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jtstand-common is a library derived from jcommon, used by jtstand-chart, which is derived from jfreechart
There is a newer version: 1.5.9
/*
 * Copyright (c) 2009 Albert Kurucz. 
 *
 * This file, SystemPropertyConfiguration.java is part of JTStand.
 *
 * JTStand is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * JTStand is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with GTStand.  If not, see .
 */

package org.jfree.base.config;

import java.util.Enumeration;
import java.util.Vector;

/**
 * A property configuration based on system properties.
 *
 * @author Thomas Morgner
 */
public class SystemPropertyConfiguration extends HierarchicalConfiguration {

    /**
     * Creates a report configuration that includes all the system properties (whether they are
     * related to reports or not).  The parent configuration is a
     * PropertyFileConfiguration.
     */
    public SystemPropertyConfiguration() {
    }

    /**
     * Sets a configuration property.
     *
     * @param key  the property key.
     * @param value  the property value.
     */
    public void setConfigProperty(final String key, final String value) {
        throw new UnsupportedOperationException("The SystemPropertyConfiguration is readOnly");
    }

    /**
     * Returns the configuration property with the specified key (or the specified default value
     * if there is no such property).
     * 
     * If the property is not defined in this configuration, the code will lookup the property in
     * the parent configuration.
     *
     * @param key  the property key.
     * @param defaultValue  the default value.
     *
     * @return the property value.
     */
    public String getConfigProperty(final String key, final String defaultValue) {
        try {
            final String value = System.getProperty(key);
            if (value != null) {
               return value;
            }
        }
        catch (SecurityException se) {
            // ignore security exceptions, continue as if the property was not set..
        }
        return super.getConfigProperty(key, defaultValue);
    }

    /**
     * Checks, whether the given key is locally defined in the system properties.
     * @see HierarchicalConfiguration#isLocallyDefined(java.lang.String)
     *
     * @param key the key that should be checked.
     * @return true, if the key is defined in the system properties, false otherwise.
     */
    public boolean isLocallyDefined(final String key) {
        try {
            return System.getProperties().containsKey(key);
        }
        catch (SecurityException se) {
            return false;
        }
    }

    /**
     * Returns all defined configuration properties for the report. The enumeration
     * contains all keys of the changed properties, properties set from files or
     * the system properties are not included.
     *
     * @return all defined configuration properties for the report.
     */
    public Enumeration getConfigProperties() {
        try {
            return System.getProperties().keys();
        }
        catch (SecurityException se) {
            // should return an empty enumeration ...
            return new Vector().elements();
        }
    }
}