具體進修Java Cookie技巧(用戶登錄、閱讀、拜訪權限)。本站提示廣大學習愛好者：（具體進修Java Cookie技巧(用戶登錄、閱讀、拜訪權限)）文章只能為提供參考，不一定能成為您想要的結果。以下是具體進修Java Cookie技巧(用戶登錄、閱讀、拜訪權限)正文
本章文章具體講授：
1、Cookie根本用法演示
2、演示Cookie的拜訪權限
3、演示Cookie的刪除
4、應用Cookie顯示用戶前次登錄的時光
5、應用Cookie技巧顯示用戶比來閱讀的若干個圖片
6、測試火狐閱讀器究竟支撐若干個Cookie和一個Cookie最年夜為多年夜
1、Cookie根本用法演示
index.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> </head> <body> <h1>演示Cookie技巧</h1> <a href="CookieDemo">Cookie根本用法演示</a><br/> </body> </html>
web.xml:
<?xml version="1.0" encoding="UTF-8"?> <web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"> <display-name></display-name> <servlet> <servlet-name>CookieDemo</servlet-name> <servlet-class>cn.hncu.servlets.CookieDemo</servlet-class> </servlet> <servlet-mapping> <servlet-name>CookieDemo</servlet-name> <url-pattern>/CookieDemo</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
CookieDemo.java:
package cn.hncu.servlets;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CookieDemo extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
//向客戶端寫cookie
Random r = new Random();
int n =r.nextInt(100);
String name = "jack";//cookie的格局：key=value
Cookie c = new Cookie("name", name+n);
c.setMaxAge(60*60);//設置過時時光，以秒為單元
c.setPath( request.getContextPath() );//該途徑是: /項目名
//Cookie機制中，是經由過程path來掌握權限的。只要<url-pattern>和該path雷同或是它的子途徑的servlet能力夠拜訪該cookie
//假如把一個cookie的path設為項目根目次，那末該項面前目今的一切servlet都可以或許拜訪它
response.addCookie(c);
//這一段演示cookie帶中文
String str = "我帶中文";
str = URLEncoder.encode(str, "utf-8");//中文設置編碼！！！urlencode編碼
Cookie cStr = new Cookie("str", str);
//假如不設置setMaxAge，則閱讀器一封閉就過時
cStr.setPath("/");
response.addCookie(cStr);
//讀取客戶端發過去的cookie
Cookie cs[] = request.getCookies();//讀取cookie
if(cs!=null){//防備一下
for(Cookie cc:cs){
String name2 = cc.getName();
String val = cc.getValue();
val = URLDecoder.decode(val, "utf-8");//本來是怎樣編碼的，就怎樣解碼！ 中文解碼，ascii是原樣的！
out.print(name2+"="+val+"<br/>");
}
}
out.print("Cook保留勝利！");
}
}
演示成果：
第一次點擊時！session下次講！tomcat主動生成發給客戶真個！
再次進入時！
name+n–由於前面的n一向在隨機生成，這個點擊老是顯示的是前一個的信息！
2、演示Cookie的拜訪權限
index.jsp:
<a href="servlet/CookieDemo2">演示Cookie的拜訪權限</a><br/> web.xml: <servlet> <servlet-name>CookieDemo2</servlet-name> <servlet-class>cn.hncu.servlets.CookieDemo2</servlet-class> </servlet> <servlet-mapping> <servlet-name>CookieDemo2</servlet-name> <url-pattern>/servlet/CookieDemo2</url-pattern> </servlet-mapping>
CookieDemo2.java:
package cn.hncu.servlets;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Random;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CookieDemo2 extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
//向客戶端寫Cookie
Random r = new Random();
int n =r.nextInt(100);
Cookie c = new Cookie("age", ""+n);
c.setMaxAge(60*60);//過時時光
c.setPath( request.getContextPath()+"/servlet/CookieDemo2" );//Cookie機制中,是經由過程path來掌握權限的
//因為CookieDemo的url-pattern是項目根目次/CookieDemo，不是以後cookie所設途徑的子目次，是以沒法拜訪到該cookie
//留意！！！path紛歧樣，那末cookie是分歧的對象，也就是不會覆誰人名字雷同的cookie！
response.addCookie(c);
//讀取從客戶端發來的cookie
Cookie cs[] = request.getCookies();
if(cs!=null){
for(Cookie cc:cs){
String name = cc.getName();
String val = cc.getValue();
out.print("22222--"+name+"="+val+"<br/>");
}
}
out.print("Cookie保留勝利！");
}
}
演示成果：
先輩入CookieDemo2的頁面，能拜訪到CookieDemo的name-cookie
再進入CookieDemo的頁面，不克不及拜訪到CookieDemo2的age-cookie
3、演示Cookie的刪除
index.jsp:
<a href="servlet/DelCookieDemo"> 演示Cookie的刪除 </a><br/>
web.xml:
<servlet> <servlet-name>DelCookieDemo</servlet-name> <servlet-class>cn.hncu.servlets.DelCookieDemo</servlet-class> </servlet> <servlet-mapping> <servlet-name>DelCookieDemo</servlet-name> <url-pattern>/servlet/DelCookieDemo</url-pattern> </servlet-mapping>
DelCookieDemo.java:
package cn.hncu.servlets;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class DelCookieDemo extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
Cookie cs[] = request.getCookies();
if(cs!=null){
for(Cookie c:cs){
//要想遍歷到"name"這個cookie，以後servlet必需要有讀的權限，即servlet的url-pattern必需是該cookie所設途徑或許是其所設途徑的子途徑
//刪除name這個cookie
if("name".equals(c.getName())){
c.setPath( request.getContextPath() );//刪除時是經由過程這一句來斷定權限的！這裡必需和本來所設的途徑完整一樣能力刪除，不然不克不及刪除！
//關於上句，我的小我懂得是：由於假如你這個途徑設置分歧了，其實只是相當與新開了一個cookie，這個新cookie的到期時光是0，name是"name"
c.setMaxAge(0);//到期時見設為0，等於刪除---此處只是設置刪除標識
response.addCookie(c);
}
}
}
}
}
演示成果：
這個時刻，name還存在的。
我們拜訪DelCookieDemo.
再去第一個鏈接看：
name曾經沒有了！
火狐會主動刪除過時的cookie：
4、應用Cookie顯示用戶前次登錄的時光
index.jsp:
<a href="LoginServlet">應用Cookie顯示用戶前次登錄的時光</a>
web.xml:
<servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>cn.hncu.servlets.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/LoginServlet</url-pattern> </servlet-mapping>
LoginServlet.java:
package cn.hncu.servlets;
import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>演示應用Cookie顯示用戶前次登錄的時光</TITLE></HEAD>");
out.println(" <BODY>");
//讀取客戶真個cookie
Cookie cs[] = request.getCookies();
boolean boo = false;
if(cs!=null){
for(Cookie c:cs){
//遍歷
if("loginTime".equals(c.getName())){
String val =c.getValue();
long dt = Long.parseLong(val);
Date d = new Date(dt);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
out.print("您前次登錄時光是："+sdf.format(d));
boo=true;
break;
}
}
}
if(boo==false){//表現之前1年沒有拜訪記載！由於上面我們保留的過時時光是一年
out.print("您比來一年是第一次拜訪。。。");
}
//不管是新舊用戶，都邑以比來的時光倆創立一個Cookie，寫到客戶端。本來有了的，就是更新時光
Date d = new Date();
Cookie c = new Cookie("loginTime", ""+d.getTime() );
c.setPath(request.getContextPath());
c.setMaxAge(60*60*24*30*12);
response.addCookie(c);
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}
演示成果：
第一次拜訪;
再次拜訪：
5、應用Cookie技巧顯示用戶比來閱讀的若干個圖片
index.jsp:
<a href="jsps/show.jsp">看美男--應用Cookie技巧顯示用戶比來閱讀的若干個圖片</a>
web.xml:
<servlet> <servlet-name>ShowServlet</servlet-name> <servlet-class>cn.hncu.servlets.ShowServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ShowServlet</servlet-name> <url-pattern>/showImg</url-pattern> </servlet-mapping>
show.jsp:
<%@page import="java.io.File"%>
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<style type="text/css">
.span{
border:0px solid #000;
width:100px;
height:100px;
overflow:hidden;
}
.span img{
max-width:100px;
_width:expression(this.width > 100 ? "100px" : this.width);
}
.spans{
border:0px solid #000;
width:50px;
height:50px;
overflow:hidden;
}
.spans img{
max-width:50px;
_width:expression(this.width > 50 ? "50px" : this.width);
}
</style>
</head>
<body>
<h1>看美男--應用Cookie技巧顯示用戶比來閱讀的若干個圖片</h1>
<a href="/myCookieWeb/jsps/show.jsp">看美男--應用Cookie技巧顯示用戶比來閱讀的若干個圖片</a>
<h3>比來閱讀的圖片：</h3>
<!-- 添加比來3次閱讀的圖片 -->
<%
String str =null;
Cookie cs[] = request.getCookies();
if(cs!=null){
for(Cookie c:cs){
if("images".equals(c.getName())){
str=c.getValue();// ***.jpg
break;
}
}
}
if(str!=null){
String strs[] = str.split(",");
for(String s:strs){
%>
<span class="spans">
<img src="<%=request.getContextPath()%>/imgs/<%=s%>" />
</span>
<%
}
}
%>
<br/><hr/><br/>
<%
//應用file遍歷一切的圖片，顯示出來。
String path = getServletContext().getRealPath("/imgs");
//System.out.printf(path);//D:\apache-tomcat-7.0.30\webapps\myCookieWeb\jsps
File file = new java.io.File(path);
File[] files = file.listFiles();
if(files!=null){
%>
<%
for(File f:files){
String imgName = f.getName();
%>
<span class="span">
<a href="<%=request.getContextPath() %>/showImg?img=<%=imgName %>">
<img src="<%=request.getContextPath()%>/imgs/<%=imgName%>" />
</a>
</span>
<%
}
%>
<%
}
%>
</body>
</html>
ShowServlet.java:
package cn.hncu.servlets;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ShowServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
String img = request.getParameter("img");
String imgStr = "<img src='"+request.getContextPath()+"/imgs/"+img+"'/>";
out.print(imgStr);
//用Cookie記載用戶拜訪過的圖片信息
Cookie cs[] = request.getCookies();
boolean boo = false;
if(cs!=null){
for(Cookie c:cs){
if("images".equals(c.getName())){//曾經有了images這個cookie
String imgs = c.getValue();
String imgStrs[] = imgs.split(",");
boolean booStr = false;
//防備點擊反復的圖片
for(int i=0;i<imgStrs.length;i++){
if(imgStrs[i].equals(img)){
if(i==1&&imgStrs.length==2){
imgs=imgStrs[i]+","+imgStrs[0];
}else if(i==2&&imgStrs.length==3){
imgs=imgStrs[i]+","+imgStrs[0]+","+imgStrs[1];
}else if(i==2&&imgStrs.length==3){
imgs=imgStrs[i]+","+imgStrs[0]+","+imgStrs[1];
}
booStr=true;
break;
}
}
if(!booStr){
imgs = img+","+imgs;//采取以下方法會費事一點：imgs+","+img
if(imgs.split(",").length>3){//假如拜訪的圖片跨越3次了
imgs = imgs.substring(0, imgs.lastIndexOf(","));//左包括，右不包括
}
/*//假如如許寫了，最好把下面的防備反復的圖片，誰人添加次序倒過去
//imgs+","+img 方法：
imgs = imgs+","+img;
if(imgs.split(",").length>3){//假如拜訪的圖片跨越3次了
imgs = imgs.substring(imgs.indexOf(",")+1, imgs.length());
}
*/
}
c.setValue(imgs);//更新
c.setMaxAge(60*60*24*30);
c.setPath("/");//相當於把拜訪權限完整攤開，即一切的項目都能拜訪
response.addCookie(c);
boo=true;
break;
}
}
}
if(boo==false){//表現初次拜訪，即閱讀器中沒有圖片閱讀的cookie
Cookie c = new Cookie("images", img);
c.setMaxAge(60*60*24*30);
c.setPath("/");
response.addCookie(c);
}
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}
演示成果：
6、測試火狐閱讀器究竟支撐若干個Cookie和一個Cookie最年夜為多年夜
index.jsp:
<a href="servlet/HowManyCookieServlet">測試火狐閱讀器究竟支撐若干個Cookie和一個Cookie最年夜為多年夜 </a><br/>
web.xml:
<servlet> <servlet-name>HowManyCookie</servlet-name> <servlet-class>cn.hncu.servlets.HowManyCookie</servlet-class> </servlet> <servlet-mapping> <servlet-name>HowManyCookie</servlet-name> <url-pattern>/servlet/HowManyCookieServlet</url-pattern> </servlet-mapping>
HowManyCookie.java:
package cn.hncu.servlets;
import java.io.IOException;
import java.io.PrintWriter;
import java.net.URLDecoder;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HowManyCookie extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
PrintWriter out = response.getWriter();
/*
//測試個數--火狐47.0.1 最年夜支撐110個
for(int i=1;i<=110;i++){
Cookie c = new Cookie("textNum"+i, ""+i);
c.setMaxAge(60*15);
c.setPath("/");
response.addCookie(c);
}
*/
//測試年夜小 ---4092字節為最年夜支撐的單個cookie存儲
String s ="";
for(int i=0;i<4092;i++){
s+="1";
}
Cookie c = new Cookie("test", s);
c.setMaxAge(60*15);
c.setPath("/");
response.addCookie(c);
Cookie cs[] = request.getCookies();//讀取cookie
if(cs!=null){//防備一下
for(Cookie cc:cs){
String key = cc.getName();
String val = cc.getValue();
out.print(key+"="+val+" ");
}
}
}
}
以上就是本文的全體內容，願望對年夜家的進修有所贊助，也願望年夜家多多支撐。
