浏览器端存储技术简介
Cookie
Cookie 是指存储在用户本地终端上的数据，同时它是与具体的 Web 页面或者站点相关的。Cookie 数据会自动在 Web 浏览器和 Web 服务器之间传输，也就是说 HTTP 请求发送时，会把保存在该请求域名下的所有 Cookie 值发送给 Web 服务器，因此服务器端脚本是可以读、写存储在客户端的 Cookie 的操作。
LocalStorage
在 HTML5 中，新加入了一个 localStorage 特性，这个特性主要是用来作为本地存储来使用的，解决了 Cookie 存储空间不足的问题(Cookie 中每条 Cookie 的存储空间为 4k)，localStorage 中一般浏览器支持的是 5M 大小，这个在不同的浏览器中 localStorage 会有所不同。
SessionStorage
SessionStorage 与 LocalStorage 的唯一一点区别就是 LocalStorage 属于永久性存储，而 SessionStorage 属于当会话结束的时候，SessionStorage 中的键值对就会被清空。
UserData、GlobalStorage、Google Gear
这三种的使用都有一定的局限性，例如
- userData 是 IE 浏览器专属，它的容量可以达到 640K，这种方案可靠，不需要安装额外插件，只不过它仅在IE下有效
- globalStorage 适用于 Firefox 2+ 的浏览器，类似于 IE 的 userData
- google gear 是谷歌开发出的一种本地存储技术，需要安装 Gear 组件
Flash ShareObject（Flash Cookie）
这种方式能能解决上面提到的 Cookie 存储的两个弊端，而且能够跨浏览器，应该说是目前最好的本地存储方案。不过，需要在页面中插入一个 Flash，当浏览器没有安装 Flash 控件时就不能用了。所幸的是，没有安装 Flash 的用户极少。
附：CookieUtils
package com.funtl.leeshop.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‘记住我’
- 首先要把Cookie工具类复制进来
- 然后在登录成功时，判断是不是选中‘记住我’，如果是，把用户名和密码保存在Cookie中；否则，删除对应Cookie中的记录.
- 进入登录页面时，要获取Cookie，那么写在哪里呢？可以下载doGet()中，这就有问题了，一开始不会进到/login中，怎么办呢？可以从主页跳转到/login，在doGet()中获取Cookie中的用户信息，通过request传给login.jsp
login.jsp
<form action="/login" method="post">
<input type="email" name="email" class="form-control" placeholder="邮箱" value="${email}">
<input type="password" name="password" class="form-control" placeholder="密码" value="${password}">
<input type="checkbox" name="isRemember" ${isRemember!=null?"checked":""}> 记住我
<button type="submit" class="btn btn-primary btn-block btn-flat">登录</button>
</form>LoginController
@WebServlet(name = "LoginController", urlPatterns = "/login")
public class LoginController extends HttpServlet {
private static final String COOKIE_USER_INFO="userInfo";
protected void doGet(HttpServletRequest req, HttpServletResponse resq) throws ServletException, IOException {
String userInfo=CookieUtils.getCookieValue(req,COOKIE_USER_INFO);
if(!StringUtils.isBlank(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,resq);
}
protected void doPost(HttpServletRequest req, HttpServletResponse resq) throws ServletException, IOException{
// ApplicationContext context = new ClassPathXmlApplicationContext("spring-context.xml");
/* SpringContext context=new SpringContext();
UserService userService=(UserService) context.getBean("userService");*/
//UserService userService=new UserServiceImpl();
UserService userService=SpringContext.getBean("userService");
String email=req.getParameter("email");
String password = req.getParameter("password");
User user=userService.login(email,password);
//记住我
Boolean isRemember=req.getParameter("isRemember")==null?false:true;
//登录失败的处理
if(user==null){
req.setAttribute("message","用户名或密码错误");
req.getRequestDispatcher("/login.jsp").forward(req,resq);
}
//登录成功的处理
else{
//如果用户点击记住我
if(isRemember==true)
{
CookieUtils.setCookie(req,resq,COOKIE_USER_INFO,String.format("%s:%s",email,password));
}
else {
CookieUtils.deleteCookie(req,resq,COOKIE_USER_INFO);
}
resq.sendRedirect("/main.jsp");
}
}
}
meta自动跳转
<meta http-equiv="Refresh" content="0; url=/login"/>