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我们。