java使用Filter实现自动登录的方法_Java教程

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;

									 }

									}