//ArgsIsValidFilter .java過濾器程式碼清單：
package com.hety.uitl;

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

public class ArgsIsValidFilter implements Filter {

private static Log log = LogFactory.getLog(ArgsIsValidFilter.class);

public void destroy() {

}

@SuppressWarnings("unchecked")
public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2) throws IOException, ServletException {
   HttpServletRequest request = (HttpServletRequest) arg0;
   HttpServletResponse response = (HttpServletResponse) arg1;
   String servername_str = request.getServerName();
   String currentURI = request.getRequestURI();
   Enumeration headerValues = request.getHeaders("Referer");
   String tmpHeaderValue = "";
   boolean isValid = true;
   //指定需要跳過攔截的頁面地址，如果需要新增，可直接在陣列中新增。
   //“建議”
   String [] ignoreURIS={"/back/",
                  "/Info.jsp",
                  "/pzxx.jsp"
                  };
   while (headerValues.hasMoreElements()) {
    // 得到完整的路徑：如“http://www.domain.com.cn:8023/front/zwgk/zwgk.jsp?id=1283”
    tmpHeaderValue = (String) headerValues.nextElement();
   }

   if(log.isInfoEnabled()){
    log.info(" 獲得的引數url為: " + tmpHeaderValue );
    log.info(" 系統取得的url為："+ currentURI);
   }

   if ("".equals(tmpHeaderValue)) {
    isValid = false;
    if(log.isInfoEnabled()){
     log.info(" 獲得的引數url為: empty");
     log.info(" 系統取得的url為："+ currentURI);
     log.info("系統提示：請求可能來自外域！"); 
    }

   } else {
    if(log.isInfoEnabled()){
     log.info("獲得的引數長度為:"+tmpHeaderValue.length());
    }
    tmpHeaderValue = tmpHeaderValue.toLowerCase();
    servername_str = servername_str.toLowerCase();

    int len = 0;
    if (tmpHeaderValue.startsWith("https://")) {
     len = 8;
    } else if (tmpHeaderValue.startsWith("http://")) {
     len = 7;
    }

    if(log.isInfoEnabled()){
     log.info("擷取前的字串為：" + tmpHeaderValue );
     log.info( "從第 " + len + " 位開始擷取，擷取長度為：" + servername_str.length());
    }
    String tmp = tmpHeaderValue.substring(len, servername_str.length() + len);
    if(log.isInfoEnabled()){
     log.info("擷取後的字串為：" + tmp);
    }
    if (tmp.length() < servername_str.length()) { // 長度不夠
     isValid = false;
     if(log.isInfoEnabled()){
      log.info("擷取後的字串長度不夠,請求可能來自外域！");
     }
    } else if (!tmp.equals(servername_str)) {// 比較字串（主機名稱）是否相同
     isValid = false;
     if(log.isInfoEnabled()){
      log.info("域名匹配失敗，請求來自外域！");
     }
    }
   }
  
  
   // 跳過指定需要攔截的頁面地址
   for (String ignoreURI : ignoreURIS) {
    if(currentURI.contains(ignoreURI)){
     isValid=true;
     if(log.isInfoEnabled()){
      log.info("系統已跳過檢查以下url："+currentURI);
     }
    }
   }

   if (!isValid) {
   
    if(log.isInfoEnabled()){
     log.info("系統提示資訊：URL為跨域請求，即將重定向到首頁。 ");
    }
    response.sendRedirect("/index.html");
   } else {
    arg2.doFilter(arg0, arg1);
   }
}

public void init(FilterConfig arg0) throws ServletException {

}

}