001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.wicket.util.collections;
018
019import java.io.Serializable;
020import java.net.URL;
021import java.util.Comparator;
022
023/**
024 * A comparator of URL instances.
025 *
026 * Comparing URLs with their implementation of #equals() is
027 * bad because it may cause problems like DNS resolving, or other
028 * slow checks. This comparator uses the external form of an URL
029 * to make a simple comparison of two Strings.
030 *
031 * @since 1.5.6
032 */
033public class UrlExternalFormComparator implements Comparator<URL>, Serializable
034{
035        private static final long serialVersionUID = 1L;
036
037        @Override
038        public int compare(URL url1, URL url2)
039        {
040                return url1.toExternalForm().compareTo(url2.toExternalForm());
041        }
042}