/**
* 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.
*/
package org.apache.tajo.net;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class CachedDNSResolver {
private static Map<String, String> hostNameToIPAddrMap
= new ConcurrentHashMap<String, String>();
private static CachedDNSResolver instance;
static {
instance = new CachedDNSResolver();
}
public static String resolve(String hostName) {
if (hostNameToIPAddrMap.containsKey(hostName)) {
return hostNameToIPAddrMap.get(hostName);
}
String ipAddress = null;
try {
ipAddress = InetAddress.getByName(hostName).getHostAddress();
} catch (UnknownHostException e) {
e.printStackTrace();
}
hostNameToIPAddrMap.put(hostName, ipAddress);
return ipAddress;
}
public static String [] resolve(String [] hostNames) {
if (hostNames == null) {
return null;
}
String [] resolved = new String[hostNames.length];
for (int i = 0; i < hostNames.length; i++) {
resolved[i] = resolve(hostNames[i]);
}
return resolved;
}
}