Java tutorial
/* * Copyright 2002-2017 the original author or authors. * * Licensed 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 * * https://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.springframework.beans.factory.support; import java.util.Properties; import org.springframework.beans.BeanMetadataElement; import org.springframework.beans.Mergeable; import org.springframework.lang.Nullable; /** * Tag class which represents a Spring-managed {@link Properties} instance * that supports merging of parent/child definitions. * * @author Rob Harrop * @author Juergen Hoeller * @since 2.0 */ @SuppressWarnings("serial") public class ManagedProperties extends Properties implements Mergeable, BeanMetadataElement { @Nullable private Object source; private boolean mergeEnabled; /** * Set the configuration source {@code Object} for this metadata element. * <p>The exact type of the object will depend on the configuration mechanism used. */ public void setSource(@Nullable Object source) { this.source = source; } @Override @Nullable public Object getSource() { return this.source; } /** * Set whether merging should be enabled for this collection, * in case of a 'parent' collection value being present. */ public void setMergeEnabled(boolean mergeEnabled) { this.mergeEnabled = mergeEnabled; } @Override public boolean isMergeEnabled() { return this.mergeEnabled; } @Override public Object merge(@Nullable Object parent) { if (!this.mergeEnabled) { throw new IllegalStateException( "Not allowed to merge when the 'mergeEnabled' property is set to 'false'"); } if (parent == null) { return this; } if (!(parent instanceof Properties)) { throw new IllegalArgumentException("Cannot merge with object of type [" + parent.getClass() + "]"); } Properties merged = new ManagedProperties(); merged.putAll((Properties) parent); merged.putAll(this); return merged; } }