利用 filter 机制给静态资源 url 加上时间戳，来防止js和css文件的缓存问题

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=";