001/* 002 * Copyright 2002-2017 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.core.env; 018 019import java.util.ArrayList; 020import java.util.Arrays; 021import java.util.Collection; 022import java.util.LinkedHashSet; 023import java.util.List; 024import java.util.Set; 025 026import org.springframework.lang.Nullable; 027import org.springframework.util.StringUtils; 028 029/** 030 * Composite {@link PropertySource} implementation that iterates over a set of 031 * {@link PropertySource} instances. Necessary in cases where multiple property sources 032 * share the same name, e.g. when multiple values are supplied to {@code @PropertySource}. 033 * 034 * <p>As of Spring 4.1.2, this class extends {@link EnumerablePropertySource} instead 035 * of plain {@link PropertySource}, exposing {@link #getPropertyNames()} based on the 036 * accumulated property names from all contained sources (as far as possible). 037 * 038 * @author Chris Beams 039 * @author Juergen Hoeller 040 * @author Phillip Webb 041 * @since 3.1.1 042 */ 043public class CompositePropertySource extends EnumerablePropertySource<Object> { 044 045 private final Set<PropertySource<?>> propertySources = new LinkedHashSet<>(); 046 047 048 /** 049 * Create a new {@code CompositePropertySource}. 050 * @param name the name of the property source 051 */ 052 public CompositePropertySource(String name) { 053 super(name); 054 } 055 056 057 @Override 058 @Nullable 059 public Object getProperty(String name) { 060 for (PropertySource<?> propertySource : this.propertySources) { 061 Object candidate = propertySource.getProperty(name); 062 if (candidate != null) { 063 return candidate; 064 } 065 } 066 return null; 067 } 068 069 @Override 070 public boolean containsProperty(String name) { 071 for (PropertySource<?> propertySource : this.propertySources) { 072 if (propertySource.containsProperty(name)) { 073 return true; 074 } 075 } 076 return false; 077 } 078 079 @Override 080 public String[] getPropertyNames() { 081 Set<String> names = new LinkedHashSet<>(); 082 for (PropertySource<?> propertySource : this.propertySources) { 083 if (!(propertySource instanceof EnumerablePropertySource)) { 084 throw new IllegalStateException( 085 "Failed to enumerate property names due to non-enumerable property source: " + propertySource); 086 } 087 names.addAll(Arrays.asList(((EnumerablePropertySource<?>) propertySource).getPropertyNames())); 088 } 089 return StringUtils.toStringArray(names); 090 } 091 092 093 /** 094 * Add the given {@link PropertySource} to the end of the chain. 095 * @param propertySource the PropertySource to add 096 */ 097 public void addPropertySource(PropertySource<?> propertySource) { 098 this.propertySources.add(propertySource); 099 } 100 101 /** 102 * Add the given {@link PropertySource} to the start of the chain. 103 * @param propertySource the PropertySource to add 104 * @since 4.1 105 */ 106 public void addFirstPropertySource(PropertySource<?> propertySource) { 107 List<PropertySource<?>> existing = new ArrayList<>(this.propertySources); 108 this.propertySources.clear(); 109 this.propertySources.add(propertySource); 110 this.propertySources.addAll(existing); 111 } 112 113 /** 114 * Return all property sources that this composite source holds. 115 * @since 4.1.1 116 */ 117 public Collection<PropertySource<?>> getPropertySources() { 118 return this.propertySources; 119 } 120 121 122 @Override 123 public String toString() { 124 return getClass().getSimpleName() + " {name='" + this.name + "', propertySources=" + this.propertySources + "}"; 125 } 126 127}