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Tools to assist in the reading of configuration/preferences files in
various formats
/*
* 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;
/**
* A Configuration implementation that reads the platform specific
* environment variables using the map returned by {@link System#getenv()}.
*
* 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}
*
* 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.:
*
*
* Configuration envConfig = new EnvironmentConfiguration();
* System.out.println("JAVA_HOME=" + envConfig.getString("JAVA_HOME");
*
*
* @author Nicolas De Loof
* @version $Id: EnvironmentConfiguration.java 1842194 2018-09-27 22:24:23Z ggregory $
* @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!");
}
}