filter图片防盗链

        防盗链Filter实现这样一种效果，如果其他网站通过链接引用本网站的图片资源，将会显示一个错误页面。只有本站内的网页引用时，图片才会正常显示，即在图片显示之前对request进行验证，看客户请求是否来自本网站内，代码如下：@WebFilter(filterName = "ImageFilter")
public class ImageFilter implements Filter {
public void destroy() {
}

public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
HttpServletRequest request = (HttpServletRequest)req;
HttpServletResponse response = (HttpServletResponse)resp;
String referer = request.getHeader("referer");
//如来自其他网站的请求
if(referer == null||!referer.contains(request.getServerName())){
request.getRequestDispatcher("/error/error.jsp").forward(request,response);
}else{
chain.doFilter(request, response);
}
}

public void init(FilterConfig config) throws ServletException {

}

}        改Filter从request信息头中获取请求来自何方，Filter的配置代码如下：<filter>
<filter-name>imgageFilter</filter-name>
<filter-class>filter.ImageFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>imgageFilter</filter-name>
<url-pattern>/images/*</url-pattern>
</filter-mapping>        改Filter配置表明对"/images/"下面的所有资源进行防盗链过滤处理。运行效果如下：
正常链接：



非正常链接