HttpServletResponse- 기본 사용법

HttpServletResponse 역할

HTTP 응답 메시지 생성

• HTTP 응답코드 지정
• 헤더 생성
• 바디 생성

편의 기능 제공

• Content-Type,쿠키,Redirect

HttpServletResponse - 기본 사용법

package hello.servlet.basic.response;

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.Cookie;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;
import java.io.PrintWriter;

@WebServlet(name = "responseHeaderServlet", urlPatterns = "/response-header")
public class ResponseHeaderServlet extends HttpServlet {

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //[status-line]
        response.setStatus(HttpServletResponse.SC_OK);

        //[response-headers]
        response.setHeader("Content-Type", "text/plain;charset=utf-8");
        response.setHeader("Cache-Control", "no-cache, no-store ,must-revalidate");
        response.setHeader("Pragma", "no-cache");
        response.setHeader("my-header", "hello");

        // [ Header 의 편의 메서드 ]
//        content(response);
//        cookie(response);
//          redirect(response);

    //[message body]
        PrintWriter writer = response.getWriter();
        writer.println("OK");
    }

    private void content(HttpServletResponse response) {
        //Content-Type: text/plain;charset=utf-8
        //Content-Length: 2
        //response.setHeader("Content-Type", "text/plain;charset=utf-8");
        response.setContentType("text/plain");
        response.setCharacterEncoding("utf-8");
        //response.setContentLength(2); //(생략시 자동 생성)
    }

    private void cookie(HttpServletResponse response) {
        //Set-Cookie: myCookie=good; Max-Age=600;
        //response.setHeader("Set-Cookie", "myCookie=good; Max-Age=600");
        Cookie cookie = new Cookie("myCookie", "good");
        cookie.setMaxAge(600); //600초
        response.addCookie(cookie);
    }

    private void redirect(HttpServletResponse response) throws IOException {
        //Status Code 302
        //Location: /basic/hello-form.html
        //response.setStatus(HttpServletResponse.SC_FOUND); //302
        //response.setHeader("Location", "/basic/hello-form.html");
        response.sendRedirect("/basic/hello-form.html");
    }
}

이런식으로 응답값을 제어할수있는데 Content부분은 contetn함수처럼 사용할수있고 즉 간략하게 표시할수있다는 말이다 쿠키또한 마찬가지이고 redirect는 굳이 SC_FOUND를 사용하지않고 어디로 보낼지만 명시해주면 302코드로 응답을 한후 원하는 페이지로 리다이렉트 된다!!