76 lines
2.5 KiB
Java
76 lines
2.5 KiB
Java
/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache license, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the license for the specific language governing permissions and
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* limitations under the license.
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*/
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package org.apache.commons.text.lookup;
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import java.net.InetAddress;
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import java.net.UnknownHostException;
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/**
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* Looks up keys related to the local host: host name, canonical host name, host address.
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* <p>
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* The lookup keys are:
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* </p>
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* <ul>
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* <li><b>name</b>: for the local host name, for example {@code EXAMPLE}.</li>
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* <li><b>canonical-name</b>: for the local canonical host name, for example {@code EXAMPLE.apache.org}.</li>
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* <li><b>address</b>: for the local host address, for example {@code 192.168.56.1}.</li>
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* </ul>
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*
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* @since 1.3
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*/
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final class LocalHostStringLookup extends AbstractStringLookup {
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/**
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* Defines the singleton for this class.
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*/
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static final LocalHostStringLookup INSTANCE = new LocalHostStringLookup();
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/**
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* No need to build instances for now.
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*/
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private LocalHostStringLookup() {
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// empty
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}
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/**
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* Looks up the value of a local host key.
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*
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* @param key the key to be looked up, may be null.
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* @return The value of the environment variable.
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*/
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@Override
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public String lookup(final String key) {
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if (key == null) {
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return null;
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}
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try {
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switch (key) {
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case InetAddressKeys.KEY_NAME:
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return InetAddress.getLocalHost().getHostName();
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case InetAddressKeys.KEY_CANONICAL_NAME:
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return InetAddress.getLocalHost().getCanonicalHostName();
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case InetAddressKeys.KEY_ADDRESS:
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return InetAddress.getLocalHost().getHostAddress();
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default:
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throw new IllegalArgumentException(key);
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}
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} catch (final UnknownHostException e) {
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return null;
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}
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}
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}
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