jsp中的一个简单的登录的一个例子

import java.io.IOException;

import javax.servlet.Servlet;

import javax.servlet.ServletConfig;

import javax.servlet.ServletException;

import javax.servlet.ServletRequest;

import javax.servlet.ServletResponse;

import javax.servlet.http.HttpServletResponse;

import com.dao.UserDAO;

//这是控制层

public class UserServlet implements Servlet {

public void destroy() {

// TODO Auto-generated method stub

}

public ServletConfig getServletConfig() {

// TODO Auto-generated method stub

return null;

}

public String getServletInfo() {

// TODO Auto-generated method stub

return null;

}

public void init(ServletConfig arg0) throws ServletException {

// TODO Auto-generated method stub

}

/*

* 1.接收请求参数 2.调用业务(dao) 3.视图分发

*/

public void service(ServletRequest request, ServletResponse response)

throws ServletException, IOException {

// 处理中文,只能处理post提交

request.setCharacterEncoding("utf-8");

// 1.接收参数,双引号的username就是login.jsp中的用户名的<input type=text name=username

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

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

// 处理get

// username = new String(username.getBytes("iso8859-1"),"utf-8");

// System.out.println(username);

// System.out.println(password);

// 2.调用业务(dao)

UserDAO userDAO = new UserDAO();

boolean f = userDAO.checkLogin(username, password);

// 3.视图分发

if (f) {

//转发

request.getRequestDispatcher("/yes.jsp").forward(request, response);

} else {

//重定向

HttpServletResponse res = (HttpServletResponse)response;

res.sendRedirect("login.jsp");

}

}

}

import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

//这是模型层

public class UserDAO {

// 登陆

//1' or '1'='1

public boolean checkLogin(String username, String password) {

String sql = "select * from users where username=? and password=?";

try {

//加载驱动

Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");

//建立连接

Connection con = DriverManager.getConnection(

"jdbc:sqlserver://127.0.0.1:1433;DatabaseName=test", "sa",

"sasa");

PreparedStatement ps = con.prepareStatement(sql);

ps.setObject(1, username);

ps.setObject(2, password);

ResultSet rs = ps.executeQuery();

if (rs.next()) {

return true;

}

} catch (ClassNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

return false;

}

}

//这是web.xml的配置

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="2.4"

xmlns="http://java.sun.com/xml/ns/j2ee"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee

http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<welcome-file-list>

<welcome-file>index.jsp</welcome-file>

</welcome-file-list>

<!-- servlet注册 -->

<servlet>

<servlet-name>FirstServlet</servlet-name>

<servlet-class>com.servlets.UserServlet</servlet-class>

</servlet>

<!-- servlet映射 -->

<servlet-mapping>

<servlet-name>FirstServlet</servlet-name>

<url-pattern>/go</url-pattern>

</servlet-mapping>

</web-app>

//这是是视图层

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

<form action='go' method="post">

用户名：<input type=text name=username> <br>

密码:<input type=password name=password> <br>

<input type=submit value="登陆">

</form>