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>