MVC设计模式应用

  1. MVC登录程序清单                                                                                                                                                                                                                                                                                                                                                            
    1 User　　 JAVABean 用户登录操作类，跟数据库中表的信息对应
    2 DatabaseConnection JavaBean 负责数据库的连接和关闭操作
    3 IUserDAO JavaBean 定义登录操作的DAO接口
    4 UserDAOImpl JavaBean DAO接口的真实实现类，完成具体的登录验证
    5 UserDAOProxy JavaBean 定义代理操作，负责数据库的打开和关闭并且调用真实主体
    6 UserDAOFactory JavaBean 工厂类，取得DAO接口的实例
    7 LoginServlet Servlet 接收请求参数，进行参数验证，调用DAO完成具体的登录验证，并更具DAO的验证结果返回登录信息
    8 index.html jsp 提供用户输入
    9 login.jsp jsp 返回信息

User类

/**
 * 
 */
package org.lh.mvcdemo.vo;

/**
 * @author huanli2
 *
 */
public class User {
    private String userid;
    private String name;
    private String password;
    public String getUserid() {
        return userid;
    }
    public void setUserid(String userid) {
        this.userid = userid;
        
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    
}
  1. DateBaseConnectio类

　　

/**
 * 
 */
package org.lh.mvcdemo.dbc;

import java.sql.Connection;
import java.sql.DriverManager;

/**
 * @author huanli2
 *
 */
public class DatabaseConnection {
    private static final String DBDRIVER = "org.gjt.mm.mysql.Driver";
    private static final String DBURL = "jdbc:mysql://localhost:3306/mydb";
    private static final String DBUSER = "root";
    private static final String DBPASSWORD = "root";
    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;
            }
        }
    }
    
}
  1. IUserDAO类
/**
 * 
 */
package org.lh.mvcdemo.dao;

import org.lh.mvcdemo.vo.User;

/**
 * @author huanli2
 *
 */
public interface IUserDAO {
    public boolean findLogin(User user) throws Exception;
}
  1. UserDAOImpl
/**
 * 
 */
package org.lh.mvcdemo.dao.ipl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import org.lh.mvcdemo.dao.IUserDAO;
import org.lh.mvcdemo.vo.User;

/**
 * @author huanli2
 *
 */
public class UserDAOImpl implements IUserDAO{

    private Connection conn=null;
    private PreparedStatement pstmt = null;
    public UserDAOImpl (Connection conn){
        this.conn = conn;
    }
    /* (non-Javadoc)
     * @see org.lh.mvcdemo.dao.IUserDAO#findLogin(org.lh.mvcdemo.vo.User)
     */
    public boolean findLogin(User user) throws Exception {
        // TODO Auto-generated method stub
        boolean flag =false;
        try{
            String sql = "SELECT name FROM info 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(1));
                flag=true;
            }
        }catch(Exception e){
            throw e;
        }finally{
            if(this.pstmt!=null){
                try{
                    this.pstmt.close();
                }catch(Exception e){
                    throw e;
                }
            }
        }
        return flag;
    }

}

UserDAOProxy

/**
 * 
 */
package org.lh.mvcdemo.dao.proxy;

import org.lh.mvcdemo.dao.IUserDAO;
import org.lh.mvcdemo.dao.ipl.UserDAOImpl;
import org.lh.mvcdemo.dbc.DatabaseConnection;
import org.lh.mvcdemo.vo.User;

/**
 * @author huanli2
 *
 */
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());
    }

    /* (non-Javadoc)
     * @see org.lh.mvcdemo.dao.IUserDAO#findLogin(org.lh.mvcdemo.vo.User)
     */
    public boolean findLogin(User user) throws Exception {
        // TODO Auto-generated method stub
        boolean flag = false;
        try{
            flag = this.dao.findLogin(user);
        }catch(Exception e){
            throw e;
        }finally{
            this.dbc.close();
        }
        return flag;
    }
    
}

DAOFactory

/**
 * 
 */
package org.lh.mvcdemo.factory;

import org.lh.mvcdemo.dao.IUserDAO;
import org.lh.mvcdemo.dao.proxy.UserDAOProxy;

/**
 * @author huanli2
 *
 */
public class DAOFactory {
    public static IUserDAO getIUserDAOInstance(){
        return new UserDAOProxy();
    }
}

LoginServlet

package org.lh.mvcdemo.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.lh.mvcdemo.factory.DAOFactory;
import org.lh.mvcdemo.vo.User;

/**
 * Servlet implementation class LoginServlet
 */
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public LoginServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        String path = "login.jsp";
        String userid = request.getParameter("userid");
        String userpass = request.getParameter("userpass");
        List<String> info = new ArrayList<String>();
        if(userid==null||"".equals(userpass)){
            info.add("用户id不能为空！");
        }
        
        if(userpass==null||"".equals(userpass)){
            info.add("密码不能为空！");
        }
        if(info.size()==0){
            User user = new User();
            user.setPassword(userpass);
            user.setUserid(userid);
            try{
                if(DAOFactory.getIUserDAOInstance().findLogin(user)){
                    info.add("用户登录成功，欢迎"+user.getName()+"光临");
                }else{
                    info.add("用户登录失败，错误的用户名和密码!");
                }
            }catch(Exception e){
                e.printStackTrace();
            }
        }
        request.setAttribute("info", info);
        request.getRequestDispatcher(path).forward(request, response);
//        String userid = request.getParameter("userid");
//        String userpass = request.getParameter("userpass");
//        User user = new User();
//        user.setPassword(userpass);
//        user.setUserid(userid);
//        try{
//            if(DAOFactory.getIUserDAOInstance().findLogin(user)){
//                System.out.println("用户登录成功，欢迎"+user.getName()+"光临");
//            }else{
//                System.out.println("用户登录失败，错误的用户名和密码!");
//            }
//        }catch(Exception e){
//            e.printStackTrace();
//        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doGet(request, response);
    }

}

index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<form method="post" action="LoginServlet.do" >
用户Id: <input type="text" name="userid"><br>
密&nbsp;&nbsp;码<input type="password" name="userpass"><br>

<input type="submit" value="登录">
<input type="reset" value="重置">
</form>
</body>
</html>

login.jsp

<%@ page language="java" contentType="text/html; charset=GBK" import="java.util.*"
    pageEncoding="GBK"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<%
List<String> info = (List<String>)request.getAttribute("info");
if(info!=null){
    Iterator it = info.iterator();
    while(it.hasNext()){
        %> <h4><%=it.next() %></h4><% 
    }
}
%>
</body>
</html>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>m</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
      <servlet-name>login</servlet-name>
      <servlet-class>org.lh.mvcdemo.servlet.LoginServlet</servlet-class>
  </servlet>
  <servlet-mapping>
      <servlet-name>login</servlet-name>
      <url-pattern>/LoginServlet.do</url-pattern>
  </servlet-mapping>
</web-app>
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原文地址：https://www.cnblogs.com/yixianyixian/p/3501857.html