Java下划线字符串转驼峰字符串

/**
 * 下划线
 */
private static final char SEPARATOR = '_';

/**
 * 驼峰式命名法
 * 例如：user_name->userName
 */
public static String toCamelCase(String s) {
    if (s == null) {
        return null;
    }
    s = s.toLowerCase();
    StringBuilder sb = new StringBuilder(s.length());
    boolean upperCase = false;
    for (int i = 0; i < s.length(); i++) {
        char c = s.charAt(i);

        if (c == SEPARATOR) {
            upperCase = true;
        } else if (upperCase) {
            sb.append(Character.toUpperCase(c));
            upperCase = false;
        } else {
            sb.append(c);
        }
    }
    return sb.toString();
}