/**
* Copyright (C) cedarsoft GmbH.
*
* Licensed under the GNU General Public License version 3 (the "License")
* with Classpath Exception; you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.cedarsoft.org/gpl3ce
* (GPL 3 with Classpath Exception)
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 3 only, as
* published by the Free Software Foundation. cedarsoft GmbH designates this
* particular file as subject to the "Classpath" exception as provided
* by cedarsoft GmbH in the LICENSE file that accompanied this code.
*
* This code 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 General Public License
* version 3 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 3 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact cedarsoft GmbH, 72810 Gomaringen, Germany,
* or visit www.cedarsoft.com if you need additional information or
* have any questions.
*/
package com.cedarsoft.configuration.xml;
import com.cedarsoft.configuration.DefaultValueProvider;
import org.apache.commons.configuration.Configuration;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.lang.Class;
import java.lang.IllegalArgumentException;
import java.lang.String;
import java.util.NoSuchElementException;
/**
* Offers common access to configurations.
* Implementations are independant of the type.
*
* @author Johannes Schneider (<a href=mailto:js@cedarsoft.com>js@cedarsoft.com</a>)
*/
public class ConfigurationAccess<T> {
@Nonnull
private final Class<? extends T> type;
@Nonnull
private final String key;
@Nonnull
private final ConfigurationResolver<T> resolver;
@Nonnull
private final DefaultValueProvider defaultValueProvider;
@Nonnull
private final Configuration configuration;
/**
* <p>Constructor for ConfigurationAccess.</p>
*
* @param configuration a Configuration object.
* @param type a Class object.
* @param key a String object.
* @param defaultValue a T object.
*/
public ConfigurationAccess( @Nonnull Configuration configuration, @Nonnull Class<? extends T> type, @Nonnull String key, @Nonnull final T defaultValue ) {
this( configuration, type, key, new DefaultValueProvider() {
@Override
@Nonnull
public <T> T getDefaultValue( @Nonnull String key, @Nonnull Class<T> type ) {
return type.cast( defaultValue );
}
} );
}
/**
* <p>Constructor for ConfigurationAccess.</p>
*
* @param configuration a Configuration object.
* @param type a Class object.
* @param key a String object.
* @param defaultValueProvider a DefaultValueProvider object.
*/
public ConfigurationAccess( @Nonnull Configuration configuration, @Nonnull Class<? extends T> type, @Nonnull String key, @Nonnull DefaultValueProvider defaultValueProvider ) {
this( configuration, type, key, defaultValueProvider, ConfigurationResolver.getResolver( type ) );
}
/**
* <p>Constructor for ConfigurationAccess.</p>
*
* @param configuration a Configuration object.
* @param type a Class object.
* @param key a String object.
* @param defaultValueProvider a DefaultValueProvider object.
* @param resolver a ConfigurationResolver object.
*/
public ConfigurationAccess( @Nonnull Configuration configuration, @Nonnull Class<? extends T> type, @Nonnull String key, @Nonnull DefaultValueProvider defaultValueProvider, @Nonnull ConfigurationResolver<T> resolver ) {
this.configuration = configuration;
this.type = type;
this.key = key;
this.defaultValueProvider = defaultValueProvider;
this.resolver = resolver;
}
/**
* <p>resolve</p>
*
* @return a T object.
*/
@Nullable
public T resolve() {
try {
T resolved = resolver.resolve( configuration, key );
if ( resolved != null ) {
return resolved;
}
} catch ( NoSuchElementException ignore ) {
}
T defaultValue = defaultValueProvider.getDefaultValue( key, type );
if ( defaultValue != null ) {
resolver.store( configuration, key, defaultValue );
}
return defaultValue;
}
/**
* Resolves the value
*
* @return the resolved value
*
* @throws IllegalArgumentException
* if the key is invalid
*/
@Nonnull
public T resolveSafe() throws IllegalArgumentException {
T resolved = resolve();
if ( resolved == null ) {
throw new IllegalArgumentException( "No configured value found for " + key );
}
return resolved;
}
/**
* <p>Getter for the field <code>type</code>.</p>
*
* @return a Class object.
*/
@Nonnull
public Class<? extends T> getType() {
return type;
}
/**
* <p>Getter for the field <code>key</code>.</p>
*
* @return a String object.
*/
@Nonnull
public String getKey() {
return key;
}
/**
* <p>store</p>
*
* @param value a T object.
*/
public void store( @Nonnull T value ) {
resolver.store( configuration, key, value );
}
}