12 Servlet 데이터 공유

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관리 메뉴

개발기록

12 Servlet 데이터 공유 본문

JSP

12 Servlet 데이터 공유

옥수수수염챠 2020. 3. 19. 22:10

Servlet에서 데이터를 공유하는 방법에 대해 학습한다.

12-1 servlet parameter

서블릿이 초기화될때 web.xml에서 parameter를 초기화하고,

서블릿 구동시 getInitParameter를 이용하여 초기화된 데이터의 값을 가져온다.

출처 : 실전 JSP (renew ver.) - 신입 프로그래머를 위한 강좌 12강

이전 강의와 다른점은 JSP와 Servlet의 차이일뿐 작동 원리는 동일하다.

xml파일

<?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_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>lec08Pjt001</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <servlet>
  	<servlet-name>servletEx</servlet-name>
  	<servlet-class>com.servlet.ServletEx</servlet-class>
  	<init-param>
  		<param-name>adminId</param-name>
  		<param-value>admin</param-value>
  	</init-param>
  	<init-param>
  		<param-name>adminPw</param-name>
  		<param-value>1234</param-value>
  	</init-param>
  </servlet>
  <servlet-mapping>
  	<servlet-name>servletEx</servlet-name>
  	<url-pattern>/se</url-pattern>
  </servlet-mapping>
</web-app>

java파일

package com.servlet;

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 ServletEx
 */

public class ServletEx extends HttpServlet {

	
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String adminId = getServletConfig().getInitParameter("adminId");
		String adminPw = getServletConfig().getInitParameter("adminPw");
		
		PrintWriter out = response.getWriter();
		out.print("<p>adminId : "+ adminId + "</p>");
		out.print("<p>adminId : "+ adminPw + "</p>");
	}


	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		doGet(request, response);
	}

}

구동 결과 :

12-2 context parameter

이 역시 11강의 JSP context-parameter와 동일하다.

xml 파일

<?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_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>lec08Pjt001</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <context-param>
  	<param-name>imgDir</param-name>
  	<param-value>/upload/img</param-value>
  </context-param>
  <context-param>
  	<param-name>testServerIP</param-name>
  	<param-value>127.0.0.1</param-value>
  </context-param>
  <servlet>
  	<servlet-name>servletEx</servlet-name>
  	<servlet-class>com.servlet.ServletEx</servlet-class>
  	<init-param>
  		<param-name>adminId</param-name>
  		<param-value>admin</param-value>
  	</init-param>
  	<init-param>
  		<param-name>adminPw</param-name>
  		<param-value>1234</param-value>
  	</init-param>
  </servlet>
  <servlet-mapping>
  	<servlet-name>servletEx</servlet-name>
  	<url-pattern>/se</url-pattern>
  </servlet-mapping>
</web-app>

java파일

package com.servlet;

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 ServletEx
 */

public class ServletEx extends HttpServlet {

	
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String adminId = getServletConfig().getInitParameter("adminId");
		String adminPw = getServletConfig().getInitParameter("adminPw");
		
		PrintWriter out = response.getWriter();
		out.print("<p>adminId : "+ adminId + "</p>");
		out.print("<p>adminId : "+ adminPw + "</p>");
		
		String imgDir = getServletContext().getInitParameter("imgDir");
		String testServerIP = getServletContext().getInitParameter("testServerIP");
		out.print("<p>imgDir : "+ imgDir + "</p>");
		out.print("<p>testServerIP : "+ testServerIP + "</p>");
		
	}


	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		doGet(request, response);
	}

}

구동 결과 :

12-3 context attribute

xml 파일

<?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_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>lec08Pjt001</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <context-param>
  	<param-name>imgDir</param-name>
  	<param-value>/upload/img</param-value>
  </context-param>
  <context-param>
  	<param-name>testServerIP</param-name>
  	<param-value>127.0.0.1</param-value>
  </context-param>
  <servlet>
  	<servlet-name>servletEx</servlet-name>
  	<servlet-class>com.servlet.ServletEx</servlet-class>
  	<init-param>
  		<param-name>adminId</param-name>
  		<param-value>admin</param-value>
  	</init-param>
  	<init-param>
  		<param-name>adminPw</param-name>
  		<param-value>1234</param-value>
  	</init-param>
  </servlet>
  <servlet-mapping>
  	<servlet-name>servletEx</servlet-name>
  	<url-pattern>/se</url-pattern>
  </servlet-mapping>
</web-app>

첫번째 jsp파일

package com.servlet;

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 ServletEx
 */

public class ServletEx extends HttpServlet {

	
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String adminId = getServletConfig().getInitParameter("adminId");
		String adminPw = getServletConfig().getInitParameter("adminPw");
		
		PrintWriter out = response.getWriter();
		out.print("<p>adminId : "+ adminId + "</p>");
		out.print("<p>adminId : "+ adminPw + "</p>");
		
		String imgDir = getServletContext().getInitParameter("imgDir");
		String testServerIP = getServletContext().getInitParameter("testServerIP");
		out.print("<p>imgDir : "+ imgDir + "</p>");
		out.print("<p>testServerIP : "+ testServerIP + "</p>");
		
		getServletContext().setAttribute("connectedIP", "165.62.58.33");
		getServletContext().setAttribute("connectedUser", "gildong");
		
	}


	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		doGet(request, response);
	}

}

두번째 jsp파일

package com.servlet;

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;

@WebServlet("/seg")
public class ServletGet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
		String connectedIP = (String)getServletContext().getAttribute("connectedIP");
		String connectedUser = (String)getServletContext().getAttribute("connectedUser");
		
		PrintWriter out = response.getWriter();
		out.print("<p>connectedIP : "+ connectedIP + "</p>");
		out.print("<p>connectedUser : "+ connectedUser + "</p>");
	}

	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

서버 구동후 먼저 두번째 jsp에 접속하면 connectedIP와 connectedUser가 null로 표현되지만,

첫번째 jsp 방문 후 두번째 jsp에 접속하면 IP와 user가 정상적으로 보이는 것을 확인할 수 있다.

<- 첫 방문시

<- 첫번째 jsp파일 접근 후 재방문시

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9 JSP 스크립트 (0)	2020.03.19
5 Servlet 맵핑 (0)	2020.03.15

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개발기록

12 Servlet 데이터 공유 본문

12 Servlet 데이터 공유

12-1 servlet parameter

12-2 context parameter

12-3 context attribute

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