/*
* Copyright 2002-2016 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
*
* 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.springframework.core.env;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import org.springframework.util.StringUtils;
/**
* Composite {@link PropertySource} implementation that iterates over a set of
* {@link PropertySource} instances. Necessary in cases where multiple property sources
* share the same name, e.g. when multiple values are supplied to {@code @PropertySource}.
*
* <p>As of Spring 4.1.2, this class extends {@link EnumerablePropertySource} instead
* of plain {@link PropertySource}, exposing {@link #getPropertyNames()} based on the
* accumulated property names from all contained sources (as far as possible).
*
* @author Chris Beams
* @author Juergen Hoeller
* @author Phillip Webb
* @since 3.1.1
*/
public class CompositePropertySource extends EnumerablePropertySource<Object> {
private final Set<PropertySource<?>> propertySources = new LinkedHashSet<>();
/**
* Create a new {@code CompositePropertySource}.
* @param name the name of the property source
*/
public CompositePropertySource(String name) {
super(name);
}
@Override
public Object getProperty(String name) {
for (PropertySource<?> propertySource : this.propertySources) {
Object candidate = propertySource.getProperty(name);
if (candidate != null) {
return candidate;
}
}
return null;
}
@Override
public boolean containsProperty(String name) {
for (PropertySource<?> propertySource : this.propertySources) {
if (propertySource.containsProperty(name)) {
return true;
}
}
return false;
}
@Override
public String[] getPropertyNames() {
Set<String> names = new LinkedHashSet<>();
for (PropertySource<?> propertySource : this.propertySources) {
if (!(propertySource instanceof EnumerablePropertySource)) {
throw new IllegalStateException(
"Failed to enumerate property names due to non-enumerable property source: " + propertySource);
}
names.addAll(Arrays.asList(((EnumerablePropertySource<?>) propertySource).getPropertyNames()));
}
return StringUtils.toStringArray(names);
}
/**
* Add the given {@link PropertySource} to the end of the chain.
* @param propertySource the PropertySource to add
*/
public void addPropertySource(PropertySource<?> propertySource) {
this.propertySources.add(propertySource);
}
/**
* Add the given {@link PropertySource} to the start of the chain.
* @param propertySource the PropertySource to add
* @since 4.1
*/
public void addFirstPropertySource(PropertySource<?> propertySource) {
List<PropertySource<?>> existing = new ArrayList<>(this.propertySources);
this.propertySources.clear();
this.propertySources.add(propertySource);
this.propertySources.addAll(existing);
}
/**
* Return all property sources that this composite source holds.
* @since 4.1.1
*/
public Collection<PropertySource<?>> getPropertySources() {
return this.propertySources;
}
@Override
public String toString() {
return String.format("%s [name='%s', propertySources=%s]",
getClass().getSimpleName(), this.name, this.propertySources);
}
}