java使用Filter实现自动登录的方法

本文实例为大家分享了java实现自动登录的具体代码，供大家参考，具体内容如下

当你勾选（记住登录状态），用cookie保存用户名和密码。不勾选，cookie失效。
所有的页面都要经过autoLoginFilter.java 的过滤器，在这类中，必须要判断cookies不为null，获得所有的cookie，得到name为user的cookie，进行用户名和密码的验证，如果不为null，则将user存入session。
在LoginServlet.java中，获得username和password参数，进行dao验证，如果不为空，放入seesion中，进行页面跳转。
创建cookie对象。setpath("/"),表示本应用下的所有路径都能访问此cookie。
对于已经正确登录的用户，再次访问其他页面必定会再次经过autoLoginFilter，这时，判断当前session中的user是否为null，不为null，直接通过。
对于**login.jsp的有关页面，不需要经过autoLoginFilter。

package com.learning.web.servlet;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.Cookie;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.learning.domain.User;

import com.learning.service.UserService;

@WebServlet("/servlet/loginServlet")

public class LoginServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

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

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

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

UserService userService=new UserService();

User user = userService.findUser(username, password);

//user不为null，则登录成功

if (user!=null) {

//创建cookie来保存用户信息

Cookie cookie=new Cookie("user", user.getUsername()+"&"+user.getPassword());

cookie.setPath("/");

//autologin不为null，则记住了登录状态

if (autologin!=null) {

cookie.setMaxAge(1*60*60*24);//一天的有效时间

}

else {

cookie.setMaxAge(0);

}

response.addCookie(cookie);

request.getSession().setAttribute("user", user);

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

}else {

response.sendRedirect(request.getContextPath()+"/homeLogin.jsp");

}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doGet(request, response);

}

package com.learning.web.filter;

import java.io.IOException;

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.annotation.WebFilter;

import javax.servlet.annotation.WebInitParam;

import javax.servlet.http.Cookie;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import javax.servlet.http.HttpSession;

import javax.servlet.jsp.jstl.core.Config;

import com.learning.domain.User;

import com.learning.service.UserService;

@WebFilter(urlPatterns="/*",initParams={@WebInitParam(name="autologin",value="login"),@WebInitParam(name="",value="")})

public class AutoFilter implements Filter{

private FilterConfig filterConfig;

@Override

public void destroy() {

}

@Override

public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)

throws IOException, ServletException {

// 转换对象

HttpServletRequest httpServletRequest = (HttpServletRequest) request;

HttpServletResponse httpServletResponse = (HttpServletResponse) response;

// 获得访问的路径

String uri = httpServletRequest.getRequestURI();

String contextPath = httpServletRequest.getContextPath();

uri = uri.substring(contextPath.length() + 1);

// 获得初始化参数

String login = filterConfig.getInitParameter("autologin");

System.out.println("直接通行的路径："+login);

// 不包含"login"的路径就要进行过滤（xxxlogin.jsp 不需要自动登录）

if (!uri.contains(login)) {

HttpSession session = httpServletRequest.getSession();

User u = (User) session.getAttribute("user");

if (u != null) {

System.out.println("session不为null");

chain.doFilter(request, response);

} else {

// 处理业务逻辑

// 1.获得cookie 得到User的信息

String username = "";

String password = "";

UserService userService = new UserService();

Cookie[] cookies = httpServletRequest.getCookies();

for (int i = 0;cookies!=null&& i < cookies.length; i++) {

if ("user".equals(cookies[i].getName())) {

String string = cookies[i].getValue();

String[] values = string.split("&");

username = values[0];

password = values[1];

User user = userService.findUser(username, password);

// 不为空则放入session

if (user != null) {

System.out.println("自动登录了");

httpServletRequest.getSession().setAttribute("user", user);

}

// 2.放行

chain.doFilter(request, response);

}

@Override

public void init(FilterConfig filterConfig) throws ServletException {

this.filterConfig=filterConfig;

}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持快网idc。

java使用Filter实现自动登录的方法

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