필터 필터 클래식 응용 프로그램

1. 브라우저가 페이지를 캐시하지 않도록 하는 필터
import javax.servlet.*;import javax.servlet.http.HttpServletResponse;import java.io.IOException;
/*** 브라우저에서 페이지를 캐시하지 않도록 하는 필터 */public class ForceNoCacheFilter implements Filter {
 public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {  ((HttpServletResponse) response).setHeader("Cache-Control","no-cache");  ((HttpServletResponse) response).setHeader("Pragma","no-cache");  ((HttpServletResponse) response).setDateHeader ("Expires", -1);  filterChain.doFilter(request, response); }
 public void destroy() { }
    public void init(FilterConfig filterConfig) throws ServletException { }}
2. 사용자가 로그인했는지 확인하는 필터
import javax.servlet.*;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import java.util.List;import java.util.ArrayList;import java.util.StringTokenizer;import java.io.IOException;
/*** 사용자가 로그인했는지 확인하는 데 사용되는 필터입니다. 로그인하지 않으면 지정한 로그인 페이지로 리디렉션합니다. Context Path
* notCheckURLlist가 검사하지 않는 URL 목록을 포함하지 않고 구분하여 지정한 페이지로 리디렉션합니다.또한 URL에는 Context Path
*/public class CheckLoginFilter implements Filter {protected FilterConfig filterConfig = null;private String redirectURL = null;private List notCheckURLlist = new Array List();private String sessionKey =null이 포함되지 않습니다.
 public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {  HttpServletRequest request = (HttpServletRequest) servletRequest;  HttpServletResponse response = (HttpServletResponse) servletResponse;
   HttpSession session = request.getSession();  if(sessionKey == null)  {   filterChain.doFilter(request, response);   return;  }  if((!checkRequestURIIntNotFilterList(request)) && session.getAttribute(sessionKey) == null)  {   response.sendRedirect(request.getContextPath() + redirectURL);   return;  }  filterChain.doFilter(servletRequest, servletResponse); }
 public void destroy() {  notCheckURLList.clear(); }
 private boolean checkRequestURIIntNotFilterList(HttpServletRequest request) {  String uri = request.getServletPath() + (request.getPathInfo() == null ? "": request.getPathInfo());  return notCheckURLList.contains(uri); }
 public void init(FilterConfig filterConfig) throws ServletException {  this.filterConfig = filterConfig;  redirectURL = filterConfig.getInitParameter("redirectURL");  sessionKey = filterConfig.getInitParameter("checkSessionKey");
  String notCheckURLListStr = filterConfig.getInitParameter("notCheckURLList");
  if(notCheckURLListStr != null)  {   StringTokenizer st = new StringTokenizer(notCheckURLListStr, ";");   notCheckURLList.clear();   while(st.hasMoreTokens())   {    notCheckURLList.add(st.nextToken());   }  } }}
3. 문자 인코딩 필터
import javax.servlet.*;import java.io.IOException;
/*** HTTP 요청 문자 인코딩을 설정하는 데 사용되는 필터입니다. 필터 매개 변수 인코딩을 통해 어떤 문자 인코딩을 사용할지, Html Form 요청 매개 변수를 처리하는 데 사용되는 중국어 문제 */public class CharacterEncoding Filter implements Filter {protected FilterConfig filterConfig =null;protected String encoding =";
 public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {        if(encoding != null)         servletRequest.setCharacterEncoding(encoding);        filterChain.doFilter(servletRequest, servletResponse); }
 public void destroy() {  filterConfig = null;  encoding = null; }
    public void init(FilterConfig filterConfig) throws ServletException {         this.filterConfig = filterConfig;        this.encoding = filterConfig.getInitParameter("encoding");
 }}
4. 자원 보호 필터

package catalog.view.util;

import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.util.Iterator;
import java.util.Set;
import java.util.HashSet;
//
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * This Filter class handle the security of the application.
 * 

 * It should be configured inside the web.xml.
 * 
 * @author Derek Y. Shen
 */
public class SecurityFilter implements Filter {
 //the login page uri
 private static final String LOGIN_PAGE_URI = "login.jsf";
 
 //the logger object
 private Log logger = LogFactory.getLog(this.getClass());
 
 //a set of restricted resources
 private Set restrictedResources;
 
 /**
 * Initializes the Filter.
 */
 public void init(FilterConfig filterConfig) throws ServletException {
 this.restrictedResources = new HashSet();
 this.restrictedResources.add("/createProduct.jsf");
 this.restrictedResources.add("/editProduct.jsf");
 this.restrictedResources.add("/productList.jsf");
 }
 
 /**
 * Standard doFilter object.
 */
 public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
 throws IOException, ServletException {
 this.logger.debug("doFilter");
 
 String contextPath = ((HttpServletRequest)req).getContextPath();
 String requestUri = ((HttpServletRequest)req).getRequestURI();
 
 this.logger.debug("contextPath = " + contextPath);
 this.logger.debug("requestUri = " + requestUri);
 
 if (this.contains(requestUri, contextPath) && !this.authorize((HttpServletRequest)req)) {
 this.logger.debug("authorization failed");
 ((HttpServletRequest)req).getRequestDispatcher(LOGIN_PAGE_URI).forward(req, res);
 }
 else {
 this.logger.debug("authorization succeeded");
 chain.doFilter(req, res);
 }
 }
 
 public void destroy() {} 
 
 private boolean contains(String value, String contextPath) {
 Iterator ite = this.restrictedResources.iterator();
 
 while (ite.hasNext()) {
 String restrictedResource = (String)ite.next();
 
 if ((contextPath + restrictedResource).equalsIgnoreCase(value)) {
 return true;
 }
 }
 
 return false;
 }
 
 private boolean authorize(HttpServletRequest req) {

 // 
 /* UserBean user = (UserBean)req.getSession().getAttribute(BeanNames.USER_BEAN);
 
 if (user != null && user.getLoggedIn()) {
 //user logged in
 return true;
 }
 else {
 return false;
 }*/
 }
}