Filter(四)常见应用4---自动登录

很多网站目前有这样一种功能，在客户首次登录页面时，会提醒客户是否在一段时间内自动登录，设为自动登录，待客户下次登录改页面时，不要求用户再次输入用户名和密码，而是直接登录到，这样方便了用户访问此网站。在学完Filter后，可以利用Filter加cookie来完成全网站自动登录功能。

数据层需要定义一个用户对象，其中包括用户名和密码

public class User {private String name;private String password;public User(){}public User(String name, String password){super();this.name = name;this.password = password;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}}

对应的数据增加一张User表，如下：

create table user( id varchar(40) primary key, name varchar(20) unique not null, password varchar(20) );

dao层，提供了一个add方法和一个find方法，分别如下：

public interface UserDao {void add(User user) throws SQLException; //用户注册时，向数据库中添加一条记录User find(String name) throws SQLException;//用户登录时，从数据库查找是否存在这条记录}

dao实现，首先这里使用的apache的dbutils工具包来操作数据库，数据库连接池使用c3p0来创建。dao实现如下：这里使用UUID来生成一个随机ID；

public class UserDaoImpl implements UserDao {public void add(User user) throws SQLException{QueryRunner qr = new QueryRunner();String sql = "insert into user(id, name, password) values(?,?,?)";Object[] params = {JdbcDbutils.makeUUID(), user.getName(), user.getPassword()};qr.update(JdbcDbutils.getConnection(), sql, params);}public User find(String name) throws SQLException{QueryRunner qr = new QueryRunner();String sql = "select * from user where name=?";Object[] params = {name};return (User)qr.query(JdbcDbutils.getConnection(), sql, new BeanHandler(User.class), params);}}

到这里数据层已经准备好了，service层主要涉及到注册和登录，登录分为自动登录和手动登录(自动登录失效后).当用户手动时，要是用户选择了下次自动登录，则在登录时，将会生成一个cookie文件，将用户的姓名和密码存入到cookie中，带下次用户访问此网站时，将自动从cookie中获取用户名和密码，实现自动登录。当然这里存入到cookie中密码，原则上是要进行加密的，示例中就不进行加密了，存的是明文。下面是自动登录工具类：

package cn.itcast.utils;import java.io.IOException;import javax.servlet.FilterChain;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import cn.itcast.domain.User;import cn.itcast.exceptions.UserOperException;import cn.itcast.service.UserService;import cn.itcast.service.impl.UserServiceImpl;public class AutoLoginUtils {public static void saveLoginInfoToCookie(User user, HttpServletRequest request, HttpServletResponse response) throws UserOperException{UserService service = new UserServiceImpl();User user1 = service.find(user.getName());if(user1.getPassword().equals(user.getPassword())){Cookie cookie = new Cookie("autologin", user.getName()+"#"+user.getPassword());cookie.setMaxAge(3600); //必须设置值，否则此cookie只会存在浏览器内存中，浏览器关闭，此cookie将会删除cookie.setPath("/");   //设置在根目录下，这样在此web应用下，都可以访问response.addCookie(cookie);request.getSession().setAttribute("user", user); //将user存到到session中}}public static void readCookieAndLogin(HttpServletRequest request, HttpServletResponse response,FilterChain chain) throws IOException, ServletException{User user = (User) request.getSession().getAttribute("user");if(user!=null){chain.doFilter(request, response);return;}Cookie[] cookies = request.getCookies();String cookieValue = null;for (int i=0; cookies!=null && i<cookies.length; i++) {Cookie ck = cookies[i];if (ck.getName().equals("autologin")) {cookieValue = ck.getValue();break;}}if(cookieValue==null){chain.doFilter(request, response);return;}String name = cookieValue.substring(0, cookieValue.lastIndexOf("*"));String password = cookieValue.substring(cookieValue.lastIndexOf("#") + 1);UserService service = new UserServiceImpl();try {user = service.find(name);if (user!=null && user.getPassword().equals(password)) {request.getSession().setAttribute("user", user);} else {request.setAttribute("message", "您还未登录，请先登录");}} catch (UserOperException e) {// TODO Auto-generated catch blocke.printStackTrace();}chain.doFilter(request, response);}}

过滤器

public class AutoLoginFilter implements Filter {@Overridepublic void destroy() {// TODO Auto-generated method stub}@Overridepublic void doFilter(ServletRequest req, ServletResponse resp,FilterChain chain) throws IOException, ServletException {// TODO Auto-generated method stubHttpServletRequest request = (HttpServletRequest) req;HttpServletResponse response = (HttpServletResponse) resp;AutoLoginUtils.readCookieAndLogin(request, response, chain);}@Overridepublic void init(FilterConfig config) throws ServletException {// TODO Auto-generated method stub}}

登录servlet

public class LoginServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {String name = request.getParameter("name");String password = request.getParameter("logPwd");String checkCode = request.getParameter("checkcode");String imageCode = (String) request.getSession().getAttribute("checkcode");String autoLogin = request.getParameter("autologin");if (!checkCode.equals(imageCode)){request.setAttribute("message", "校验码输入错误<meta http-equiv='refresh' content='3,url=/AutoLogin/index.jsp'");request.getRequestDispatcher("/jsp/message.jsp").forward(request, response);return;}try {UserService service = new UserServiceImpl();User user = service.find(name);if(user!=null && user.getPassword().equals(password)){/*if(autoLogin.equals("on")){Cookie cookie = new Cookie("autologin", name+"*"+password);cookie.setMaxAge(3600);cookie.setPath("/");response.addCookie(cookie);}*/AutoLoginUtils.saveLoginInfoToCookie(user, request, response);request.getSession().setAttribute("user", user);request.getRequestDispatcher("/index.jsp").forward(request, response);return;}else{request.setAttribute("message", "用户名或密码输入错误<meta http-equiv='refresh' content='3,url=/AutoLogin/index.jsp'");request.getRequestDispatcher("/jsp/message.jsp").forward(request, response);return;}} catch (UserOperException e) {// TODO Auto-generated catch blocke.printStackTrace();request.setAttribute("message", "登录失败<meta http-equiv='refresh' content='3,url=/AutoLogin/index.jsp'");request.getRequestDispatcher("/jsp/message.jsp").forward(request, response);return;}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}