过滤样式文件，防止被非法下载

/**
 *  过滤样式文件，防止被非法下载
 * (通过抓包工具(如:HttpWatch)可以破解该方法)
 * @author RuiLin.Xie - xKF24276
 *
 */
public class StyleFilter implements Filter
{

	public void destroy()
	{
		
	}

	/**
	 *  过滤样式文件，防止被非法下载
	 * (通过抓包工具(如:HttpWatch)可以破解该方法)
	 */
	public void doFilter(ServletRequest arg0, ServletResponse arg1,
			FilterChain arg2) throws IOException, ServletException
	{
		HttpServletRequest request = (HttpServletRequest)arg0;
		
		//获得上一访问的地址
		String referer = request.getHeader("referer");
		
		/** Cookie验证 **/
		Cookie[] cookies = request.getCookies();
		String v = null;
		for(int i = 0; cookies != null && i < cookies.length; i++)
		{
			String n = cookies[i].getName();
			if(n.equals("FURL"))
			{
				//读出URL并解密
				v = cookies[i].getValue();
			}
			else
				continue;
		}
		Object oFurl = request.getSession().getAttribute("FURL");
		//如果值不一致，说明错误，直接返回空
		if(v == null || oFurl == null || !v.equals(oFurl.toString()))
		{
			System.out.println("非法下载,已被拦截");
			return;
		}
		/** Cookie验证结束 **/
		
		//如果是从本站访问，那么可以下载，否则不可下载
		if(referer != null && referer.startsWith("http://localhost:8080/"))
		{
			//禁止IE缓存，否则还是可以下载
			HttpServletResponse response = (HttpServletResponse)arg1;
			response.setHeader("Cache-Control","no-cache"); //HTTP 1.1
			response.setHeader("Pragma","no-cache"); //HTTP 1.0
			response.setDateHeader ("Expires", 0); //prevents caching at the proxy server
			
			arg2.doFilter(arg0, arg1);
		}
		else
		{
			System.out.println("非法下载,已被拦截");
		}
	}

	public void init(FilterConfig arg0) throws ServletException
	{
		
	}

}