java实现简单的登陆

用java做简单的登陆都做的恶心了，以前的学校就是，但有网友问起，还是做了一个。

登陆页面实现成功登陆案例

实现目标：登陆成功后进入成功页面，失败时进入失败页面（采用mvc模式，将控制与页面分离）

效果展示：

输入正确的用户名密码时：

用户名和密码错误时：

数据库表结构：

Jsp页面，主要由登陆页面（index.jsp）、操作页面（check.jsp）、成功页面（success。jsp）和失败页面（error.jsp）组成。

Index.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"

pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Insert title here</title>

</head>

function checkout(){

var user = document.getElementById("user").Value;

var password = document.getElementById("password").Value;

if(user==""){

alert("请输入用户名！！！");

return false;

}

else if(password==""){

alert("请输入密码！！");

return false;

}else {

return true;

}

</script>

<body>

用户名：<input type="text" name="user" id="user"><br>

密码： <input type="password" name="password" id="password">

</form>

</body>

</html>

Check.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<head>

<title>Insert title here</title>

</head>

String user = request.getParameter("user");

String password = request.getParameter("password");

boolean flag = false;

if(user !=null && password !=null){

Chc c = new Chc();

flag =c.isExist(user,password);

}

if(flag==true){

RequestDispatcher dispatcher = request.getRequestDispatcher("success.jsp");

dispatcher.forward(request,response);

}else {

RequestDispatcher dispatcher = request.getRequestDispatcher("error.jsp");

dispatcher.forward(request,response);

}

<body>

</body>

<%@page import="com.dao.Chc"%></html>

Success.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Insert title here</title>

</head>

<body>

<h1>欢迎您的登陆！</h1>

</body>

</html>

Error.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Insert title here</title>

</head>

<body>

<h1>用户名和密码错误，请重新输入</h1>

</body>

</html>

Dao

package com.dao;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import com.util.Conection;

public class Chc {

Connection con = Conection.getConnection();

public boolean isExist(String user,String password){

boolean flag = false;

String sql = "select * from t_user where user=? and password=?";

try {

PreparedStatement ps = con.prepareStatement(sql);

ps.setString(1, user);

ps.setString(2, password);

ResultSet rs = ps.executeQuery();

if(rs.next()){

flag = true;

}

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return flag;

}

Util jdbc 连接mysql数据库

package com.util;

import java.sql.Connection;

import java.sql.DriverManager;

public class Conection {

public static Connection getConnection(){

String dbClassName="com.mysql.jdbc.Driver";

String dbUrl ="jdbc:mysql://localhost:3306/rubish?useUnicode=true&characterEncoding=utf8";

String dbUser ="root";

String dbPwd ="fly";

Connection con = null;

try{

Class.forName(dbClassName);

//getConnection(String url, String user, String password) ��ͼ��ݿ� URL ��ӡ�

con = DriverManager.getConnection(dbUrl, dbUser, dbPwd);

}

catch (Exception e) {

e.printStackTrace();

}

return con;

}