JAVA-WEB 过滤器Filter 用户自动登录

用户自动登录使用过滤器来实现。

1.当用户勾选自动登录时，在登录的servlet中将用户名密码记录到cookie。

2.新建filter在其中判断浏览器是否带着用户名和密码的cookie

3.验证cookie，将正确获得的用户实体存入到session

bean，service和dao就不传了都一样的代码

<%@ 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>
<meta charset="UTF-8">
<title>login</title>
</head>
<body>
	<h3>请登录:</h3>
	<h4><%=request.getAttribute("msg")!=null?request.getAttribute("msg"):""%></h4>
	<form action="${pageContext.request.contextPath }/loginServlet" method="post">
		<input type="text" name="username"  /><br/>
		<input type="password" name="password" /><br/>
 		是否自动登录:<input type="checkbox" name="autoLogin"><br/>
		<input type="submit" value="登录" /><br/>
	</from>
	
</body>
</html>

loginServlet

package web;
 
import java.io.IOException;
import java.net.URLEncoder;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import domain.User;
import service.UserService;
 
public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
 
	public LoginServlet() {
		super();
	}
 
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		//也可在filter中实现全局中文编码
		//tomcat8中已经处理了get方法中文处理
		request.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=utf-8");
		
		//获得是否自动登录的参数
		String autoLogin = request.getParameter("autoLogin");
		System.out.println("autoLogin:"+autoLogin);
		
		//获得request传来的参数
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		//封装到User类
		User user = new User();
		user.setUsername(username);
		user.setPassword(password);
		//查询用户是否存在
		UserService us = new UserService();
		User userFlag = null;
		try {
			userFlag = us.login(user);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		//response反馈
		if(userFlag != null) {
			
			//判断是否需要自动登录
			if(autoLogin!=null) {
				
				//转码中文用户名
				String username1 = URLEncoder.encode(userFlag.getUsername(), "UTF-8");
				//用cookie来保存用户名与密码,在过滤器中判断此cookie
				Cookie cusername = new Cookie("cusername", username1);
				Cookie cpassword = new Cookie("cpassword", userFlag.getPassword());
				cusername.setPath("/");
				cpassword.setPath("/");
				cusername.setMaxAge(60*60);//1小时
				cpassword.setMaxAge(60*60);//1小时
				response.addCookie(cusername);
				response.addCookie(cpassword);
			}
			
			System.out.println(userFlag);
			request.getSession().setAttribute("user", userFlag);
			request.getRequestDispatcher("/index.jsp").forward(request, response);
		}else {
			//错误信息一起返回到登录页面
			request.setAttribute("msg", "用户不存在或密码错误!");
			request.getRequestDispatcher("/request/login.jsp").forward(request, response);
			
		}
		
		
 
	}
 
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doGet(request, response);
	}
 
}

autoLoginFilter

package web;

import java.io.IOException;
import java.net.URL;
import java.net.URLDecoder;
import java.sql.SQLException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import domain.User;
import service.UserService;

public class AutoLoginFilter implements Filter{

	
	
	@Override
	public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain chain)
			throws IOException, ServletException {
		
		//转换参数类型
		HttpServletRequest request = (HttpServletRequest) arg0;
		HttpServletResponse response = (HttpServletResponse) arg1;
		
		//流程
		//1如果已登录，不进行自动登录
		//2如果浏览器没有自动登录cookie，不进行自动登录
		//3如果cookie不正确，步子动登录。
		//4如果没有自动登录且cookie信息正确，进行自动登录，将得到的用户存放到session中。
		
		//获得request域中的用户
		User loginUser = (User) request.getAttribute("user");
		//判断用户是否登录
		if(loginUser!=null) {
			//用户已登录，放行
			chain.doFilter(request, response);
			return;//结束程序
		}
		
		//获得request域中的cookie
		Cookie[] cookies = request.getCookies();
		Cookie cusername = null;
		Cookie cpassword = null;
		for (Cookie cookie : cookies) {
			if("cpassword".equals(cookie.getName())) {
				cpassword = cookie;
			}else if("cusername".equals(cookie.getName())) {
				cusername = cookie;
			}
		}
		
		//判断cookie是否为空
		if(cusername==null || cpassword==null) {
			chain.doFilter(request, response);
			return;//结束程序
		}
		
		
		//封装用户
		User user = new User();
		//这里处理一下servlet中URLEncode用户名的中文
		user.setUsername(URLDecoder.decode(cusername.getValue(), "UTF-8"));
		user.setPassword(cpassword.getValue());
		//调用service登录获得用户实体
		UserService us = new UserService();
		User login = null;
		try {
			login = us.login(user);
		} catch (SQLException e) {
			e.printStackTrace();
		}
		if(login!=null) {
			HttpSession session = request.getSession();
			session.setAttribute("user", login);
		}
		
		//放行
		chain.doFilter(request, response);
		
	}
	
	
	
	@Override
	public void destroy() {
		// TODO Auto-generated method stub
		
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {
		// TODO Auto-generated method stub
		
	}

}

JAVA-WEB 过滤器Filter 用户自动登录

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