一个小小的防盗链图片的filter

public class ImageRedirectFilter implements Filter {

?public void init(FilterConfig config) throws ServletException {
?}

?public void doFilter(ServletRequest req, ServletResponse res,
???FilterChain chain) throws IOException, ServletException {

??HttpServletRequest request = (HttpServletRequest) req;
??HttpServletResponse response = (HttpServletResponse) res;

??// 禁止缓存
??response.setHeader("Cache-Control", "no-store");
??response.setHeader("Pragrma", "no-cache");
??response.setDateHeader("Expires", 0);

??// 链接来源地址
??String referer = request.getHeader("referer");
??System.out.println("refer is"+referer);

??if (referer == null || !referer.contains(request.getServerName())) {

???/**
??? * 如果 链接地址来自其他网站，则返回错误图片
??? */
???request.getRequestDispatcher("/error.gif").forward(request,
?????response);

??} else {

???/**
??? * 图片正常显示
??? */
???chain.doFilter(request, response);
??}

?}

?public void destroy() {
?}
}

?

?

web.xml:

<filter-mapping>
??<filter-name>imageRedirectFilter</filter-name>
????<url-pattern>/upload/images/*</url-pattern>
?</filter-mapping>

<script type="text/javascript"></script>