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

/**
 * 用於的使 Browser 不快取頁面的過濾器
 */
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
 {
 }
}

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;

/**
 * 用於檢測使用者是否登陸的過濾器，如果未登入，則重定向到指的登入頁面<p>
 * 配置引數<p>
 * checkSessionKey 需檢查的在 Session 中儲存的關鍵字<br/>
 * redirectURL 如果使用者未登入，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());
   }
  }
 }
}

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

/**
 * 用於設定 HTTP 請求字元編碼的過濾器，通過過濾器引數encoding指明使用何種字元編碼,用於處理Html Form請求引數的中文問題
 */
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");

 }
}