文章目录
Cookie的详解使用(创建,获取,销毁)
1、Cookie是什么
cookie是在浏览器中保存的
如果想要使用cookie要保证我们的浏览器是开启cookie,所以说有一定的弊端,如果浏览器没有开启cookie,就不能再使用cookie了
cookie的大小是有限制的,通常是4096byte
cookie的保存是以键值对的形式存在的
2、cookie的常用方法
java
//1.cookie的构造方法,目的是实例化出来cookie对象
Cookie(String name,String value)
//2.设置cookie的方法
setValue(String value) //修改cookie的值
getValue(String value) //获得cookie的值
getName(String value) //获得cookie的键
setMaxAge(int time) //设置cookie的有效时间
//3.要将cookie发送到浏览器
response.addCookie(Cookie cookie);
//4.获得所有cookie
request.getCookies();
3、cookie的构造和获取代码演示
SetCookieServlet.java
java
/*
* Copyright (c) 2020, 2023, fpl1116.cn All rights reserved.
*
*/
package cn.fpl.servlet;
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;
/**
* <p>Project: JavaWebDemo - SetCookieServlet</p>
* <p>Powered by fpl1116 On 2023-12-27 09:50:33</p>
* <p>描述:<p>
*
* @author fpl1116 [2391940642@qq.com]
* @version 1.0
* @since 1.8
*/
public class SetCookieServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//创建cookie对象
Cookie cookie = new Cookie("fpl","fpl1116");
//设置过期时间
cookie.setMaxAge(60*60*24);
//发送浏览器响应
resp.addCookie(cookie);
}
}
GetCookieServlet.java
java
/*
* Copyright (c) 2020, 2023, fpl1116.cn All rights reserved.
*
*/
package cn.fpl.servlet;
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.util.ArrayList;
/**
* <p>Project: JavaWebDemo - SetCookieServlet</p>
* <p>Powered by fpl1116 On 2023-12-27 09:50:33</p>
* <p>描述:<p>
*
* @author fpl1116 [2391940642@qq.com]
* @version 1.0
* @since 1.8
*/
public class GetCookieServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
Cookie[] cookies = req.getCookies();
for(Cookie cookie : cookies){
System.out.println("=============");
System.out.println(cookie.getName());
System.out.println(cookie.getValue());
}
}
}
web.xml
java
<servlet>
<servlet-name>setcookie</servlet-name>
<servlet-class>cn.fpl.servlet.SetCookieServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>setcookie</servlet-name>
<url-pattern>/setcookie</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>getcookie</servlet-name>
<servlet-class>cn.fpl.servlet.GetCookieServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>getcookie</servlet-name>
<url-pattern>/getcookie</url-pattern>
</servlet-mapping>
运行结果如下
setcookie
getcookie
4、Cookie的销毁
DestoryCookieServlet
java
package cn.fpl.servlet;
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;
public class DestoryCookieServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doPost(req, resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//获得所有cookie
Cookie[] cookieArr = req.getCookies();
for (Cookie cookie : cookieArr) {
if("fpl".equals(cookie.getName())){
//修改fpl的失效时间
cookie.setMaxAge(0);
resp.addCookie(cookie);
}
}
}
}
web.xml
java
<servlet>
<servlet-name>destoryCookie</servlet-name>
<servlet-class>cn.fpl.servlet.DestoryCookieServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>destoryCookie</servlet-name>
<url-pattern>/destoryCookie</url-pattern>
</servlet-mapping>