32 }
UserDAOProxy 类：
1 package com.shawn.mvcdemo.dao.proxy;
2
3 import java.sql.*;
4
5 import com.shawn.mvcdemo.vo.User;
6 import com.shawn.mvcdemo.dbc.*;
7 import com.shawn.mvcdemo.dao.*;
8 import com.shawn.mvcdemo.dao.impl.*;
9
10 public class UserDAOProxy implements IUserDAO{
11 private DatabaseConnection dbc = null;
12 private IUserDAO dao = null;
13
14 public UserDAOProxy(){
15 try{
16 this.dbc = new DatabaseConnection();
17 } catch(Exception e){
18 e.printStackTrace();
19 }
20 this.dao = new UserDAOImpl(this.dbc.getConnection());
21 }
22
23 public boolean findLogin(User user) throws Exception{
24 boolean flag = false;
25 try{
26 flag = this.dao.findLogin(user); //调用真实主题，完成操作
27 } catch(Exception e){
28 throw e;
29 } finally{
30 this.dbc.close();
31 }
32 return flag;
33 }
34
35
36 }
DAOFactory 类：
1 package com.shawn.mvcdemo.factory;
2
3 import com.shawn.mvcdemo.dao.*;
4 import com.shawn.mvcdemo.dao.proxy.*;
5
6 public class DAOFactory{
7 public static IUserDAO getIUserDAOInstance(){
8 return new UserDAOProxy();
9 }
10 }
LoginServlet 类：
1 package com.shawn.mvcdemo.servlet;
2
3 import java.io.*;
4 import java.util.*;
5
6 import javax.servlet.*;
7 import javax.servlet.http.*;
8 import com.shawn.mvcdemo.factory.*;
9 import com.shawn.mvcdemo.vo.*;
10
11 public class LoginServlet extends HttpServlet{
12
13 public void doGet(HttpServletRequest req,HttpServletResponse resp)
14 throws ServletException,IOException{
15 String path = "login.jsp";
16 String userID = req.getParameter("userID");
17 String password = req.getParameter("password");
18 List<String> info = new ArrayList<String>();//收集错误信息
19 if(userID == null || "".equals(userID)){
20 info.add("用户id不能为空！");
21 }
22 if(password == null || "".equals(password)){
23 info.add("密码不能为空！");
24 }
25 if(info.size() == 0){//里面没有记录任何的错误
26 User user = new User();
27 user.setUserID(userID);
28 user.setPassword(password);
29 try{
30 if(new DAOFactory().getIUserDAOInstance().findLogin(user)){
31 info.add("用户登陆成功，欢迎" + user.getName() + "光临！");
32 System.out.println(1);
33 } else {
34 info.add("用户登录失败，错误的用户名和密码！");
35 System.out.println(2);
36 }
37 }catch(Exception e){
38 e.printStackTrace();
39 }
40 }
41 req.setAttribute("info",info);
42 req.getRequestDispatcher(path).forward(req,resp);
43 }
44
45 public void doPost(HttpServletRequest req,HttpServletResponse resp)
46 throws ServletException,IOException{
47 this.doGet(req,resp);
48 }
49
50 }
login.jsp 页面：
1 <%@ page contentType="text/html" pageEncoding="utf-8" import="java.util.*"%>
2 <html>
3 <head>
4 <title>www.mldnjava.cn, MLDN高端Java培训</title>
5 <%
6 request.setCharacterEncoding("utf-8");
7 %>
8 <%
9 List<String> info = (ArrayList<String>)request.getAttribute("info");
10 String userID = request.getParameter("userID");
11 String password = request.getParameter("password");
12 %>
13 <script>
14 window.onload = function(){
15 var objForm = document.getElementById("form1");
16
17 objForm.onsubmit = function(){
18 if(!(/^\w{5,15}$/.test(this.userID.value))){
19 alert("用户ID必须是5~15位！");
20 this.userID.focus();
21 return false;
22 }
23
24 if(!(/^\w{5,15}$/.test(this.password.value))){
25 alert("密码必须是5~15位！");
26 this.password.focus();
27 return false;
28 }
29 }
30
31 }
32
33 </script>
34 </head>
35
36 <body>
37 <form id="form1" action="login" method="post">
38 用户ID：<input type="text" name="userID" value="<%= (userID == null) ? "" : userID %>" /><br>
39 密 码：<input type="password" name="password" value="<%= (password == null) ? "" : password %>" /><br>
40 <input type="submit" value="登录" />
41 <input type="reset" value="重置" />
42 </form>
43 <%
44 if(info != null){
45 for(String str : info){
46 %>
47 <h3><%=str %></h3>
48 <%
49 }
50 }
51 %>
52 </body>
53 </html>
web.xml 配置：
1 <?xml version="1.0" encoding="ISO-8859-1"?> 2 3 <web-app 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 http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 6 version="2.5"> 7 8 <display-name>Hello World!</display-name> 9 <welcome-file-list> 10 <welcome-file>main.html</welcome-file> 11 </welcome-file-list> 12 13 <servlet> 14 <servlet-name>login</servlet-name> 15 <servlet-class>com.shawn.mvcdemo.servlet.LoginServlet</servlet-class> 16 </servlet> 17 18 <servlet-mapping> 19 <servlet-name>login</servlet-name> 20 <url-pattern>/mvclogin/login</url-pattern> 21 </servlet-mapping> 22 </web-app>