Cookie实现记住密码

百科定义

类型为小型文本文件，是某些网站为了辨别用户身份，进行Session跟踪而存储在用户本地终端上的数据（通常经过加密），由用户客户端计算机暂时或永久保存的信息。
组成

大小不超过 4KB
- Name/Value
- Expires
- Path
- Domain
- Secure
- HTTPOnly

package com.hhhqqq.my.shop.commons.utils;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;

/**
 * Cookie 工具类
 * <p>Title: CookieUtils</p>
 * <p>Description: </p>
 *
 * @author Lusifer
 * @version 1.0.0
 * @date 2017/12/10 22:00
 */
public final class CookieUtils {

    /**
     * 得到Cookie的值, 不编码
     *
     * @param request
     * @param cookieName
     * @return
     */
    public static String getCookieValue(HttpServletRequest request, String cookieName) {
        return getCookieValue(request, cookieName, false);
    }

    /**
     * 得到Cookie的值
     *
     * @param request
     * @param cookieName
     * @return
     */
    public static String getCookieValue(HttpServletRequest request, String cookieName, boolean isDecoder) {
        Cookie[] cookieList = request.getCookies();
        if (cookieList == null || cookieName == null) {
            return null;
        }
        String retValue = null;
        try {
            for (int i = 0; i < cookieList.length; i++) {
                if (cookieList[i].getName().equals(cookieName)) {
                    if (isDecoder) {
                        retValue = URLDecoder.decode(cookieList[i].getValue(), "UTF-8");
                    } else {
                        retValue = cookieList[i].getValue();
                    }
                    break;
                }
            }
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return retValue;
    }

    /**
     * 得到Cookie的值,
     *
     * @param request
     * @param cookieName
     * @return
     */
    public static String getCookieValue(HttpServletRequest request, String cookieName, String encodeString) {
        Cookie[] cookieList = request.getCookies();
        if (cookieList == null || cookieName == null) {
            return null;
        }
        String retValue = null;
        try {
            for (int i = 0; i < cookieList.length; i++) {
                if (cookieList[i].getName().equals(cookieName)) {
                    retValue = URLDecoder.decode(cookieList[i].getValue(), encodeString);
                    break;
                }
            }
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        return retValue;
    }

    /**
     * 设置Cookie的值 不设置生效时间默认浏览器关闭即失效,也不编码
     */
    public static void setCookie(HttpServletRequest request, HttpServletResponse response, String cookieName,
                                 String cookieValue) {
        setCookie(request, response, cookieName, cookieValue, -1);
    }

    /**
     * 设置Cookie的值 在指定时间内生效,但不编码
     */
    public static void setCookie(HttpServletRequest request, HttpServletResponse response, String cookieName,
                                 String cookieValue, int cookieMaxage) {
        setCookie(request, response, cookieName, cookieValue, cookieMaxage, false);
    }

    /**
     * 设置Cookie的值 不设置生效时间,但编码
     */
    public static void setCookie(HttpServletRequest request, HttpServletResponse response, String cookieName,
                                 String cookieValue, boolean isEncode) {
        setCookie(request, response, cookieName, cookieValue, -1, isEncode);
    }

    /**
     * 设置Cookie的值 在指定时间内生效, 编码参数
     */
    public static void setCookie(HttpServletRequest request, HttpServletResponse response, String cookieName,
                                 String cookieValue, int cookieMaxage, boolean isEncode) {
        doSetCookie(request, response, cookieName, cookieValue, cookieMaxage, isEncode);
    }

    /**
     * 设置Cookie的值 在指定时间内生效, 编码参数(指定编码)
     */
    public static void setCookie(HttpServletRequest request, HttpServletResponse response, String cookieName,
                                 String cookieValue, int cookieMaxage, String encodeString) {
        doSetCookie(request, response, cookieName, cookieValue, cookieMaxage, encodeString);
    }

    /**
     * 删除Cookie带cookie域名
     */
    public static void deleteCookie(HttpServletRequest request, HttpServletResponse response,
                                    String cookieName) {
        doSetCookie(request, response, cookieName, "", -1, false);
    }

    /**
     * 设置Cookie的值，并使其在指定时间内生效
     *
     * @param cookieMaxage cookie生效的最大秒数
     */
    private static final void doSetCookie(HttpServletRequest request, HttpServletResponse response,
                                          String cookieName, String cookieValue, int cookieMaxage, boolean isEncode) {
        try {
            if (cookieValue == null) {
                cookieValue = "";
            } else if (isEncode) {
                cookieValue = URLEncoder.encode(cookieValue, "utf-8");
            }
            Cookie cookie = new Cookie(cookieName, cookieValue);
            if (cookieMaxage > 0)
                cookie.setMaxAge(cookieMaxage);
            if (null != request) {// 设置域名的cookie
                String domainName = getDomainName(request);
//                System.out.println(domainName);
                if (!"localhost".equals(domainName)) {
                    cookie.setDomain(domainName);
                }
            }
            cookie.setPath("/");
            response.addCookie(cookie);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 设置Cookie的值，并使其在指定时间内生效
     *
     * @param cookieMaxage cookie生效的最大秒数
     */
    private static final void doSetCookie(HttpServletRequest request, HttpServletResponse response,
                                          String cookieName, String cookieValue, int cookieMaxage, String encodeString) {
        try {
            if (cookieValue == null) {
                cookieValue = "";
            } else {
                cookieValue = URLEncoder.encode(cookieValue, encodeString);
            }
            Cookie cookie = new Cookie(cookieName, cookieValue);
            if (cookieMaxage > 0)
                cookie.setMaxAge(cookieMaxage);
            if (null != request) {// 设置域名的cookie
                String domainName = getDomainName(request);
//                System.out.println(domainName);
                if (!"localhost".equals(domainName)) {
                    cookie.setDomain(domainName);
                }
            }
            cookie.setPath("/");
            response.addCookie(cookie);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 得到cookie的域名
     */
    private static final String getDomainName(HttpServletRequest request) {
        String domainName = null;

        String serverName = request.getRequestURL().toString();
        if (serverName == null || serverName.equals("")) {
            domainName = "";
        } else {
            serverName = serverName.toLowerCase();
            serverName = serverName.substring(7);
            final int end = serverName.indexOf("/");
            serverName = serverName.substring(0, end);
            final String[] domains = serverName.split("\.");
            int len = domains.length;
            if (len > 3) {
                // www.xxx.com.cn
                domainName = "." + domains[len - 3] + "." + domains[len - 2] + "." + domains[len - 1];
            } else if (len <= 3 && len > 1) {
                // xxx.com or xxx.cn
                domainName = "." + domains[len - 2] + "." + domains[len - 1];
            } else {
                domainName = serverName;
            }
        }

        if (domainName != null && domainName.indexOf(":") > 0) {
            String[] ary = domainName.split("\:");
            domainName = ary[0];
        }
        return domainName;
    }

}

实现

LoginController - 设置Cookie

判断是否选择记住密码，设置Cookie

index.jsp

<div class="col-xs-8">
    <div class="checkbox icheck">
        <label>
            <input name="isRemember" type="checkbox" ${isRemember == true ? "checked" : ""}> 记住密码
        </label>
    </div>
</div>

doPost

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    String email = req.getParameter("email");
    String password = req.getParameter("password");
    boolean isRemember = req.getParameter("isRemember") == null ? false : true;

    SpringContext springContext = new SpringContext();
    UserService userService = (UserService) springContext.getBean("userService");
    User user = userService.login(email, password);

    // 不记住密码
    if (!isRemember) {
        CookieUtils.deleteCookie(req, resp, COOKIE_NAME_USER_INFO);
    }

    if (user != null) {
        // 登录成功 且 记住密码
        if (isRemember) {
            CookieUtils.setCookie(req, resp, COOKIE_NAME_USER_INFO, String.format("%s:%s", email, password), 7*24*60*60);
        }

        resp.sendRedirect("/main.jsp");
    }
    else {
        req.setAttribute("loginErrorMessage","用户名或密码错误");
        req.getRequestDispatcher("/index.jsp").forward(req,resp);
    }
}

LoginController - 获取Cookie

点击登录能够将信息保存到Cookie了，那每次打开的时候如何拿到？

在 doGet 里通过 getCookieValue 获得Cookie
默认打开index.jsp ，没有经过doGet方法，怎么转到login？

也就是每次打开的时候先打开index.jsp,地址是：http://localhost:8080 ，怎么才能一打开就是：http://localhost:8080/login
1. 新建一个login.jsp
2. 将index.jsp的内容拷到login.jsp
3. 在index.jsp使用 meta跳转
```
<meta http-equiv="Refresh" content="0; url=/login" />
```
doGet里获取Cookie，并跳转到login.jsp

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    String userInfo = CookieUtils.getCookieValue(req, COOKIE_NAME_USER_INFO);

    if (StringUtils.isNoneBlank(userInfo)) {
        String[] userInfoArray = userInfo.split(":");
        String email = userInfoArray[0];
        String password = userInfoArray[1];

        req.setAttribute("email", email);
        req.setAttribute("password", password);
        req.setAttribute("isRemember", true);
    }

    req.getRequestDispatcher("/login.jsp").forward(req, resp);
}

login.jsp 设置value

<div class="form-group has-feedback">
    <input name="email" type="email" class="form-control" placeholder="邮箱" value="${email}">
    <span class="glyphicon glyphicon-envelope form-control-feedback"></span>
</div>
<div class="form-group has-feedback">
    <input name="password" type="password" class="form-control" placeholder="密码" value="${password}">
    <span class="glyphicon glyphicon-lock form-control-feedback"></span>
</div>
<div class="row">
    <div class="col-xs-8">
        <div class="checkbox icheck">
            <label>
                <input name="isRemember" type="checkbox" ${isRemember == true ? "checked" : ""}> 记住密码
            </label>
        </div>
    </div>
    <!-- /.col -->
    <div class="col-xs-4">
        <button type="submit" class="btn btn-primary btn-block btn-flat">登录</button>
    </div>
    <!-- /.col -->
</div>

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原文地址：https://www.cnblogs.com/hujh/p/13792113.html

Cookie实现记住密码

Cookie 认识

Cookie 工具类

实现

LoginController - 设置Cookie

LoginController - 获取Cookie

login.jsp 设置value