Javaweb开发核⼼心之Cookie实战

简介：javaweb操作浏览器器cookie

1.创建并发送 Cookie

package com.gaze;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;


@WebServlet("/setCookie")
public class SetCookieServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 创建 Cookie
        Cookie cookie = new Cookie("username", "JohnDoe");

        // 设置有效期（单位：秒，3600秒为1小时）
        cookie.setMaxAge(3600);

        // 设置作用路径
        cookie.setPath("/");

        // 将 Cookie 发送给客户端
        response.addCookie(cookie);

        response.getWriter().println("Cookie 'username' has been set.");
    }
}

cookie.setPath("/")详解：

• cookie 是一个 javax.servlet.http.Cookie 类的实例，它代表了一个HTTP Cookie，通常用于在客户端（用户的浏览器）和服务器之间传递信息。

• setPath(String path) 是 Cookie 类的一个方法，用于指定Cookie的有效路径。这个路径决定了浏览器在哪些URL请求中会包含这个Cookie。

• 当你调用 cookie.setPath("/"); 时，你实际上是在告诉浏览器，这个Cookie对于当前Web应用程序的根目录及其所有子目录下的所有页面都是有效的。换句话说，只要请求的URL是以域名开头

例如：

• 如果你设置 cookie.setPath("/");，那么无论用户访问 http://www.example.com/index.html

• http://www.example.com/products/list.html 是 http://www.example.com/about/us.html，浏览器都会发送这个Cookie。

• 如果你设置 cookie.setPath("/products");，那么这个Cookie只会在用户访问以 /products 开头的页面时发送，如 http://www.example.com/products/list.html，但不会在访问 http://www.example.com/about/us.html 时发送。

Cookie 的设置、读取、修改和删除:

1. package com.gaze;
   
   import javax.servlet.ServletException;
   import javax.servlet.annotation.WebServlet;
   import javax.servlet.http.*;
   import java.io.IOException;
   
   
   @WebServlet("/setCookie")
   public class SetCookieServlet extends HttpServlet {
       protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           // 创建 Cookie
           Cookie cookie = new Cookie("username", "JohnDoe");
   
           // 设置有效期（单位：秒，3600秒为1小时）
           cookie.setMaxAge(3600);
   
           // 设置作用路径
           cookie.setPath("/");
   
           // 将 Cookie 发送给客户端
           response.addCookie(cookie);
   
           response.getWriter().println("Cookie 'username' has been set.");
       }
   }

   package com.gaze;
   
   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("/getCookie")
   public class GetCookieServlet extends HttpServlet {
       protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, IOException {
           Cookie[] cookies = request.getCookies();
           if (cookies != null) {
               for (Cookie cookie : cookies) {
                   // 输出 Cookie 的名称和值
                   response.getWriter().println(cookie.getName() + ": " + cookie.getValue());
               }
           } else {
               response.getWriter().println("No cookies found.");
           }
       }
   }
   

   package com.gaze;
   
   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("/deleteCookie")
   public class DeleteCookieServlet extends HttpServlet {
       protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
           Cookie cookieToDelete = new Cookie("username", null);
           cookieToDelete.setMaxAge(0); // 设置有效期为 0
           cookieToDelete.setPath("/");
           response.addCookie(cookieToDelete);
   
           response.getWriter().println("Cookie has been deleted.");
       }
   }
   

   package com.gaze;
   
   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("/updateCookie")
   public class UpdateCookieServlet extends HttpServlet {
       protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException, IOException {
           Cookie updatedCookie = new Cookie("username", "JaneDoe");
           updatedCookie.setMaxAge(3600); // 更新有效期
           updatedCookie.setPath("/");
           response.addCookie(updatedCookie);
   
           response.getWriter().println("Cookie has been updated.");
       }
   }
   

   注意：js获取cookie，可以获取token，但是获取不不到JSESSIONID,因为 http-only原因