Cookie 사용하기

웹 프로그래밍을 하다 보면 자연스럽게 나오게 되는 부분이 쿠키(Cookie)이다.
Java에서도 쿠키를 사용할 수 있는데, 다음과 같은 방식으로 사용하면 된다.

1. Cookie 객체 생성

Cookie cookie = new Cookie("username", name);

2. Cookie 생명 주기 설정

cookie.setMaxAge(30*60);  //30분...

3. Response에 Cookie 추카

response.addCookie(cookie);

4. Request에서 Cookie 일어오기

Cookie[] cookies = request.getCookies();
for(int i = 0 ; i<cookies.length ; i++) {
  Cookie cookie = cookies[i];
  if(cookie.getName().equals("username")) {
    String userName = cookie.getValue();
    out.println("Hello " + userName);
    break;
  }
}

예제

1. 쿠키를 생성하고 설정하는 서블릿

package com.example;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
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 CookieTest extends HttpServlet {
    public void doPost(HttpServletRequest request, HttpServletResponse response)
                    throws IOException, ServletException {
        response.setContentType("text/html");
        String name = request.getParameter("username");
       
        Cookie cookie = new Cookie("username", name);
        cookie.setMaxAge(30*60);
        response.addCookie(cookie);
       
        RequestDispatcher view = request.getRequestDispatcher("cookieresult.jsp");
        view.forward(request, response);
    }
}

2. 간단한 사용자 정의 쿠키 예제

package com.example.web;

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 CheckCookie extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)
                    throws IOException, ServletException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
       
        Cookie[] cookies = request.getCookies();
       
        for(int i=0 ; i<cookies.length ; i++) {
            Cookie cookie = cookies[i];
            if(cookie.getName().equals("username")) {
                String userName = cookie.getValue();
                out.println("Hello " + userName);
                break;
            }
        }
    }
}