09월 30일 월 | JSP 17 - Servlet

 

Servlet이란?

자바 웹 어플리케이션 구성요소 중 동적인 처리를 하는 프로그램의 역할

Servlet은 자바의 클래스이다.

서블릿을 사용하려면 HttpServlet클래스를 상속받아야한다.

 

Edwith 참고 >

https://www.edwith.org/boostcourse-web/lecture/16686/

 

 

Servlet의 LifeCycle

package net.control;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LifeCycle extends HttpServlet {
/*
    web.xml에 LifeCycle서블릿 등록
    
    결과확인
    http://localhost:8090/mvcTest/life.do
    
    class GenericServlet{}
    class HttpServelt extends GenericServlet{} 
     
    HttpServelt 생명주기----------------------  
     init() 서블릿이 시작되면 한번만 호출
     > service() 사용자가 요청할 때마다 호출
     > destroy() 서버가 중지되면 한번만 호출
     
    ------------------------------------------  
 */
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // method=get방식 요청이 들어오면
        super.doGet(req, resp);
        System.out.println("doGet()호출...");
    }//doGet() end

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // method=post방식 요청이 들어오면
        super.doPost(req, resp);
        System.out.println("doPost()호출...");
    }//doPost() end

    @Override
    protected void service(HttpServletRequest arg0, HttpServletResponse arg1)
            throws ServletException, IOException {
        //method=get방식으로 요청되면 doGet() 호출
        //method=post방식으로 요청되면 doPost()를
        //구분해서 호출하는 역할
        super.service(arg0, arg1);
        System.out.println("service()호출...");
    }//service() end

    @Override
    public void destroy() {
        //서버가 중지되면 1번만 자동 호출
        super.destroy();
        System.out.println("destroy()호출...");
    }//destroy() end

    @Override
    public void init() throws ServletException {
        //서블릿이 최초로 호출될때 1번만 자동 호출
        //초기환경 구축할때 사용
        super.init();
        System.out.println("init()호출...");
    }//init() end  
    
}//class end

 

 

 

로그인세션 구현하기

기능(control)단과 뷰(view)단을 분리한 방법이다. MVC 패턴 참고

 

기능단

1) loginForm.java

package net.control;
import java.io.IOException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginForm extends HttpServlet {
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		/*// TODO Auto-generated method stub
		//1) 단순 경로이동하는 방법.
		resp.sendRedirect("control/loginForm.jsp");*/
		
		//2) RequestDispatcher를 통해 경로이동, 원래 폴더 경로가 나오지 않는다.
		String view = "control/loginForm.jsp";
		RequestDispatcher rd = req.getRequestDispatcher(view);
		rd.forward(req, resp);
	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		// TODO Auto-generated method stub
	}
	//결과확인
	//http://localhost:8090/MVCTest/login.do	
}

 

2) loginProc.java

package net.control;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginProc extends HttpServlet {

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		process(req, resp);
	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		process(req, resp);
	}
	
	
	protected void process(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		
		try {
			//1) 한글 인코딩.
			resp.setCharacterEncoding("UTF-8");
			
			//2) 사용자가 요청한 정보를 변수에 옮겨담기.
			String uid = req.getParameter("uid").trim();
			String upw = req.getParameter("upw").trim();
			
			//*공유공간* request, session, application
			//Session 객체선언
			HttpSession session = req.getSession();
			//Application 객체 선언
			ServletContext application = req.getServletContext();
			
			if(uid.equals("skyhigh") && upw.equals("1234")) {
				req.setAttribute("r_uid", uid);
				req.setAttribute("r_upw", upw);
				
				session.setAttribute("s_uid", uid);
				session.setAttribute("s_upw", upw);
				
				application.setAttribute("a_uid", uid);
				application.setAttribute("a_upw", upw);
				
				req.setAttribute("msg", "로그인성공!!");
				req.setAttribute("img", "<img src='control/checked.png' width=30>");
			} else {
				//로그인 실패시
				req.setAttribute("r_uid", "guest");
				req.setAttribute("r_upw", "guest");
				
				session.setAttribute("s_uid", "guest");
				session.setAttribute("s_upw", "guest");
				
				application.setAttribute("a_uid", "guest");
				application.setAttribute("a_upw", "guest");
				
				req.setAttribute("msg", "로그인실패!!");
				req.setAttribute("img", "<img src='control/report.png' width=30>");
			}
			
			
			//뷰페이지 이동
			String view = "control/loginResult.jsp";
			RequestDispatcher rd = req.getRequestDispatcher(view); 
			rd.forward(req, resp);			
			
		} catch(Exception e) {
			System.out.println("요청실패" + e);
		}
		
	}
	
	
}

 

 

뷰단

1) loginForm.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>

<h2>Login</h2>
<form name="loginfrm" 
	  method="post" 
	  action="loginProc.do"
	  onsubmit="return loginCheck(this)">

	<table class="table">
		<tr>
			<th>아이디</th>
			<td><input type="text" name="uid" size="10" placeholder="아이디를 입력하세요."
				required class="form-control" ></td>
		</tr>
		<tr>
			<th>비밀번호</th>
			<td><input type="password" name="upw" size="30" placeholder="비밀번호를 입력하세요."
				required class="form-control"></td>
		</tr>
		
		<tr>
			<td colspan="2">
			<input type="submit" value="로그인" class="btn btn-primary">
			<input type="reset"  value="취소" class="btn btn-outline-secondary">			
			</td>
		</tr>
	</table>
</form>

 

2) loginResult.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>

<html>
<head>
<meta charset="UTF-8">
<title>Login Result</title>
</head>
<body>
	<h1>로그인 결과</h1>
	<strong>1) JSP</strong>
	<hr>	
	메세지: <%=request.getAttribute("msg")%><br>
	이미지: <%=request.getAttribute("img")%>
	<hr>
	아이디: <%=request.getAttribute("r_uid")%><br>
	비밀번호: <%=request.getAttribute("r_upw")%>
	<hr>
	아이디: <%=session.getAttribute("s_uid")%><br>
	비밀번호: <%=session.getAttribute("s_upw")%>
	<hr>
	아이디: <%=application.getAttribute("a_uid")%><br>
	비밀번호: <%=application.getAttribute("a_upw")%>
	<hr>
	
</body>
</html>