| /* |
| * Copyright (C) 2013 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 com.example.android.common.assetprovider; |
| |
| import android.content.ContentProvider; |
| import android.content.ContentValues; |
| import android.content.Context; |
| import android.content.res.AssetFileDescriptor; |
| import android.content.res.AssetManager; |
| import android.database.Cursor; |
| import android.net.Uri; |
| |
| import java.io.FileNotFoundException; |
| import java.io.IOException; |
| |
| import static java.net.URLConnection.guessContentTypeFromName; |
| |
| /** |
| * Generic content provider, which makes any files available in this app's "assets" directory |
| * available publicly. |
| * |
| * <p>To use, add the following to your AndroidManifest.xml: |
| * |
| * <code><pre> |
| * <provider |
| * android:name=".AssetProvider" |
| * android:authorities="[YOUR CONTENT PROVIDER DOMAIN HERE]" |
| * android:exported="true"/> |
| * </pre></code> |
| */ |
| public class AssetProvider extends ContentProvider { |
| AssetManager mAssets; |
| |
| @Override |
| public boolean onCreate() { |
| Context ctx = getContext(); |
| if (ctx == null) { |
| // Context not available. Give up. |
| return false; |
| } |
| mAssets = ctx.getAssets(); |
| return true; |
| } |
| |
| @Override |
| public String getType(Uri uri){ |
| // Returns the MIME type for the selected URI, in conformance with the ContentProvider |
| // interface. Looks up the file indicated by /res/assets/{uri.path}, and returns the MIME |
| // type for that file as guessed by the URLConnection class. |
| |
| // Setup |
| String path = uri.getPath(); |
| |
| // Check if file exists |
| if (!fileExists(path)) { |
| return null; |
| } |
| |
| // Determine MIME-type based on filename |
| return guessContentTypeFromName(uri.toString()); |
| } |
| |
| |
| @Override |
| public AssetFileDescriptor openAssetFile (Uri uri, String mode) |
| throws FileNotFoundException, SecurityException { |
| // ContentProvider interface for opening a file descriptor by URI. This content provider |
| // maps all URIs to the contents of the APK's assets folder, so a file handle to |
| // /res/assets/{uri.path} will be returned. |
| |
| // Security check. This content provider only supports read-only access. (Also, the contents |
| // of an APKs assets folder are immutable, so read-write access doesn't make sense here.) |
| if (!"r".equals(mode)) { |
| throw new SecurityException("Only read-only access is supported, mode must be [r]"); |
| } |
| |
| // Open asset from within APK and return file descriptor |
| String path = uri.getPath(); |
| try { |
| return mAssets.openFd(path); |
| } catch (IOException e) { |
| throw new FileNotFoundException(); |
| } |
| } |
| |
| /** |
| * Check if file exists inside APK assets. |
| * |
| * @param path Fully qualified path to file. |
| * @return true if exists, false otherwise. |
| */ |
| private boolean fileExists(String path) { |
| try { |
| // Check to see if file can be opened. If so, file exists. |
| mAssets.openFd(path).close(); |
| return true; |
| } catch (IOException e) { |
| // Unable to open file descriptor for specified path; file doesn't exist. |
| return false; |
| } |
| } |
| |
| // Required/unused ContentProvider methods below. |
| @Override |
| public Cursor query(Uri uri, String[] projection, String selection, |
| String[] selectionArgs, String sortOrder) { |
| // Note: It might be worth implementing support for querying |
| // android.provider.OpenableColumns here in the future. |
| throw new RuntimeException("Operation not supported"); |
| } |
| |
| @Override |
| public Uri insert(Uri uri, ContentValues contentValues) { |
| throw new RuntimeException("Operation not supported"); |
| } |
| |
| @Override |
| public int delete(Uri uri, String selection, String[] selectionArgs) { |
| throw new RuntimeException("Operation not supported"); |
| } |
| |
| @Override |
| public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { |
| throw new RuntimeException("Operation not supported"); |
| } |
| } |