7. Request, Response 객체 이해하기
1) 요청과 응답
WAS는 웹 브라우저로부터 Servlet요청을 받으면, 요청할 때 가지고 있는 정보를 HttpServletRequest객체를 생성하여 저장한다.
웹 브라우저에게 응답을 보낼 때 사용하기 위하여 HttpServletResponse객체를 생성한다.
생성된 HttpServletRequest, HttpServletResponse 객체를 서블릿에게 전달한다.
2) HttpServletRequest (요청 서블릿)
http프로토콜의 request정보를 서블릿에게 전달하기 위한 목적으로 사용한다.
헤더정보, 파라미터, 쿠키, URI, URL 등의 정보를 읽어 들이는 메소드를 가지고 있다.
Body의 Stream을 읽어 들이는 메소드를 가지고 있다.
3) HttpServletResponse (응답 서블릿)
WAS는 어떤 클라이언트가 요청을 보냈는지 알고 있고, 해당 클라이언트에게 응답을 보내기 위한 HttpServleResponse객체를 생성하여 서블릿에게 전달한다.
서블릿은 해당 객체를 이용하여 content type, 응답코드, 응답 메시지 등을 전송한다.
4) 실습코드 - HeaderServlet.java
package examples;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class HeaderServlet
*/
@WebServlet("/header")
public class HeaderServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public HeaderServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head><title>form</title></head>");
out.println("<body>");
Enumeration<String> headerNames = request.getHeaderNames();
while(headerNames.hasMoreElements()) {
String headerName = headerNames.nextElement();
String headerValue = request.getHeader(headerName);
out.println(headerName + " : " + headerValue + " <br> ");
}
out.println("</body>");
out.println("</html>");
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}5) 실습코드 - ParameterServlet.java
package examples;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class ParameterServlet
*/
@WebServlet("/param")
public class ParameterServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ParameterServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head><title>form</title></head>");
out.println("<body>");
String name = request.getParameter("name");
String age = request.getParameter("age");
out.println("name : " + name + "<br>");
out.println("age : " +age + "<br>");
out.println("</body>");
out.println("</html>");
}
}6) 실습코드 - InfoServlet.java
package examples;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class InfoServlet
*/
@WebServlet("/info")
public class InfoServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public InfoServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head><title>info</title></head>");
out.println("<body>");
String uri = request.getRequestURI();
StringBuffer url = request.getRequestURL();
String contentPath = request.getContextPath();
String remoteAddr = request.getRemoteAddr();
out.println("uri : " + uri + "<br>");
out.println("url : " + url + "<br>");
out.println("contentPath : " + contentPath + "<br>");
out.println("remoteAddr : " + remoteAddr + "<br>");
out.println("</body>");
out.println("</html>");
}
}
Back-End Engineer