001/* 002 * Copyright 2002-2020 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.web.accept; 018 019import java.util.ArrayList; 020import java.util.Collections; 021import java.util.HashSet; 022import java.util.List; 023import java.util.Locale; 024import java.util.Map; 025import java.util.Set; 026import java.util.concurrent.ConcurrentHashMap; 027import java.util.concurrent.ConcurrentMap; 028import java.util.concurrent.CopyOnWriteArrayList; 029 030import org.springframework.http.MediaType; 031import org.springframework.lang.Nullable; 032 033/** 034 * An implementation of {@code MediaTypeFileExtensionResolver} that maintains 035 * lookups between file extensions and MediaTypes in both directions. 036 * 037 * <p>Initially created with a map of file extensions and media types. 038 * Subsequently subclasses can use {@link #addMapping} to add more mappings. 039 * 040 * @author Rossen Stoyanchev 041 * @author Juergen Hoeller 042 * @since 3.2 043 */ 044public class MappingMediaTypeFileExtensionResolver implements MediaTypeFileExtensionResolver { 045 046 private final ConcurrentMap<String, MediaType> mediaTypes = new ConcurrentHashMap<>(64); 047 048 private final ConcurrentMap<MediaType, List<String>> fileExtensions = new ConcurrentHashMap<>(64); 049 050 private final List<String> allFileExtensions = new CopyOnWriteArrayList<>(); 051 052 053 /** 054 * Create an instance with the given map of file extensions and media types. 055 */ 056 public MappingMediaTypeFileExtensionResolver(@Nullable Map<String, MediaType> mediaTypes) { 057 if (mediaTypes != null) { 058 Set<String> allFileExtensions = new HashSet<>(mediaTypes.size()); 059 mediaTypes.forEach((extension, mediaType) -> { 060 String lowerCaseExtension = extension.toLowerCase(Locale.ENGLISH); 061 this.mediaTypes.put(lowerCaseExtension, mediaType); 062 addFileExtension(mediaType, lowerCaseExtension); 063 allFileExtensions.add(lowerCaseExtension); 064 }); 065 this.allFileExtensions.addAll(allFileExtensions); 066 } 067 } 068 069 070 public Map<String, MediaType> getMediaTypes() { 071 return this.mediaTypes; 072 } 073 074 protected List<MediaType> getAllMediaTypes() { 075 return new ArrayList<>(this.mediaTypes.values()); 076 } 077 078 /** 079 * Map an extension to a MediaType. Ignore if extension already mapped. 080 */ 081 protected void addMapping(String extension, MediaType mediaType) { 082 MediaType previous = this.mediaTypes.putIfAbsent(extension, mediaType); 083 if (previous == null) { 084 addFileExtension(mediaType, extension); 085 this.allFileExtensions.add(extension); 086 } 087 } 088 089 private void addFileExtension(MediaType mediaType, String extension) { 090 this.fileExtensions.computeIfAbsent(mediaType, key -> new CopyOnWriteArrayList<>()) 091 .add(extension); 092 } 093 094 095 @Override 096 public List<String> resolveFileExtensions(MediaType mediaType) { 097 List<String> fileExtensions = this.fileExtensions.get(mediaType); 098 return (fileExtensions != null ? fileExtensions : Collections.emptyList()); 099 } 100 101 @Override 102 public List<String> getAllFileExtensions() { 103 return Collections.unmodifiableList(this.allFileExtensions); 104 } 105 106 /** 107 * Use this method for a reverse lookup from extension to MediaType. 108 * @return a MediaType for the extension, or {@code null} if none found 109 */ 110 @Nullable 111 protected MediaType lookupMediaType(String extension) { 112 return this.mediaTypes.get(extension.toLowerCase(Locale.ENGLISH)); 113 } 114 115}