一、防盗链图片的filter

public class ImageRedirectFilter implements Filter {

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);
  }
}
}

二、web.xml

<filter>
 <filter-name>imageRedirectFilter</filter-name>
 <filter-class>com.filter.ImageRedirectFilter</filter-class>
</filter>
<filter-mapping>
 <filter-name>imageRedirectFilter</filter-name>
 <url-pattern>/upload/images/*</url-pattern>
</filter-mapping>

原帖地址：http://blog.csdn.net/itm_hadf/article/details/7390180