利用 filter 机制 给 静态资源 url 加上时间戳，来防止js和css文件的缓存，利于开发调试

public class WeiXinFilter implements Filter{
	private static Logger logger = LoggerFactory.getLogger(WeiXinFilter.class);
	public void init(FilterConfig fConfig) throws ServletException {}
	public void destroy() {}

	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
		HttpServletRequest req = (HttpServletRequest)request;
		HttpServletResponse resp = (HttpServletResponse)response;
		
		String requestURL = req.getRequestURL().toString();
		String queryStr = req.getQueryString();
		
		// add timestamp to static resource, to avoid cache
		if(requestURL != null && (requestURL.endsWith(".js") || requestURL.endsWith(".css"))){	// static resource
			String newURL = null;
			if(StringUtils.isNotBlank(queryStr) && queryStr.trim().indexOf(ParameterConfig.STATIC_TAIL) == -1){
				newURL = requestURL + "?" + queryStr + "&" + ParameterConfig.STATIC_TAIL + new Date().getTime();
				resp.sendRedirect(newURL);
//				req.getRequestDispatcher(newURL).forward(request, response);
				return;
			}
			if(StringUtils.isBlank(queryStr)){
				newURL = requestURL + "?" + ParameterConfig.STATIC_TAIL + new Date().getTime();
				resp.sendRedirect(newURL);
//				req.getRequestDispatcher(newURL).forward(request, response);
				return;
			}
			
			try{
				chain.doFilter(request, response);
			}catch(Exception e){
				logger.error(e.toString());
			}
			return;
		}

public class ParameterConfig 
{
	
	/** 静态资源 为防止缓存，加上时间戳标志 */
	public static final String STATIC_TAIL = "__oawx_t=";