驼峰转下划线

/**
 * 驼峰转下划线
 */
public static String humpToLine(String str) {
    Matcher matcher = humpPattern.matcher(str);
    StringBuffer sb = new StringBuffer();
    while (matcher.find()) {
        matcher.appendReplacement(sb, "_" + matcher.group(0).toLowerCase());
    }
    matcher.appendTail(sb);
    return sb.toString();
}