四個有用的過濾器（Filter）

參考：http://www.blogjava.net/fantasy/archive/2006/03/21/36593.html

一、使瀏覽器不緩存頁面的過濾器

import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
* 用於的使 Browser 不緩存頁面的過濾器
*/
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
{
}
}

二、檢測用戶是否登陸的過濾器

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;

/**
* 用於檢測用戶是否登陸的過濾器，如果未登錄，則重定向到指的登錄頁面<p>
* 配置參數<p>
* checkSessionKey 需檢查的在 Session 中保存的關鍵字<br/>
* redirectURL 如果用戶未登錄，則重定向到指定的頁面，URL 不包括 ContextPath<br/>
* notCheckURLList 不做檢查的URL 列表，以分號分開，並且 URL 中不包括 ContextPath<br/>
*/
public class CheckLoginFilter
implements Filter
{
     protected FilterConfig filterConfig = null;
    private String redirectURL = null;
     private List notCheckURLList = new ArrayList();
     private String sessionKey = null;

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());
    }
   }
}
}

 

<!-- /* Font Definitions */ @font-face {font-family:宋體; panose-1:2 1 6 0 3 1 1 1 1 1; mso-font-alt:SimSun; mso-font-charset:134; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:3 680460288 22 0 262145 0;} @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:1; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-520092929 1073786111 9 0 415 0;} @font-face {font-family:"/@宋體"; panose-1:2 1 6 0 3 1 1 1 1 1; mso-font-charset:134; mso-generic-font-family:auto; mso-font-pitch:variable; mso-font-signature:3 680460288 22 0 262145 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; text-align:justify; text-justify:inter-ideograph; mso-pagination:none; font-size:10.5pt; mso-bidi-font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:宋體; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-font-kerning:1.0pt;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} /* Page Definitions */ @page {mso-page-border-surround-header:no; mso-page-border-surround-footer:no;} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} -->

三、字符編碼的過濾器

import javax.servlet.*;
import java.io.IOException;

/**
* 用於設置 HTTP 請求字符編碼的過濾器，通過過濾器參數encoding 指明使用何種字符編碼, 用於處理Html Form 請求參數的中文問題
*/
public class CharacterEncodingFilter
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");

}
}

四、資源保護過濾器

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) {

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