JSP MVC 모델 기본 설명 : 모델 2 구조를 이용한 MVC 패턴 구현
[출처] http://dawnisthm.tistory.com/152
< 모델 2 구조를 이용한 MVC 패턴 구현 >
1. 모델 2 구조의 구현 방법 : 기본 MVC 패턴 구현 기법
[SimpleController.java]
| package soldesk.mvc;
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 SimpleController extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); }
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { processRequest(request, response); }
private void processRequest(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException { // 2단계, 요청 파악 // request 객체로부터 사용자의 요청을 파악하는 코드 String type = request.getParameter("type");
// 3단계, 요청한 기능을 수행한다. // 사용자에 요청에 따라 알맞은 코드 Object resultObject = null; if (type == null || type.equals("greeting")) { resultObject = "안녕하세요."; } else if (type.equals("date")) { resultObject = new java.util.Date(); } else { resultObject = "Invalid Type"; }
// 4단계, request나 session에 처리 결과를 저장 request.setAttribute("result", resultObject);
// 5단계, RequestDispatcher를 사용하여 알맞은 뷰로 포워딩 RequestDispatcher dispatcher = request.getRequestDispatcher("/simpleView.jsp"); dispatcher.forward(request, response); } } |
[simpleView.jsp]
<%@ page language="java" contentType="text/html; charset=EUC-KR"%> <html> <head> <title>뷰</title> </head> <body> // 컨트롤러가 전달한 값을 읽어옴. 결과 : <%= request.getAttribute("result")%> </body> </html> |
[WEB-INF\web.xml]에 추가
| <servlet> <servlet-name>SimpleController</servlet-name> <servlet-class>soldesk.mvc.SimpleController</servlet-class>
<servlet-mapping> <servlet-name>SimpleController</servlet-name> <url-pattern>/simple</url-pattern> </servlet-mapping> |
그리고 SimpleController.java를 실행시켜 보자.(JSP 페이지 구동시키는 것 아님을 주의!!)
2. 커맨드 패턴 기반의 코드
컨트롤러 서블릿이 사용자가 어떤 기능을 요청했는지 분석하기 위해 가장 일반적으로 사용하는 방법은 명령어를 사용하는 것이다.
- 특정 이름의 파라미터에 명령어 정보를 전달한다.
- 요청 URI 자체를 명령어로 사용한다.
<커맨드 패턴을 이용한 명령어 처리기의 분리>
| String commend = request.getParameter("cmd"); CommandHandler handler = null;
if(command == null){ handler = new NullHandler(); }else if{command.equals("BoardList")){ handler = new BoardListHandler(); }else if(command.equals("BoardWriteForm"){ handler = new BoardWriteFormHandler(); } String viewPage = handler.process(request, response);
RequestDispatcher dispatcher = request.getRequestDispatcher(viewPage); dispatcher.forward(request, response); |
명령어를 처리하는 핸들러 클래스들은 CommandHandler 인터페이스를 구현하면 된다.
핸들러 클래스에서 처리해야 할 작업 |
public class SimeHandler implements CommandHandler{ public String process(HttpServletRequest request, HttpServletResponse response) throws Throwable{ // 1. 명령어과 관련된 비즈니스 로직 처리 // 2. 뷰 페이지에서 사용할 정보 저장 request.setAttribute("someValue", value); // 3. 뷰 페이지의 URI 리턴 return "/view/someView.jsp"; } } |
3. 설정 파일에 커맨드와 클래스의 관계 명시하기
: <명령어, 명령어 핸들러 클래스>의 매핑 정보를 설정 파일에 저장
BoardList = soldesk.command.BoardListHandler |
BoardWriteForm = soldesk.command.BoardWriteFormHandler |
[ControllerUsingFile.java]
| package soldesk.mvc.controller;
import java.io.FileInputStream; import java.io.IOException; import java.net.URL; import java.util.Iterator; import java.util.Map; import java.util.Properties;
import javax.servlet.RequestDispatcher; import javax.servlet.ServletConfig; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;
import soldesk.mvc.command.CommandHandler; import soldesk.mvc.command.NullHandler;
public class ControllerUsingFile extends HttpServlet {
// <커맨드, 핸들러 인스턴스> 매핑 정보 저장 private Map commandHandlerMap = new java.util.HashMap();
public void init(ServletConfig config) throws ServletException { String configFile = config.getInitParameter("configFile"); Properties prop = new Properties(); FileInputStream fis = null; try { String configFilePath = config.getServletContext().getRealPath( configFile); fis = new FileInputStream(configFilePath); prop.load(fis); } catch (IOException e) { throw new ServletException(e); } finally { if (fis != null) try { fis.close(); } catch (IOException ex) { } } Iterator keyIter = prop.keySet().iterator(); while (keyIter.hasNext()) { String command = (String) keyIter.next(); String handlerClassName = prop.getProperty(command); try { Class handlerClass = Class.forName(handlerClassName); Object handlerInstance = handlerClass.newInstance(); commandHandlerMap.put(command, handlerInstance); } catch (ClassNotFoundException e) { throw new ServletException(e); } catch (InstantiationException e) { throw new ServletException(e); } catch (IllegalAccessException e) { throw new ServletException(e); } } }
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { process(request, response); }
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { process(request, response); }
private void process(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String command = request.getParameter("cmd"); CommandHandler handler = (CommandHandler) commandHandlerMap .get(command); if (handler == null) { handler = new NullHandler(); } String viewPage = null; try { viewPage = handler.process(request, response); } catch (Throwable e) { throw new ServletException(e); }
RequestDispatcher dispatcher = request.getRequestDispatcher(viewPage); dispatcher.forward(request, response); } } |
[WEB-INF\web.xml]에 추가
| <servlet> <servlet-name>ControllerUsingFile</servlet-name> <servlet-class>soldesk.mvc.controller.ControllerUsingFile</servlet-class> <init-param> <param-name>configFile</param-name> <param-value>/WEB-INF/commandHandler.properties</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>ControllerUsingFile</servlet-name> <url-pattern>/controllerUsingFile</url-pattern> </servlet-mapping> |
[commandHandler.properties]
hello = soldesk.mvc.command.HelloHandler
[CommandHandler.java]
| package soldesk.mvc.controller;
import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;
import soldesk.mvc.command.CommandHandler;
public class CommandHandler { public String process(HttpServletRequest request, HttpServletResponse response) throws Throwable{ return.setAttribute("hello", "안녕하세요!"); return "/mvc/view/hello.jsp"; } } |
[HelloHandler.java]
| package soldesk.mvc.command;
import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;
import soldesk.mvc.command.CommandHandler;
public class HelloHandler implements CommandHandler {
public String process(HttpServletRequest request, HttpServletResponse response) throws Throwable { request.setAttribute("hello", "안녕하세요!"); return "/mvc/view/hello.jsp"; } } |
[NullHandler.java]
| package soldesk.mvc.command;
import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;
public class NullHandler implements CommandHandler {
@Override public String process(HttpServletRequest request, HttpServletResponse response) throws Throwable { return "/mvc/view/nullCommand.jsp"; } } |
[hello.jsp]
| <%@ page contentType = "text/html; charset=euc-kr" %> <html> <head><title>Hello</title></head> <body>
<%= request.getAttribute("hello") %>
</body> </html> |
[nullCommand.jsp]
| <%@ page contentType="text/html; charset=euc-kr" %> <html> <head><title>에러</title></head> <body>
잘못된 요청입니다.
</body> </html> |
4. 요청 URI를 명령어로 사용하기
: 명령어 기반의 파라미터는 컨트롤러의 URL이 사용자에게 노출된다는 단점이 있다.
따라서 URL의 일부를 명령어로 사용하여 이런 문제를 방지할 수 있다.
- URI 를 명령어로 사용하기 위해서는 컨트롤러 서블릿의 process()메서드에서 request.getParameter("cmd") 대신
String command = request.getRequestURI(); if(command.indexOF(request.getContextPath()) == 0){
command = command.subString(request.getContextPath().length());
}
를 사용하면 된다.
[ControllerUsingURI.java]
| package soldesk.mvc.controller;
import java.io.FileInputStream; import java.io.IOException; import java.net.URL; import java.util.Iterator; import java.util.Map; import java.util.Properties;
import javax.servlet.RequestDispatcher; import javax.servlet.ServletConfig; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;
import soldesk.mvc.command.CommandHandler; import soldesk.mvc.command.NullHandler;
public class ControllerUsingURI extends HttpServlet {
// <커맨드, 핸들러인스턴스> 매핑 정보 저장 private Map commandHandlerMap = new java.util.HashMap();
public void init(ServletConfig config) throws ServletException { String configFile = config.getInitParameter("configFile2"); Properties prop = new Properties(); FileInputStream fis = null; try { String configFilePath = config.getServletContext().getRealPath( configFile); fis = new FileInputStream(configFilePath); prop.load(fis); } catch (IOException e) { throw new ServletException(e); } finally { if (fis != null) try { fis.close(); } catch (IOException ex) { } } Iterator keyIter = prop.keySet().iterator(); while (keyIter.hasNext()) { String command = (String) keyIter.next(); String handlerClassName = prop.getProperty(command); try { Class handlerClass = Class.forName(handlerClassName); Object handlerInstance = handlerClass.newInstance(); commandHandlerMap.put(command, handlerInstance); } catch (ClassNotFoundException e) { throw new ServletException(e); } catch (InstantiationException e) { throw new ServletException(e); } catch (IllegalAccessException e) { throw new ServletException(e); } } }
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { process(request, response); }
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { process(request, response); }
private void process(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String command = request.getRequestURI(); // /soldesk/hello.do if (command.indexOf(request.getContextPath()) == 0) { // /soldesk command = command.substring(request.getContextPath().length()); // /hello.do } CommandHandler handler = (CommandHandler) commandHandlerMap.get(command); if (handler == null) { handler = new NullHandler(); } String viewPage = null; try { viewPage = handler.process(request, response); } catch (Throwable e) { throw new ServletException(e); }
RequestDispatcher dispatcher = request.getRequestDispatcher(viewPage); dispatcher.forward(request, response); } } |
[web.xml]
| <servlet> <servlet-name>ControllerUsingURI</servlet-name> <servlet-class>soldesk.mvc.controller.ControllerUsingURI</servlet-class> <init-param> <param-name>configFile2</param-name> <param-value> /WEB-INF/commandHandlerURI.properties </param-value> </init-param> </servlet>
<servlet-mapping> <servlet-name>ControllerUsingURI</servlet-name> <url-pattern>*.do</url-pattern> </servlet-mapping> |
[commandHandlerURI.properties]
/hello.do=soldesk.mvc.command.HelloHandler
'Computer Science' 카테고리의 다른 글
| Eclipse, ANT, 그리고 EJB (java) 개발환경 (1) | 2012.06.06 |
|---|---|
| JAVA WEB EJB 엔터프라이즈 자바 빈즈 기초 (0) | 2012.06.06 |
| Xcode4로 시작하는 아이폰 프로그래밍 [Section3] (0) | 2012.06.05 |
| Bigtable, Blobstore 및 Google Storage를 사용하는 GAE 스토리지 (0) | 2012.05.21 |
| 클라우드 시대의 SW 기회와 위협 (0) | 2012.05.21 |