Apache使用.htaccess防盗链

.htaccess防盗链规则代码：

RewriteEngine on
RewriteCond %{ HTTP_REFERER }!4$
RewriteCond %{ HTTP_REFERER}
！Ahttp://(www.)?yourdomain.com/.*$ [NCI
RewriteRule.(gif &line;jpg)$ http://
www.yourdomain.com/替代图片文件名[RL]