1 /* 2 * ==================================================================== 3 * Licensed to the Apache Software Foundation (ASF) under one 4 * or more contributor license agreements. See the NOTICE file 5 * distributed with this work for additional information 6 * regarding copyright ownership. The ASF licenses this file 7 * to you under the Apache License, Version 2.0 (the 8 * "License"); you may not use this file except in compliance 9 * with the License. You may obtain a copy of the License at 10 * 11 * http://www.apache.org/licenses/LICENSE-2.0 12 * 13 * Unless required by applicable law or agreed to in writing, 14 * software distributed under the License is distributed on an 15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 16 * KIND, either express or implied. See the License for the 17 * specific language governing permissions and limitations 18 * under the License. 19 * ==================================================================== 20 * 21 * This software consists of voluntary contributions made by many 22 * individuals on behalf of the Apache Software Foundation. For more 23 * information on the Apache Software Foundation, please see 24 * <http://www.apache.org/>. 25 * 26 */ 27 package org.apache.hc.client5.http; 28 29 import java.net.InetAddress; 30 import java.net.UnknownHostException; 31 32 import org.apache.hc.core5.annotation.Contract; 33 import org.apache.hc.core5.annotation.ThreadingBehavior; 34 35 /** 36 * Users may implement this interface to override the normal DNS lookup offered 37 * by the OS. 38 * 39 * @since 4.2 40 */ 41 @Contract(threading = ThreadingBehavior.STATELESS) 42 public interface DnsResolver { 43 44 /** 45 * Returns the IP address for the specified host name, or null if the given 46 * host is not recognized or the associated IP address cannot be used to 47 * build an InetAddress instance. 48 * 49 * @see InetAddress 50 * 51 * @param host 52 * The host name to be resolved by this resolver. 53 * @return The IP address associated to the given host name, or null if the 54 * host name is not known by the implementation class. 55 */ 56 InetAddress[] resolve(String host) throws UnknownHostException; 57 58 /** 59 * Gets the fully qualified domain name for given host name. 60 * @since 5.0 61 */ 62 String resolveCanonicalHostname(String host) throws UnknownHostException; 63 64 }