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9/5 <%! %>, application, request, error 처리하는 여러가지 방법, 서블릿 구조 init, doGet, doPost, destroy 본문

프로젝트 기반 JAVA 응용 SW개발 : 22.07.19~23.01.20/Servlet, JSP

9/5 <%! %>, application, request, error 처리하는 여러가지 방법, 서블릿 구조 init, doGet, doPost, destroy

hayoung.dev 2022. 9. 12. 19:37

num.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>숫자를 입력하세요</h1>
 <form action="num.jsp" name="frm" > 
	<!-- <form action="num3.jsp" name="frm" > -->
	숫자 : <input type="text" name="num"><p>
	<input type="submit" value="확인">
</form>
</body>
</html>

num.jsp

<%@ page language="java" contentType="text/html; charset=EUC-KR"
	pageEncoding="EUC-KR"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="EUC-KR">
<title>Insert title here</title>
<%
	int num = Integer.parseInt(request.getParameter("num"));
	int sum = 0;
	for (int i = 1; i <= num; i++) {
		sum += i;
	}
%>
</head>
<body>
	<h1>1부터<%=num%>까지 합</h1>
	<%=sum%>
</body>
</html>

출력 결과

 

num3.jsp

<%@ page language="java" contentType="text/html; charset=EUC-KR"
	pageEncoding="EUC-KR"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="EUC-KR">
<title>Insert title here</title>
<%
	int num = Integer.parseInt(request.getParameter("num"));
	int sum = 0;
	for (int i = 1; i <= num; i++) {
		sum += i;
		out.println(i + "일때 합계는 " + sum + "<p>");
	}
%>

</head>
<body>
</body>
</html>

 

출력 결과

 

[JSP 선언문]

<%! %>

 

[JSP 페이지의 내장 변수]

 

power.jsp

<%@ page language="java" contentType="text/html; charset=EUC-KR"
    pageEncoding="EUC-KR"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="EUC-KR">
<title>Insert title here</title>
</head>
<body>

<!-- 선언 -->
<%!
int power(int x, int y) {
	int result = 1;
	for (int i = 0; i<y; i++) {
		result *= x;
	}
	return result;
}
%>

2^1 = <%=power(2,1) %><p>
2^2 = <%=power(2,2) %><p>
2^3 = <%=power(2,3) %><p>
2^4 = <%=power(2,4) %><p>
2^5 = <%=power(2,5) %><p>

</body>
</html>

출력 결과

 

select.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1>보고 싶은 것을 선택하시오</h1> 
<form action="select.jsp">
	   배경<input type="radio" name="pgm"   value="color1"><br>
	  구구단<input type="radio" name="pgm"   value="gugu1"><br>
 	네이버<input type="radio" name="pgm"    value="response"><br>
	<input type="submit" value="선택완료"><br>
</form>
</body>
</html>

select.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
    String[] col={"red","orange","yellow","green","blue","navy","violet","black"};
    // 8미만 숫자가 랜덤하게 나옴.
	int n = (int)(Math.random() * 8);
	// color1.jsp, gugu1.jsp,  response.jsp
	String pgm = request.getParameter("pgm") + ".jsp";
	/* RequestDispatcher : form문 없이 page를 이동할 필요가 있을 때 사용하는 객체 */
	/* pgm페이지로 이동하겠다. */
	RequestDispatcher rd = request.getRequestDispatcher(pgm);
	if (pgm.equals("color1.jsp")) {
		// 변수 선언
		//setAttribute로 보내면 getAttribute로 받아야 한다.
		request.setAttribute("color", col[n]);
	//	rd = request.getRequestDispatcher("color1.jsp");
	} else if (pgm.equals("gugu1.jsp")) {
		// 2단 ~ 9단  
		request.setAttribute("num", n + 2);
	//	rd = request.getRequestDispatcher("gugu1.jsp");
	}  else  if (pgm.equals("response.jsp")) {
		// 예비
	} 
	// 2. 이동 Page를 지정하는 객체 선언를 실제적으로 이동
	//form문은 url에 표시되지만, 이 방법으로 이동하면 url에 표시되지 않는다.
	rd.forward(request, response);

%>
</body>
</html>

color1.jsp

<%@ page language="java" contentType="text/html; charset=EUC-KR"
    pageEncoding="EUC-KR"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="EUC-KR">
<title>Insert title here</title>
</head>
<%
   //선언한 변수 꺼내는 방법
   //setAttribute로 보내면 getAttribute로 받아야 한다.
   //문자로 받을 때는 .toString() 사용.
	String color = request.getAttribute("color").toString();
%>
<body bgcolor="<%=color %>">

</body>
</html>

출력 결과

gugu1.jsp

<%@ page language="java" contentType="text/html; charset=EUC-KR"
    pageEncoding="EUC-KR"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="EUC-KR">
<title>Insert title here</title>
</head>
<%
	int num = Integer.parseInt(request.getAttribute("num").toString());
	out.println("<h1>구구단 " + num + "단</h1>");
	for (int i=1; i<=9; i++) {
		out.println(num + " * " + i + " = " + (num * i)+"<br>");
	}
%>
<body>

</body>
</html>

출력 결과

response.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%
	/* sendRedirect : 페이지 이동 방법 */
	response.sendRedirect("http://naver.com");
%>
</body>
</html>

출력 결과

 

 

 

[och04]

[웹 어플리케이션 내부 객체의 영역 : page, request, session, application]

 

application.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<%
		String info = application.getServerInfo();
		int major = application.getMajorVersion();
		int minor = application.getMinorVersion();
		String path = application.getRealPath("/");
	%>
	<h2>Application내장객체 예제</h2>
	웹 컨테이너의 이름과 버전       : <%=info%><p>
		서블릿의 버전            : <%=major%>.<%=minor%><p>
웹 어플리케이션 폴더의 로컬 시스템 경로 : <%=path%>
</body>
</html>

출력 결과

 

request.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<%	
	        String protocol = request.getProtocol();
			String server = request.getServerName();
			int port = request.getServerPort();
			String clientIp = request.getRemoteAddr();
			String clientHost = request.getRemoteHost();
			String methodType = request.getMethod();
			String url = new String(request.getRequestURL());
			String uri = request.getRequestURI();
			String contextPath = request.getContextPath();
	%>
	<h2>Request내장 객체 예제2</h2>
	프로토콜명          :	<%=protocol%><p>
	접속한 서버명        :	<%=server%>	<p>
	접속한 서버의 포트 번호 :  <%=port%>	<p>
	클라이언트의 IP      :	<%=clientIp%>	<p>
	클라이언트의 호스트명   :	<%=clientHost%>	<p>
	현재 페이지의 method방식     :	<%=methodType%>	<p>
	요청한 현재 페이지의 경로(URL) :	<%=url%>	<p>
	요청한 현재 페이지의 경로(URI) :	<%=uri%>	<p>
	웹어플리케이션에서의 컨텍스트 경로 :	<%=contextPath%>	<p>
</body>
</html>

출력 결과

 

[och05]

num1.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>연산할 숫자 입력 Servlet 이용한 Error 처리</h2>
<form action="Cal">
<!-- <form action="Cal2"> -->  
	첫번째 숫자 : <input type="text" name="num1"><p>
	두번째 숫자 : <input type="text" name="num2"><p>
	<input type="submit" value="확인">
</form>
</body>
</html>

Cal.java

package och05;

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 Cal
 */
@WebServlet("/Cal")
public class Cal extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Cal() {
        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;charset=utf-8");
		PrintWriter out = response.getWriter();
		out.print("<html><body><h1>연산결과</h1>");
		try {
		int num1 = Integer.parseInt(request.getParameter("num1"));
		int num2 = Integer.parseInt(request.getParameter("num2"));

		out.println(num1 + " + " + num2 + " = " + (num1+num2) + "<p>");
		out.println(num1 + " - " + num2 + " = " + (num1-num2) + "<p>");
		out.println(num1 + " * " + num2 + " = " + (num1*num2) + "<p>");
		out.println(num1 + " / " + num2 + " = " + (num1/num2) + "<p>");
		
	} catch (NumberFormatException e) {
		out.println("연산결과 NumberFormatException");
		
	} catch (ArithmeticException e) {
		out.println("0으로 나누었어");
		
	} catch (Exception e) {
		out.println("e.getMessage()->" + e.getMessage());
		
	}
		out.println("</body></html>");
		out.close();
	}
	/**
	 * @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);
	}

}

출력 결과 (두 번째 숫자를 0으로 입력한 경우)

(두 번째 숫자를 aa로 입력한 경우)

 

Cal2.java

package och05;

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

import javax.servlet.RequestDispatcher;
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 Cal2
 */
@WebServlet("/Cal2")
public class Cal2 extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Cal2() {
        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;charset=utf-8");
		PrintWriter out = response.getWriter();
		out.print("<html><body><h1>연산결과</h1>");
		try {
		int num1 = Integer.parseInt(request.getParameter("num1"));
		int num2 = Integer.parseInt(request.getParameter("num2"));

		out.println(num1 + " + " + num2 + " = " + (num1+num2) + "<p>");
		out.println(num1 + " - " + num2 + " = " + (num1-num2) + "<p>");
		out.println(num1 + " * " + num2 + " = " + (num1*num2) + "<p>");
		out.println(num1 + " / " + num2 + " = " + (num1/num2) + "<p>");
			
	} catch (Exception e) {
		/* 페이지 이동을 통해 에러처리 */
		RequestDispatcher rd = request.getRequestDispatcher("error.jsp");
		rd.forward(request, response);
	}
		out.println("</body></html>");
		out.close();
	}

	/**
	 * @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);
	}

}

error.jsp : error 페이지는 isErrorPage="true"로 error페이지라는 것을 반드시 작성해줘야 한다. 

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" isErrorPage="true"%>
<% 
//200이 정상값이다. 정상값 setting
response.setStatus(200);
%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<h1>공지사항</h1>
	작업중...<p>
</body>
</html>

출력 결과 (두 번째 숫자에 0이나 aa를 입력한 경우)

 

num2.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
function init() {
	frm.num1.value = "100";
	frm.num2.value = "5";
	frm.num1.focus();
}
</script>
</head>
<!-- 초기값 세팅 -->
<body onload="init()">
<h2>연산할 숫자 입력 jsp 이용한 Error 처리</h2>
<form action="cal1.jsp" name="frm">
<!-- <form action="cal2.jsp" name="frm"> -->
<!-- <form action="cal3.jsp" name="frm"> -->
<!-- <form action="cal4.jsp" name="frm">  -->
<!-- <form action="cal5.jsp" name="frm"> -->
		첫번째 숫자 : <input type="text" name="num1"><p>
		두번째 숫자 : <input type="text" name="num2"><p>
		<input type="submit" value="확인">
</form>
</body>
</html>

cal1.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<h2>연산결과</h2>

	<%
	try {
		int num1 = Integer.parseInt(request.getParameter("num1"));
		int num2 = Integer.parseInt(request.getParameter("num2"));
		out.println(num1 + " + " + num2 + " = " + (num1 + num2) + "<p>");
		out.println(num1 + " - " + num2 + " = " + (num1 - num2) + "<p>");
		out.println(num1 + " * " + num2 + " = " + (num1 * num2) + "<p>");
		out.println(num1 + " / " + num2 + " = " + (num1 / num2) + "<p>");

	} catch (NumberFormatException e) {
		out.println("연산결과 NumberFormatException");

	} catch (ArithmeticException e) {
		out.println("0으로 나누었어");

	} catch (Exception e) {
		out.println("e.getMessage()->" + e.getMessage());
	}
	%>

</body>
</html>

cal2.jsp

<%@ page language="java" contentType="text/html; charset=EUC-KR"
	pageEncoding="EUC-KR"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="EUC-KR">
<title>Insert title here</title>
</head>
<body>
	<h2>연산결과 오류 시 error Page 이동</h2>
	<%
	try {
		int num1 = Integer.parseInt(request.getParameter("num1"));
		int num2 = Integer.parseInt(request.getParameter("num2"));

		out.println(num1 + " + " + num2 + " = " + (num1 + num2) + "<p>");
		out.println(num1 + " - " + num2 + " = " + (num1 - num2) + "<p>");
		out.println(num1 + " * " + num2 + " = " + (num1 * num2) + "<p>");
		out.println(num1 + " / " + num2 + " = " + (num1 / num2) + "<p>");

	} catch (Exception e) {
		RequestDispatcher rd = request.getRequestDispatcher("error.jsp");
		rd.forward(request, response);
	}
	%>

</body>
</html>

cal3.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<h2>연산결과 오류시 Java Script 이용 처리</h2>
	<%
	try {
		int num1 = Integer.parseInt(request.getParameter("num1"));
		int num2 = Integer.parseInt(request.getParameter("num2"));
		out.println(num1 + " + " + num2 + " = " + (num1 + num2) + "<p>");
		out.println(num1 + " - " + num2 + " = " + (num1 - num2) + "<p>");
		out.println(num1 + " * " + num2 + " = " + (num1 * num2) + "<p>");
		out.println(num1 + " / " + num2 + " = " + (num1 / num2) + "<p>");

	} catch (NumberFormatException e) {
	%>
	<!-- 자바문 사이사이에 자바스크립트로 처리 -->
	<script type="text/javascript">
		alert("그게 숫자냐");
		//바로 전 페이지로 이동
		history.go(-1);
	</script>
	<%
	} catch (ArithmeticException e) {
	%>
	<script type="text/javascript">
		alert("0으로 못나눠");
		//바로 전 페이지로 이동
		history.back();
	</script>
	<%
	} catch (Exception e) {
	out.println(e.getMessage());
	%>
	<script type="text/javascript">
		alert("하여튼 에러야");
		//페이지 이동
		location.href = "num2.html";
	</script>
	<%
	}
	%>
</body>
</html>

cal4.jsp : try catch문을 걸지 않아도 cal4.jsp를 에러페이지로 지정했기 때문에 에러가 나면 알아서 error2.jsp를 실행시킨다.

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" errorPage="error2.jsp"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>연산결과 error Page이용한 처리</h2>
<%
	int num1 = Integer.parseInt(request.getParameter("num1"));
	int num2 = Integer.parseInt(request.getParameter("num2"));
	out.println(num1 + " + " + num2 + " = " + (num1+num2)+"<p>");
	out.println(num1 + " - " + num2 + " = " + (num1-num2)+"<p>");
	out.println(num1 + " * " + num2 + " = " + (num1*num2)+"<p>");
	out.println(num1 + " / " + num2 + " = " + (num1/num2)+"<p>");
%>
</body>
</html>

error2.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8" isErrorPage="true"%>
<% response.setStatus(200); %>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<h2>공지</h2>
	나은 서비스를 위해서 준비중입니다 <p>
		메세지 : <%=exception.getMessage()%> <p>
		클래스 : <%=exception.getClass()%>
</body>
</html>

cal5.jsp : 에러페이지로 지정하지 않고 web.xml로 에러처리를 한다.

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>연산결과 setting(web.xml) 통한 error 처리</h2>
<%
	int num1 = Integer.parseInt(request.getParameter("num1"));
	int num2 = Integer.parseInt(request.getParameter("num2"));
	out.println(num1 + " + " + num2 + " = " + (num1+num2)+"<p>");
	out.println(num1 + " - " + num2 + " = " + (num1-num2)+"<p>");
	out.println(num1 + " * " + num2 + " = " + (num1*num2)+"<p>");
	out.println(num1 + " / " + num2 + " = " + (num1/num2)+"<p>");
%>
</body>
</html>

main > webapp > WEB-INF > web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
  <display-name>och05</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.jsp</welcome-file>
    <welcome-file>default.htm</welcome-file>
  </welcome-file-list>
  
  <error-page>
  	<exception-type>java.lang.NumberFormatException </exception-type>
  	<location>/error/errorFormat.jsp</location>
  </error-page>
  
  <error-page>
  	<exception-type>java.lang.ArithmeticException</exception-type>
  	<location>/error/errorArith.jsp</location>
  </error-page>
  
</web-app>

main > webapp > error폴더 생성 후 errorFormat.jsp 작성

<%@ page language="java" contentType="text/html; charset=EUC-KR"
    pageEncoding="EUC-KR" isErrorPage="true"%>
<% response.setStatus(200); %>
<!DOCTYPE html>
<html>
<head>
<meta charset="EUC-KR">
<title>Insert title here</title>
</head>
<body>
  <h1>Format을 잘못 입력한거야</h1>
</body>
</html>

error> errorArith.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8" isErrorPage="true"%>
<% response.setStatus(200); %>        
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
	<h1>0으로 나누면 되니</h1>
</body>
</html>

 

[och06]

서블릿 구조 : init, doGet, doPost, destroy

 

name.html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
	function chk() {
		if (!frm.name.value) {
			alert("너 이름이 뭐니 ?");
			frm.name.focus();
			return false;
		}
		return true;
	}
</script>
</head>
<body>
	<h2>이름을 입력하세요</h2>
	<form action="Greet" name="frm" onsubmit="return chk()">
	<!-- <form action="greet.jsp" name="frm" onsubmit="return chk()"> -->
		이름 : <input type="text" name="name"><p>
		<input type="submit" value="확인">
	</form>
</body>
</html>

Greet.java(설정 시 init, destrory도 사용 체크)

package och06;

import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.GregorianCalendar;

import javax.servlet.ServletConfig;
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 Greet
 */
@WebServlet("/Greet")
public class Greet extends HttpServlet {
	//서블릿의 버전 정보. 코드 건들지 않음.
	private static final long serialVersionUID = 1L;
	//파일 이름을 log로 하여 파일 생성
	PrintWriter log;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public Greet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see Servlet#init(ServletConfig)
	 */
	public void init(ServletConfig config) throws ServletException {
		//가장 처음 최초에 실행되는 것
		try {
			System.out.println("init start...");
            //d:/delete/log 폴더가 미리 존재해야 한다.
			log = new PrintWriter(new FileWriter("d:/delete/log/log.txt", true));
		} catch (IOException e) {
			e.printStackTrace();
			System.out.println("에러!");
		}	}

	/**
	 * @see Servlet#destroy()
	 */
	public void destroy() {
		System.out.println("destory start...");
		//죽기 전에 실행되는 것
		//서블릿이 종료가 됐을 때 log가 null이 아니면 닫기.
		if (log != null) log.close();			
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		System.out.println("doGet start...");
		String name = request.getParameter("name");
		String msg = name + "님 반가워\r\n";
		GregorianCalendar gc = new GregorianCalendar();
		String date = String.format("%TF %TT\r\n", gc, gc);
		// File 출력  --> date + msg
		log.print(date + msg);
		response.setContentType("text/html;charset=utf-8");
		PrintWriter out = response.getWriter();
		// 화면 출력  -->  msg
		out.println("<html><body><h2>인사</h2>"+msg);
		out.println("</body></html>");		
        out.close();
	}

	/**
	 * @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);
	}

}

 

실행 결과

처음 접속할 땐 init과 doGet이 실행되는데, 두번째 실행부터는 doGet만 실행된다. init은 맨 처음 초기화하는 작업만 하기 때문이다.

서버를 죽이면 destory가 실행된다.

 

d:/delete/log/log.txt 파일 확인

 

greet.jsp

<%@page import="java.io.FileWriter"%>
<%@page import="java.util.GregorianCalendar"%>
<%@page import="java.io.PrintWriter"%>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<%!
   private PrintWriter  pw;
   String  date;

   public void jspInit() {
	    GregorianCalendar gc = new GregorianCalendar();
	    //날짜와 시간
		date = String.format("%TF %TT", gc, gc);
		System.out.println("date->"+date);
		//date값에는 :이 있는데 파일 이름에는 :을 쓸 수 없기 때문에 :를 없애준다.
		String fileName = "d:/delete/log/" + date.replaceAll(":", "") + ".txt";
		try {
			pw = new PrintWriter(new FileWriter(fileName, true));
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			System.out.println("jspInit 헐 !");
		}	   
   }
%>
<%
	String name = request.getParameter("name");
	String msg = name + "님 반가워 ";
	out.println(msg + "<p> 현재시간 : " + date);
	pw.println(msg + "\r\n 현재시간 : " + date + "\r\n");

%>
<%!
	public void jspDestroy() {
		System.out.println("jspDestroy start...");
		pw.flush();         // buffer 강제출력 
		if (pw != null)		pw.close();
	}	

%>
</body>
</html>

실행 결과

destory가 되면 하단 txt파일이 생긴다.

 

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