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.context.support; 018 019import java.util.Locale; 020 021import org.springframework.context.HierarchicalMessageSource; 022import org.springframework.context.MessageSource; 023import org.springframework.context.MessageSourceResolvable; 024import org.springframework.context.NoSuchMessageException; 025import org.springframework.lang.Nullable; 026 027/** 028 * Empty {@link MessageSource} that delegates all calls to the parent MessageSource. 029 * If no parent is available, it simply won't resolve any message. 030 * 031 * <p>Used as placeholder by AbstractApplicationContext, if the context doesn't 032 * define its own MessageSource. Not intended for direct use in applications. 033 * 034 * @author Juergen Hoeller 035 * @since 1.1.5 036 * @see AbstractApplicationContext 037 */ 038public class DelegatingMessageSource extends MessageSourceSupport implements HierarchicalMessageSource { 039 040 @Nullable 041 private MessageSource parentMessageSource; 042 043 044 @Override 045 public void setParentMessageSource(@Nullable MessageSource parent) { 046 this.parentMessageSource = parent; 047 } 048 049 @Override 050 @Nullable 051 public MessageSource getParentMessageSource() { 052 return this.parentMessageSource; 053 } 054 055 056 @Override 057 @Nullable 058 public String getMessage(String code, @Nullable Object[] args, @Nullable String defaultMessage, Locale locale) { 059 if (this.parentMessageSource != null) { 060 return this.parentMessageSource.getMessage(code, args, defaultMessage, locale); 061 } 062 else if (defaultMessage != null) { 063 return renderDefaultMessage(defaultMessage, args, locale); 064 } 065 else { 066 return null; 067 } 068 } 069 070 @Override 071 public String getMessage(String code, @Nullable Object[] args, Locale locale) throws NoSuchMessageException { 072 if (this.parentMessageSource != null) { 073 return this.parentMessageSource.getMessage(code, args, locale); 074 } 075 else { 076 throw new NoSuchMessageException(code, locale); 077 } 078 } 079 080 @Override 081 public String getMessage(MessageSourceResolvable resolvable, Locale locale) throws NoSuchMessageException { 082 if (this.parentMessageSource != null) { 083 return this.parentMessageSource.getMessage(resolvable, locale); 084 } 085 else { 086 if (resolvable.getDefaultMessage() != null) { 087 return renderDefaultMessage(resolvable.getDefaultMessage(), resolvable.getArguments(), locale); 088 } 089 String[] codes = resolvable.getCodes(); 090 String code = (codes != null && codes.length > 0 ? codes[0] : ""); 091 throw new NoSuchMessageException(code, locale); 092 } 093 } 094 095 096 @Override 097 public String toString() { 098 return this.parentMessageSource != null ? this.parentMessageSource.toString() : "Empty MessageSource"; 099 } 100 101}