java使用Filter实现自动登录的方法

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;   }}