Java获取Cookie里的指定值的实现方法

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
public class CookieUtils {
    public static String getCookieValue(HttpServletRequest request, String cookieName) {
        Cookie[] cookies = request.getCookies();
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                if (cookie.getName().equals(cookieName)) {
                    return cookie.getValue();
                }
            }
        }
        return null;
    }
}

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
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 {
        String cookieValue = CookieUtils.getCookieValue(request, "myCookie");
        if (cookieValue != null) {
            response.getWriter().println("Cookie值为：" + cookieValue);
        } else {
            response.getWriter().println("未找到指定Cookie值");
        }
    }
}

@WebServlet("/login")
public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        Cookie cookie = new Cookie("username", username);
        cookie.setMaxAge(24 * 60 * 60); // 设置Cookie的生命周期为1天
        response.addCookie(cookie);
        response.getWriter().println("登录成功！欢迎，" + username);
    }
}

@WebServlet("/userInfo")
public class UserInfoServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = CookieUtils.getCookieValue(request, "username");
        if (username != null) {
            response.getWriter().println("欢迎回来，" + username);
        } else {
            response.getWriter().println("请先登录");
        }
    }
}