| /* |
| * Copyright (C) 2019 The Android Open Source Project |
| * |
| * 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 android.content.type; |
| |
| import libcore.net.MimeMap; |
| |
| import java.io.BufferedReader; |
| import java.io.IOException; |
| import java.io.InputStreamReader; |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.regex.Pattern; |
| |
| /** |
| * Default implementation of {@link MimeMap}, a bidirectional mapping between |
| * MIME types and file extensions. |
| * |
| * This default mapping is loaded from data files that start with some mappings |
| * recognized by IANA plus some custom extensions and overrides. |
| * |
| * @hide |
| */ |
| public class MimeMapImpl extends MimeMap { |
| |
| /** |
| * Creates and returns a new {@link MimeMapImpl} instance that implements. |
| * Android's default mapping between MIME types and extensions. |
| */ |
| public static MimeMapImpl createDefaultInstance() { |
| return parseFromResources("/mime.types", "/android.mime.types"); |
| } |
| |
| private static final Pattern SPLIT_PATTERN = Pattern.compile("\\s+"); |
| |
| /** |
| * Note: These maps only contain lowercase keys/values, regarded as the |
| * {@link #toLowerCase(String) canonical form}. |
| * |
| * <p>This is the case for both extensions and MIME types. The mime.types |
| * data file contains examples of mixed-case MIME types, but some applications |
| * use the lowercase version of these same types. RFC 2045 section 2 states |
| * that MIME types are case insensitive. |
| */ |
| private final Map<String, String> mMimeTypeToExtension; |
| private final Map<String, String> mExtensionToMimeType; |
| |
| public MimeMapImpl(Map<String, String> mimeTypeToExtension, |
| Map<String, String> extensionToMimeType) { |
| this.mMimeTypeToExtension = new HashMap<>(mimeTypeToExtension); |
| for (Map.Entry<String, String> entry : mimeTypeToExtension.entrySet()) { |
| checkValidMimeType(entry.getKey()); |
| checkValidExtension(entry.getValue()); |
| } |
| this.mExtensionToMimeType = new HashMap<>(extensionToMimeType); |
| for (Map.Entry<String, String> entry : extensionToMimeType.entrySet()) { |
| checkValidExtension(entry.getKey()); |
| checkValidMimeType(entry.getValue()); |
| } |
| } |
| |
| private static void checkValidMimeType(String s) { |
| if (MimeMap.isNullOrEmpty(s) || !s.equals(MimeMap.toLowerCase(s))) { |
| throw new IllegalArgumentException("Invalid MIME type: " + s); |
| } |
| } |
| |
| private static void checkValidExtension(String s) { |
| if (MimeMap.isNullOrEmpty(s) || !s.equals(MimeMap.toLowerCase(s))) { |
| throw new IllegalArgumentException("Invalid extension: " + s); |
| } |
| } |
| |
| static MimeMapImpl parseFromResources(String... resourceNames) { |
| Map<String, String> mimeTypeToExtension = new HashMap<>(); |
| Map<String, String> extensionToMimeType = new HashMap<>(); |
| for (String resourceName : resourceNames) { |
| parseTypes(mimeTypeToExtension, extensionToMimeType, resourceName); |
| } |
| return new MimeMapImpl(mimeTypeToExtension, extensionToMimeType); |
| } |
| |
| /** |
| * An element of a *mime.types file: A MIME type or an extension, with an optional |
| * prefix of "?" (if not overriding an earlier value). |
| */ |
| private static class Element { |
| public final boolean keepExisting; |
| public final String s; |
| |
| Element(boolean keepExisting, String value) { |
| this.keepExisting = keepExisting; |
| this.s = toLowerCase(value); |
| if (value.isEmpty()) { |
| throw new IllegalArgumentException(); |
| } |
| } |
| |
| public String toString() { |
| return keepExisting ? ("?" + s) : s; |
| } |
| } |
| |
| private static String maybePut(Map<String, String> map, Element keyElement, String value) { |
| if (keyElement.keepExisting) { |
| return map.putIfAbsent(keyElement.s, value); |
| } else { |
| return map.put(keyElement.s, value); |
| } |
| } |
| |
| private static void parseTypes(Map<String, String> mimeTypeToExtension, |
| Map<String, String> extensionToMimeType, String resource) { |
| try (BufferedReader r = new BufferedReader( |
| new InputStreamReader(MimeMapImpl.class.getResourceAsStream(resource)))) { |
| String line; |
| while ((line = r.readLine()) != null) { |
| int commentPos = line.indexOf('#'); |
| if (commentPos >= 0) { |
| line = line.substring(0, commentPos); |
| } |
| line = line.trim(); |
| // The first time a MIME type is encountered it is mapped to the first extension |
| // listed in its line. The first time an extension is encountered it is mapped |
| // to the MIME type. |
| // |
| // When encountering a previously seen MIME type or extension, then by default |
| // the later ones override earlier mappings (put() semantics); however if a MIME |
| // type or extension is prefixed with '?' then any earlier mapping _from_ that |
| // MIME type / extension is kept (putIfAbsent() semantics). |
| final String[] split = SPLIT_PATTERN.split(line); |
| if (split.length <= 1) { |
| // Need mimeType + at least one extension to make a mapping. |
| // "mime.types" files may also contain lines with just a mimeType without |
| // an extension but we skip them as they provide no mapping info. |
| continue; |
| } |
| List<Element> lineElements = new ArrayList<>(split.length); |
| for (String s : split) { |
| boolean keepExisting = s.startsWith("?"); |
| if (keepExisting) { |
| s = s.substring(1); |
| } |
| if (s.isEmpty()) { |
| throw new IllegalArgumentException("Invalid entry in '" + line + "'"); |
| } |
| lineElements.add(new Element(keepExisting, s)); |
| } |
| |
| // MIME type -> first extension (one mapping) |
| // This will override any earlier mapping from this MIME type to another |
| // extension, unless this MIME type was prefixed with '?'. |
| Element mimeElement = lineElements.get(0); |
| List<Element> extensionElements = lineElements.subList(1, lineElements.size()); |
| String firstExtension = extensionElements.get(0).s; |
| maybePut(mimeTypeToExtension, mimeElement, firstExtension); |
| |
| // extension -> MIME type (one or more mappings). |
| // This will override any earlier mapping from this extension to another |
| // MIME type, unless this extension was prefixed with '?'. |
| for (Element extensionElement : extensionElements) { |
| maybePut(extensionToMimeType, extensionElement, mimeElement.s); |
| } |
| } |
| } catch (IOException | RuntimeException e) { |
| throw new RuntimeException("Failed to parse " + resource, e); |
| } |
| } |
| |
| @Override |
| protected String guessExtensionFromLowerCaseMimeType(String mimeType) { |
| return mMimeTypeToExtension.get(mimeType); |
| } |
| |
| @Override |
| protected String guessMimeTypeFromLowerCaseExtension(String extension) { |
| return mExtensionToMimeType.get(extension); |
| } |
| } |