MVC之实例操作---MVC设计模式应用

MVC的第一个实例-----一个登陆：

首先我们需要一个VO类：

package com.keith.bean;

public class TUser implements java.io.Serializable {
	private static final long serialVersionUID = 1L;
	
	private Integer userid;
	private String userName;
	private String pwd;

	public TUser() {
	}

	public Integer getUserid() {
		return userid;
	}

	public void setUserid(Integer userid) {
		this.userid = userid;
	}

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}

	public String getPwd() {
		return pwd;
	}

	public void setPwd(String pwd) {
		this.pwd = pwd;
	}

}

 需要一个数据库工具类，DBConn：

package com.keith.util;

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

public class DBConn {
	private static final String DBDRIVER = "com.mysql.jdbc.Driver";
	private static final String DBURL = "jdbc:mysql://127.0.0.1:3306/login";
	private static final String DBUSER = "root";
	private static final String DBPWD = "kejianjun";
	private Connection conn = null;

	public DBConn() {
		try {
			Class.forName(DBDRIVER);
			conn = DriverManager.getConnection(DBURL, DBUSER, DBPWD);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		} catch (SQLException e) {
			e.printStackTrace();
		}

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

	public void setConn(Connection conn) {
		this.conn = conn;
	}

}

 然后从页面开始index.jsp（客户端验证一下）：

 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
	<script type="text/javascript">
		function validate(f){
			if (!(/^\w{4,15}$/.test(f.username.value))) {
				alert("用户名必须是4~16位！");
				f.username.focus();
				return false;
			}
			if (!(/^\w{4,15}$/.test(f.pwd.value))) {
				alert("密码必须是4~15位!");
				f.pwd.focus();
				return false;
			}
			return true;
		}
	</script>
  </head>
  
  <body>
  <%
  	List<String> info = (List<String>)request.getAttribute("info");
  	if(info != null){
  		Iterator<String> iter = info.iterator();
  		while(iter.hasNext()){
   %>
  	<h3><font color="red"><%=iter.next() %></font></h3> 
   <%}
   } %>
	<form action="login" method="post" onsubmit="return validate(this)" name="f">
		用户名：<input type="text" name="username"><br />
		密&nbsp;码:<input type="password" name="pwd"><br />
		<input type="submit" value="登陆">&nbsp;&nbsp;&nbsp;
		<input type="reset" value="取消">		
	</form>
  </body>
</html>

 然后通过发出的login请求在web.xml里找到想对应的servlet：

web.xml：

	<servlet>
		<servlet-name>login</servlet-name>
		<servlet-class>com.keith.servlet.LoginServlet</servlet-class>
	</servlet>  
	<servlet-mapping>
		<servlet-name>login</servlet-name>
		<url-pattern>/login</url-pattern>
	</servlet-mapping>
	
	<servlet>

 找到了LoginServlet：

package com.keith.servlet;

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

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

import com.keith.bean.TUser;
import com.keith.factory.DAOFactory;

/**
 * 定义Sevlet
 * 
 * @author T
 * 
 */
public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

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

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		String sucPath = "main.jsp";
		String loginEroPath = "index.jsp";
		String username = req.getParameter("username");
		String pwd = req.getParameter("pwd");
		List<String> info = new ArrayList<String>();
		if (username == null || "".equals(username)) {
			info.add("用户名不能为空!");
		}
		if (pwd == null || "".equals(pwd)) {
			info.add("密码不能为空！");
		}
		//用户名密码通过验证
		if (info.size() == 0) {
			//实例化VO
			TUser user = new TUser();
			//设置username
			user.setUserName(username);
			//设置pwd
			user.setPwd(pwd);
			if (DAOFactory.getIUserDAOInstance().findLogin(user)) {
				info.add("欢迎：" + user.getUserName());
				//保存信息，进行跳转
				req.setAttribute("info", info);
				req.getRequestDispatcher(sucPath).forward(req, resp);
			} else {
				info.add("用户信息错误！");
				req.setAttribute("info", info);
				req.getRequestDispatcher(loginEroPath).forward(req, resp);
			}
		}
	}

}

 通过DAO工厂找到UserDAO的实例：这是DAOFactory：

package com.keith.factory;

import com.keith.dao.IUserDAO;
import com.keith.dao.proxy.UserDAOProxy;

/**
 * 定义工厂类，取得DAO实例
 * @author T
 *
 */
public class DAOFactory {
	/**
	 * 取得DAO实例
	 * @return
	 */
	public static IUserDAO getIUserDAOInstance(){
		//返回代理实例
		return new UserDAOProxy();
	}
}

 返回代理实例，找到userDAO的代理类：

package com.keith.dao.proxy;

import com.keith.bean.TUser;
import com.keith.dao.IUserDAO;
import com.keith.dao.UserDAOImpl;
import com.keith.util.DBConn;

/**
 * DAO代理操作类
 * 
 * @author T
 * 
 */
public class UserDAOProxy implements IUserDAO {
	private DBConn dbc = null;
	private IUserDAO dao = null;

	public UserDAOProxy() {
		//实例化数据库连接
		this.dbc = new DBConn();
		this.dao = new UserDAOImpl(this.dbc.getConn());
	}

	/**
	 * 代理登陆方法
	 */
	public boolean findLogin(TUser user) {
		boolean flag = false;
		try {
			// 调用真实主题
			flag = this.dao.findLogin(user);
			this.dbc.close();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return flag;
	}

}

 找到UserDAOImpl的并执行它的findLogin()方法：

package com.keith.dao;

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

import com.keith.bean.TUser;

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

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

	/**
	 * 登陆
	 * 
	 * @throws SQLException
	 */
	public boolean findLogin(TUser user) {
		boolean flag = false;
		try {
			String sql = "SELECT username,pwd FROM tuser WHERE username=? and pwd=?";
			this.pstm = this.conn.prepareStatement(sql);
			this.pstm.setString(1, user.getUserName());
			this.pstm.setString(2, user.getPwd());
			ResultSet rs = this.pstm.executeQuery();
			if (rs.next()) {
				user.setUserName(rs.getString(1));
				flag = true;
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			try {
				if (this.pstm != null) {
					this.pstm.close();
				}
			} catch (SQLException e2) {
				e2.printStackTrace();
			}
		}
		return flag;
	}

}

 实现了IUserDAO接口：

package com.keith.dao;

import java.sql.SQLException;

import com.keith.bean.TUser;

/**
 * userDao接口
 * 
 * @author T
 * 
 */
public interface IUserDAO {
	/**
	 * 用户登录验证
	 * 
	 * @param user
	 * @return
	 */
	public boolean findLogin(TUser user);
}

 以上就是一个MVC的简单实例；