正则表达式驼峰标示转下划线

humpToUnderline

/**
* 驼峰转下划线
* @param humpString
* created by hbd 20160722
* @return
*/
public String humpToUnderline(String humpString) {
if(BlankUtil.isEmpty(humpString)) return "";
String regexStr = "[A-Z]";
Matcher matcher = Pattern.compile(regexStr).matcher(humpString);
StringBuffer sb = new StringBuffer();
while (matcher.find()) {
String g = matcher.group();
matcher.appendReplacement(sb, "_" + g.toLowerCase());
}
matcher.appendTail(sb);
if (sb.charAt(0) == '_') {
sb.delete(0, 1);
}
return sb.toString();
}