Java tutorial
/* * Copyright (C) 2015 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.android.messaging.datamodel; import android.content.ContentResolver; import android.content.Context; import android.database.Cursor; import android.database.MatrixCursor; import android.database.MatrixCursor.RowBuilder; import android.net.Uri; import android.provider.OpenableColumns; import android.support.v4.util.SimpleArrayMap; import android.text.TextUtils; import com.android.messaging.Factory; import com.android.messaging.util.Assert; import com.android.messaging.util.LogUtil; import com.google.common.annotations.VisibleForTesting; import java.io.File; import java.util.List; /** * A very simple content provider that can serve media files from our cache directory. */ public class MediaScratchFileProvider extends FileProvider { private static final String TAG = LogUtil.BUGLE_TAG; private static final SimpleArrayMap<Uri, String> sUriToDisplayNameMap = new SimpleArrayMap<Uri, String>(); @VisibleForTesting public static final String AUTHORITY = "com.android.messaging.datamodel.MediaScratchFileProvider"; private static final String MEDIA_SCRATCH_SPACE_DIR = "mediascratchspace"; public static boolean isMediaScratchSpaceUri(final Uri uri) { if (uri == null) { return false; } final List<String> segments = uri.getPathSegments(); return (TextUtils.equals(uri.getScheme(), ContentResolver.SCHEME_CONTENT) && TextUtils.equals(uri.getAuthority(), AUTHORITY) && segments.size() == 1 && FileProvider.isValidFileId(segments.get(0))); } /** * Returns a uri that can be used to access a raw mms file. * * @return the URI for an raw mms file */ public static Uri buildMediaScratchSpaceUri(final String extension) { final Uri uri = FileProvider.buildFileUri(AUTHORITY, extension); final File file = getFileWithExtension(uri.getPath(), extension); if (!ensureFileExists(file)) { LogUtil.e(TAG, "Failed to create temp file " + file.getAbsolutePath()); } return uri; } public static File getFileFromUri(final Uri uri) { Assert.equals(AUTHORITY, uri.getAuthority()); return getFileWithExtension(uri.getPath(), getExtensionFromUri(uri)); } public static Uri.Builder getUriBuilder() { return (new Uri.Builder()).authority(AUTHORITY).scheme(ContentResolver.SCHEME_CONTENT); } @Override File getFile(final String path, final String extension) { return getFileWithExtension(path, extension); } private static File getFileWithExtension(final String path, final String extension) { final Context context = Factory.get().getApplicationContext(); return new File(getDirectory(context), TextUtils.isEmpty(extension) ? path : path + "." + extension); } private static File getDirectory(final Context context) { return new File(context.getCacheDir(), MEDIA_SCRATCH_SPACE_DIR); } @Override public Cursor query(final Uri uri, final String[] projection, final String selection, final String[] selectionArgs, final String sortOrder) { if (projection != null && projection.length > 0 && TextUtils.equals(projection[0], OpenableColumns.DISPLAY_NAME) && isMediaScratchSpaceUri(uri)) { // Retrieve the display name associated with a temp file. This is used by the Contacts // ImportVCardActivity to retrieve the name of the contact(s) being imported. String displayName; synchronized (sUriToDisplayNameMap) { displayName = sUriToDisplayNameMap.get(uri); } if (!TextUtils.isEmpty(displayName)) { MatrixCursor cursor = new MatrixCursor(new String[] { OpenableColumns.DISPLAY_NAME }); RowBuilder row = cursor.newRow(); row.add(displayName); return cursor; } } return null; } public static void addUriToDisplayNameEntry(final Uri scratchFileUri, final String displayName) { if (TextUtils.isEmpty(displayName)) { return; } synchronized (sUriToDisplayNameMap) { sUriToDisplayNameMap.put(scratchFileUri, displayName); } } }