的组合
SetEnvIf以及
Header可能做的伎俩：
# Image, CSS and Javascript requests normally contain the Referer header# which tells apache which page is requesting the resource# Use SetEnvIf directive to set a flag for internal usesSetEnvIf Referer preview.jsp force_no_cache# Header directive optionally accepts env= argument# If present, the directive is fired if the flag is setHeader unset ETag env=force_no_cache# repeat for other headers
