MVC实例应用模式
1.可用性：
比如异常处理
2.可修改性：
比如用接口实现
3.性能战术：
4.易用性战术：
分层实现
5.可测试性战术：
实现对其接口进行测试，并不需要对其实现方法进行
6.安全性战术：
对用户的密码进行MD5加密
MVC设计实现及其具体应用
实体类：
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 码:<input type="password" name="pwd"><br />
<input type="submit" value="登陆">
<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：
<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);
}
MVC设计模式在具体网站中的应用
对于百度的首页来说
给用户呈现的就是V,每当用户输入不同的内容，数据层就会处理呈现出不同的页面