org.apache.http.conn.util.DnsUtils Maven / Gradle / Ivy
/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* .
*
*/
package org.apache.http.conn.util;
/**
* A collection of utilities relating to Domain Name System.
*
* @since 4.5
*/
public class DnsUtils {
private DnsUtils() {
}
private static boolean isUpper(final char c) {
return c >= 'A' && c <= 'Z';
}
public static String normalize(final String s) {
if (s == null) {
return null;
}
int pos = 0;
int remaining = s.length();
while (remaining > 0) {
if (isUpper(s.charAt(pos))) {
break;
}
pos++;
remaining--;
}
if (remaining > 0) {
final StringBuilder buf = new StringBuilder(s.length());
buf.append(s, 0, pos);
while (remaining > 0) {
final char c = s.charAt(pos);
if (isUpper(c)) {
buf.append((char) (c + ('a' - 'A')));
} else {
buf.append(c);
}
pos++;
remaining--;
}
return buf.toString();
} else {
return s;
}
}
}