HTTP 응답 데이터 - API JSON

package hello.servlet.basic.response;

import com.fasterxml.jackson.databind.ObjectMapper;
import hello.servlet.basic.HelloData;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import java.io.IOException;

@WebServlet(name = "responseJsonServlet",urlPatterns = "/response-json")
public class ResponseJsonServlet extends HttpServlet {

    private ObjectMapper objectMapper = new ObjectMapper();
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("application/json");
        resp.setCharacterEncoding("utf-8");

        HelloData helloData = new HelloData();
        helloData.setUsername("kim");
        helloData.setAge(20);

        String result = objectMapper.writeValueAsString(helloData);
        resp.getWriter().write(result);

    }
}

 

 

HTTP 응답으로 JSON을 반환할 때는 content-type을 application-json으로 지정해야 한다.

Jackson 라이브러리가 제공하는 objectMapper.writeValueAsString을 사용하면 객체를 JSON 문자로 변경할 수 있다