| /* |
| * 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.commons.configuration2; |
| |
| import java.util.HashMap; |
| |
| /** |
| * <p>A Configuration implementation that reads the platform specific |
| * environment variables using the map returned by {@link System#getenv()}.</p> |
| * |
| * <p>This configuration implementation is read-only. It allows read access to the |
| * defined OS environment variables, but their values cannot be changed. Any |
| * attempts to add or remove a property will throw an |
| * {@link UnsupportedOperationException}</p> |
| * |
| * <p>Usage of this class is easy: After an instance has been created the get |
| * methods provided by the {@code Configuration} interface can be used |
| * for querying environment variables, e.g.:</p> |
| * |
| * <pre> |
| * Configuration envConfig = new EnvironmentConfiguration(); |
| * System.out.println("JAVA_HOME=" + envConfig.getString("JAVA_HOME"); |
| * </pre> |
| * |
| * @since 1.5 |
| */ |
| public class EnvironmentConfiguration extends MapConfiguration |
| { |
| /** |
| * Create a Configuration based on the environment variables. |
| * |
| * @see System#getenv() |
| */ |
| public EnvironmentConfiguration() |
| { |
| super(new HashMap<>(System.getenv())); |
| } |
| |
| /** |
| * Adds a property to this configuration. Because this configuration is |
| * read-only, this operation is not allowed and will cause an exception. |
| * |
| * @param key the key of the property to be added |
| * @param value the property value |
| */ |
| @Override |
| protected void addPropertyDirect(final String key, final Object value) |
| { |
| throw new UnsupportedOperationException("EnvironmentConfiguration is read-only!"); |
| } |
| |
| /** |
| * Removes a property from this configuration. Because this configuration is |
| * read-only, this operation is not allowed and will cause an exception. |
| * |
| * @param key the key of the property to be removed |
| */ |
| @Override |
| protected void clearPropertyDirect(final String key) |
| { |
| throw new UnsupportedOperationException("EnvironmentConfiguration is read-only!"); |
| } |
| |
| /** |
| * Removes all properties from this configuration. Because this |
| * configuration is read-only, this operation is not allowed and will cause |
| * an exception. |
| */ |
| @Override |
| protected void clearInternal() |
| { |
| throw new UnsupportedOperationException("EnvironmentConfiguration is read-only!"); |
| } |
| } |