function U($url='',$vars='',$suffix=true,$domain=false) {
if($suffix) {
$suffix = $suffix===true?C('URL_HTML_SUFFIX'):$suffix;
if($pos = strpos($suffix, '|')){
$suffix = substr($suffix, 0, $pos);
}
if($suffix && '/' != substr($url,-1)){
$url .= '.'.ltrim($suffix,'.');
}
}
修改为：
thinkphp/conf/convention.php
SHOW_URL_HTML_SUFFIX = true;

if($suffix && C('SHOW_URL_HTML_SUFFIX')) {
$suffix = $suffix===true?C('URL_HTML_SUFFIX'):$suffix;
if($pos = strpos($suffix, '|')){
$suffix = substr($suffix, 0, $pos);
}
if($suffix && '/' != substr($url,-1)){
$url .= '.'.ltrim($suffix,'.');
}
}