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 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>