| 1 | /** |
| 2 | * Licensed to jclouds, Inc. (jclouds) under one or more |
| 3 | * contributor license agreements. See the NOTICE file |
| 4 | * distributed with this work for additional information |
| 5 | * regarding copyright ownership. jclouds licenses this file |
| 6 | * to you under the Apache License, Version 2.0 (the |
| 7 | * "License"); you may not use this file except in compliance |
| 8 | * with the License. You may obtain a copy of the License at |
| 9 | * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | * |
| 12 | * Unless required by applicable law or agreed to in writing, |
| 13 | * software distributed under the License is distributed on an |
| 14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| 15 | * KIND, either express or implied. See the License for the |
| 16 | * specific language governing permissions and limitations |
| 17 | * under the License. |
| 18 | */ |
| 19 | package org.jclouds.config; |
| 20 | |
| 21 | import static com.google.common.base.Preconditions.checkNotNull; |
| 22 | |
| 23 | import javax.inject.Inject; |
| 24 | import javax.inject.Singleton; |
| 25 | |
| 26 | import com.google.common.base.Function; |
| 27 | import com.google.inject.ConfigurationException; |
| 28 | import com.google.inject.Injector; |
| 29 | import com.google.inject.Key; |
| 30 | import com.google.inject.name.Names; |
| 31 | |
| 32 | /** |
| 33 | * |
| 34 | * @author Adrian Cole |
| 35 | */ |
| 36 | @Singleton |
| 37 | public class ValueOfConfigurationKeyOrNull implements Function<String, String> { |
| 38 | protected final Injector injector; |
| 39 | |
| 40 | @Inject |
| 41 | public ValueOfConfigurationKeyOrNull(Injector injector) { |
| 42 | this.injector = checkNotNull(injector, "injector"); |
| 43 | } |
| 44 | |
| 45 | @Override |
| 46 | public String apply(String configurationKey) { |
| 47 | checkNotNull(configurationKey, "configurationKey"); |
| 48 | try { |
| 49 | return injector.getInstance(Key.get(String.class, Names.named(configurationKey))); |
| 50 | } catch (ConfigurationException e) { |
| 51 | return null; |
| 52 | } |
| 53 | } |
| 54 | |
| 55 | } |