可以先看看別的大佬寫的瞭解下cookie,具體我也不知道怎麼講哈哈哈哈或或或!
然後自己寫了個記住賬號密碼功能,附帶查看cookie的值,刪除cookie的功能!
首先,在index.jsp中寫好登錄界面,並添加獲取cookie中賬號和密碼信息並放進input中。以下是代碼:
<%--
Created by IntelliJ IDEA.
User: HSW
Date: 2018/4/20
Time: 11:09
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%
Cookie[] cookies = request.getCookies();
String admin = "";
String password = "";
if(cookies != null)
for(Cookie cookie : cookies){
if(cookie.getName().equals("admin"))
admin = cookie.getValue();
else if(cookie.getName().equals("pwd"))
password = cookie.getValue();
}
%>
<html>
<head>
<title>Cookie Login</title>
<style>
div{
width: 800px;
height: 800px;
margin: 200px auto;
}
h1{
width: 400px;
height: auto;
margin: 0 auto;
}
table{
width: 400px;
height: auto;
margin: 0 auto;
}
</style>
</head>
<body>
<form action="${pageContext.request.contextPath}/setcookie" method="post">
<div>
<h1>登錄</h1>
<table>
<tr><td><label for="admin">用戶名:</label></td>
<td><input type="text" id="admin" placeholder="請輸入你的用戶名" name="admin" value="<%=admin%>"></td></tr>
<tr><td><label for="pwd">密碼:</label></td>
<td><input type="password" id="pwd" name="pwd" value="<%=password %>"></td></tr>
<tr><td><input type="submit" value="登錄"></td><td><input type="reset" value="重置"></td></tr>
</table>
</div>
</form>
</body>
</html>
將上面java代碼字符串信息放進input框裏面的方法就是像上面的這句一樣:value="<%=password %>">
每次訪問這個頁面時就先執行上面的java程序,第一次時沒有賬號信息,getCookies返回空,所以就不會自動填補input!
然後新建一個Servlet相當於下面的A服務器,將登錄信息放進Cookie!
代碼如下:
package cn.jxufe;
import javax.servlet.http.Cookie;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.URLEncoder;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
public class CookieSer extends javax.servlet.http.HttpServlet {
protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
response.setContentType("text/html; charset=utf-8");
String admin = request.getParameter("admin");
String password = request.getParameter("pwd");
DateFormat format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
String datestr = format.format(new Date());
Cookie cookie = new Cookie("admin", admin);
Cookie cookie2 = new Cookie("pwd", password);
Cookie cookie3 = new Cookie("date", URLEncoder.encode(datestr,"utf-8"));
response.addCookie(cookie);
response.addCookie(cookie2);
response.addCookie(cookie3);
PrintWriter out = response.getWriter();
out.write("<html>");
out.write("<head>");
out.write("<title>WebCookie</title>");
out.write("</head>");
out.write("<body>");
out.write("賬號密碼已被添加進cookie");
out.write("<a href=\"/look\">查看登錄信息</a>");
out.write("</body>");
out.write("</html>");
}
protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response) throws javax.servlet.ServletException, IOException {
doPost(request,response);
}
}
效果:
可以看到將賬號、密碼、最近一次登錄時間都寫進了cookie。
這時返回登錄界面刷新下看看:
賬號密碼都被保存!
然後在上面的Servlet加了一個<a>跳轉至另一個查看cookie信息的Servlet,名爲LookCookieContent(url-pattern是/look), 代碼:
package cn.jxufe;
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 java.io.IOException;
import java.io.PrintWriter;
import java.net.URLDecoder;
import java.net.URLEncoder;
public class LookCookieContent extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
Cookie[] cookies = request.getCookies();
String admin = "暫無該項信息";
String password = "暫無該項信息";
String date = "暫無該項信息";
if(cookies != null)
for(Cookie cookie : cookies){
if(cookie.getName().equals("admin"))
admin = cookie.getValue();
else if(cookie.getName().equals("pwd"))
password = cookie.getValue();
else if(cookie.getName().equals("date"))
date = URLDecoder.decode(cookie.getValue(), "utf-8");
}
PrintWriter out = response.getWriter();
out.write("<html>\n" +
"<head>\n" +
" <title>Cookie Login</title>\n" +
" <style>\n" +
" div{\n" +
" width: 800px;\n" +
" height: 800px;\n" +
" margin: 200px auto;\n" +
" }\n" +
" h1{\n" +
" width: 400px;\n" +
" height: auto;\n" +
" margin: 0 auto;\n" +
" }\n" +
" table{\n" +
" width: 400px;\n" +
" height: auto;\n" +
" margin: 0 auto;\n" +
" }\n" +
" </style>\n" +
"</head>\n" +
"<body>\n" +
" <div>\n" +
" <table> \n" +
" <tr><td>賬號:</td><td>" + admin +"</td></tr> \n" +
" <tr><td>密碼:</td><td>" + password +"</td></tr>\n" +
" <tr><td>上次登陸時間:</td><td>" + date + "</td></tr>\n" +
" <tr><td colspan=\"2\"><a href=\"\">刪除cookie</a></td></tr>\n" +
" </table>\n" +
" </div>\n" +
"</body>\n" +
"</html>");
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
}
單相思的情場失意,原本糟糕的心情隨着一晚上的代碼時光慢慢變好,現在依舊沒有絲毫睡意,這難道就是學習使我快樂嗎?
我還是和我現任女友好好處吧曬出來一起養養眼
emm~繼續講,接下來就是刪除cookie了,很簡單就是設置maxAge爲0就行了!
這個是自己寫的無法正常刪除cookie的代碼(too young啊):
package cn.jxufe;
import javax.servlet.RequestDispatcher;
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 java.io.IOException;
@WebServlet(name = "DeleteCookieServlet")
public class DeleteCookieServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
Cookie[] cookies = request.getCookies();
if(cookies != null)
for(Cookie cookie : cookies)
cookie.setMaxAge(0);
RequestDispatcher dispatcher = request.getRequestDispatcher("index.jsp");
dispatcher.forward(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
}
關於cookie的壽命信息:
在代碼中,我們用Cookie.setMaxAge()設置Cookie的生命週期。在這個方法中如果沒有參數的話,默認參數就是-1,表示是會話時期cookie,當結束會話或關閉瀏覽器就會刪除。當設置了一個正值,即生命週期是這個正值的秒數,cookie將會保存至硬盤。而像上面那樣直接設置爲0,即直接刪除該Cookie!
運行代碼發現無法正常刪除,查找原因發現是因爲沒有執行response.addCookie()將原來的cookie覆蓋!
加上試試。
點擊刪除cookie,返回登錄界面時還是有的,因爲網頁有緩存,刷新下就沒有了!
還有Cookie.setPath()和Cookie.setDomain()的作用。
http://這裏是domain/這裏是path
上面可以看到url中的domain部分和path部分
cookie設定了domain和path之後,只允許同domain以及同path的頁面訪問。
可以看看這個博客:點擊打開鏈接