package www.test.web.servlet;

import java.io.IOException;
import java.net.URLEncoder;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import www.test.domain.User;
import www.test.service.LoginService;

public class LoginServlet extends HttpServlet {

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

        // 解决乱码问题
        request.setCharacterEncoding("UTF-8");
        HttpSession session = request.getSession();

        // 获得页面输入的验证
        String checkCode_client = request.getParameter("checkCode");
        // 获得生成图片的文字的验证码
        String checkCode_session = (String) request.getSession().getAttribute("checkcode_session");
        // 比对页面的和生成图片的文字的验证码是否一致
        if (!checkCode_session.equals(checkCode_client)) {
            request.setAttribute("loginInfo", "您的验证码不正确");
            request.getRequestDispatcher("/login.jsp").forward(request, response);
            return;
        }
        // 获取用户输入的数据
        String username = request.getParameter("username"); //中文名张三
        String password = request.getParameter("password");

        LoginService service = new LoginService();
        User user = null;
        try {
            user = service.login(username, password);
        } catch (SQLException e) {

            e.printStackTrace();
        }

        if (user != null) {
            // 登录成功
            // 判断用户是否勾选自动登录
            String autoLogin = request.getParameter("autoLogin");
            if (autoLogin != null) {
                
                //对中文张三进行编码
                String username_code = URLEncoder.encode(username, "UTF-8");// %AE4%kfj
                
                
                Cookie cookie_username = new Cookie("cookie_username", username_code);
                Cookie cookie_password = new Cookie("cookie_password", password);
                // 设置 cookie 的持久化时间
                cookie_username.setMaxAge(60 * 60);
                cookie_password.setMaxAge(60 * 60);
                // 设置 cookie 的携带路径
                cookie_username.setPath(request.getContextPath());
                cookie_password.setPath(request.getContextPath());
                // 发送 cookie
                response.addCookie(cookie_username);
                response.addCookie(cookie_password);
            }
            
            //将登录的用户的 user 对象存到 session 中
            session.setAttribute("user", user);
            //重定向到首页
            response.sendRedirect(request.getContextPath());
        } else {
            request.setAttribute("loginInfo", "密码或者用户名不正确");
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

package www.test.web.filter;

import java.io.IOException;
import java.net.URLDecoder;
import java.sql.SQLException;

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.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import www.test.domain.User;
import www.test.service.LoginService;

public class AutoLoginFilter implements Filter {

    public AutoLoginFilter() {
        super();
    }

    private FilterConfig filterConfig;

    public void init(FilterConfig filterConfig) throws ServletException {

        this.filterConfig = filterConfig;

    }

    public void doFilter(ServletRequest req, ServletResponse res, FilterChain filterChain)
            throws IOException, ServletException {

        HttpServletRequest request = (HttpServletRequest) req;

        HttpServletResponse response = (HttpServletResponse) res;

        HttpSession session = request.getSession();

        // 获得 cookie 中用户名和密码 进行登录的操作
        // 定义 cookie_username
        String cookie_username = null;
        // 定义 cookie_password
        String cookie_password = null;
        // 获得 cookie
        Cookie[] cookies = request.getCookies();
        if (cookies != null) {
            for (Cookie cookie : cookies) {// 获得名字是 cookie_username 和
                                            // cookie_password
                if ("cookie_username".equals(cookie.getName())) {
                    cookie_username = cookie.getValue();
                    //恢复中文用户名
                    cookie_username = URLDecoder.decode(cookie_username, "UTF-8");
                }
                if ("cookie_password".equals(cookie.getName())) {
                    cookie_password = cookie.getValue();
                }
            }
        }
        // 判断 username 和 password 是否是 null
        if (cookie_username != null && cookie_password != null) {
            // 登录的代码
            LoginService service = new LoginService();
            
            User user = null;
            try {
                user = service.login(cookie_username, cookie_password);
            } catch (SQLException e) {
                e.printStackTrace();
            }
            // 将登录的用户的 user 对象存到 session 中
            session.setAttribute("user", user);
        }

        filterChain.doFilter(req, res);
        // 这里放到达目的地(离开)的处理代码
        
        //放行
        filterChain.doFilter(request, response);
    }

    public void destroy() {

    }
}