JSP + JavaBean + Servlet实现MVC设计模式

1、流程图：

2、代码清单

数据库脚本：

 DROP TABLE IF EXISTS `user`;

 CREATE TABLE `user` (
   `userid` varchar(30) NOT NULL,
   `name` varchar(30) NOT NULL,
   `password` varchar(30) NOT NULL,
   PRIMARY KEY  (`userid`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

 INSERT INTO `user` VALUES ('admin', 'administrator', 'admin');

User 类：

 package com.shawn.mvcdemo.vo;

 public class User{
     private String userID;

     private String name;

     private String password;

     public String getUserID(){
         return this.userID;
     }

     public String getName(){
         return this.name;
     }

     public String getPassword(){
         return this.password;
     }

     public void setUserID(String userID){
         this.userID = userID;
     }

     public void setName(String name){
         this.name = name;
     }

     public void setPassword(String password){
         this.password = password;
     }

 }

DatabaseConnection 类：

 package com.shawn.mvcdemo.dbc;

 import java.sql.*;

 public class DatabaseConnection{
     private static final String DBDRIVER = "org.gjt.mm.mysql.Driver";    //数据库驱动
     private static final String DBURL = "jdbc:mysql://localhost:3306/mldn";    //数据库URL
     private static final String DBUSER = "root";    //用户名
     private static final String DBPASSWORD = "root";    //密码

     private Connection conn = null;

     public DatabaseConnection() throws Exception{
         try{
             Class.forName(DBDRIVER);
             this.conn = DriverManager.getConnection(DBURL,DBUSER,DBPASSWORD);
         } catch(Exception e){
             throw e;
         }
     }

     public Connection getConnection(){
         return this.conn;
     }

     public void close() throws Exception{
         if(this.conn != null){
             try{
                 this.conn.close();
             } catch(Exception e){
                 throw e;
             }
         }
     }

     public static void main(String args[]){
         try{
             System.out.println(new DatabaseConnection().getConnection());
         } catch(Exception e){
             e.printStackTrace();
         }
     }
 }

IUserDAO 接口：

 package com.shawn.mvcdemo.dao;

 import com.shawn.mvcdemo.vo.User;

 public interface IUserDAO{
     //现在完成的是登录验证，那么登录操作只有两种返回结果
     public boolean findLogin(User user) throws Exception;
 }

UserDAOImpl 类：

 package com.shawn.mvcdemo.dao.impl;

 import java.sql.*;

 import com.shawn.mvcdemo.vo.User;
 import com.shawn.mvcdemo.dbc.*;
 import com.shawn.mvcdemo.dao.*;

 public class UserDAOImpl implements IUserDAO{
     private Connection conn = null;

     private PreparedStatement pstmt = null;

     public UserDAOImpl(Connection conn){
         this.conn = conn;
     }

     public boolean findLogin(User user) throws Exception{
         boolean flag = false;
         String sql = "select name from user where userid = ? and password = ?";
         this.pstmt = this.conn.prepareStatement(sql);
         this.pstmt.setString(1,user.getUserID());
         this.pstmt.setString(2,user.getPassword());
         ResultSet rs = this.pstmt.executeQuery();
         if(rs.next()){
             user.setName(rs.getString("name"));
             flag = true;
         }
         this.pstmt.close();
         return flag;
     }
 }

UserDAOProxy 类：

 package com.shawn.mvcdemo.dao.proxy;

 import java.sql.*;

 import com.shawn.mvcdemo.vo.User;
 import com.shawn.mvcdemo.dbc.*;
 import com.shawn.mvcdemo.dao.*;
 import com.shawn.mvcdemo.dao.impl.*;

 public class UserDAOProxy implements IUserDAO{
     private DatabaseConnection dbc = null;
     private IUserDAO dao = null;

     public UserDAOProxy(){
         try{
             this.dbc = new DatabaseConnection();
         } catch(Exception e){
             e.printStackTrace();
         }
         this.dao = new UserDAOImpl(this.dbc.getConnection());
     }

     public boolean findLogin(User user) throws Exception{
         boolean flag = false;
         try{
             flag = this.dao.findLogin(user);    //调用真实主题，完成操作
         } catch(Exception e){
             throw e;
         } finally{
             this.dbc.close();
         }
         return flag;
     }

 }

DAOFactory 类：

 package com.shawn.mvcdemo.factory;

 import com.shawn.mvcdemo.dao.*;
 import com.shawn.mvcdemo.dao.proxy.*;

 public class DAOFactory{
     public static IUserDAO getIUserDAOInstance(){
         return new UserDAOProxy();
     }
 }

LoginServlet 类：

 package com.shawn.mvcdemo.servlet;

 import java.io.*;
 import java.util.*;

 import javax.servlet.*;
 import javax.servlet.http.*;
 import com.shawn.mvcdemo.factory.*;
 import com.shawn.mvcdemo.vo.*;

 public class LoginServlet extends HttpServlet{

     public void doGet(HttpServletRequest req,HttpServletResponse resp)
         throws ServletException,IOException{
         String path = "login.jsp";
         String userID = req.getParameter("userID");
         String password = req.getParameter("password");
         List<String> info = new ArrayList<String>();//收集错误信息
         if(userID == null || "".equals(userID)){
             info.add("用户id不能为空！");
         }
         if(password == null || "".equals(password)){
             info.add("密码不能为空！");
         }
         if(info.size() == 0){//里面没有记录任何的错误
             User user = new User();
             user.setUserID(userID);
             user.setPassword(password);
             try{
                 if(new DAOFactory().getIUserDAOInstance().findLogin(user)){
                     info.add("用户登陆成功，欢迎" + user.getName() + "光临！");
                     System.out.println(1);
                 } else {
                     info.add("用户登录失败，错误的用户名和密码！");
                     System.out.println(2);
                 }
             }catch(Exception e){
                 e.printStackTrace();
             }
         }
         req.setAttribute("info",info);
         req.getRequestDispatcher(path).forward(req,resp);
     }

     public void doPost(HttpServletRequest req,HttpServletResponse resp)
         throws ServletException,IOException{
         this.doGet(req,resp);
     }

 }

login.jsp 页面：

 <%@ page contentType="text/html" pageEncoding="utf-8" import="java.util.*"%>
 <html>
     <head>
         <title>www.mldnjava.cn, MLDN高端Java培训</title>
         <%
             request.setCharacterEncoding("utf-8");
         %>
         <%
             List<String> info = (ArrayList<String>)request.getAttribute("info");
             String userID = request.getParameter("userID");
             String password = request.getParameter("password");
         %>
         <script>
             window.onload = function(){
                 var objForm = document.getElementById("form1");

                 objForm.onsubmit = function(){
                     if(!(/^\w{5,15}$/.test(this.userID.value))){
                         alert("用户ID必须是5~15位！");
                         this.userID.focus();
                         return false;
                     }

                     if(!(/^\w{5,15}$/.test(this.password.value))){
                         alert("密码必须是5~15位！");
                         this.password.focus();
                         return false;
                     }
                 }

             }

         </script>
     </head>

     <body>
         <form id="form1" action="login" method="post">
             用户ID：<input type="text" name="userID" value="<%= (userID == null) ? "" : userID %>" /><br>
             密&nbsp;&nbsp;码：<input type="password" name="password" value="<%= (password == null) ? "" : password %>" /><br>
             <input type="submit" value="登录" />
             <input type="reset" value="重置" />
         </form>
         <%
             if(info != null){
                 for(String str : info){
         %>
             <h3><%=str %></h3>
         <%
                 }
             }
         %>
     </body>
 </html>

web.xml 配置：

 <?xml version="1.0" encoding="ISO-8859-1"?>

 <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"> 

   <display-name>Hello World!</display-name>
   <welcome-file-list>
     <welcome-file>main.html</welcome-file>
   </welcome-file-list>

   <servlet>
     <servlet-name>login</servlet-name>
     <servlet-class>com.shawn.mvcdemo.servlet.LoginServlet</servlet-class>
   </servlet>

   <servlet-mapping>
     <servlet-name>login</servlet-name>
     <url-pattern>/mvclogin/login</url-pattern>
   </servlet-mapping>
 </web-app>