Java tutorial
package com.iceteck.silicompressorr; /* Copyright (C) 2007-2008 OpenIntents.org * * 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. */ import android.content.ContentResolver; import android.content.ContentUris; import android.content.Context; import android.content.Intent; import android.database.Cursor; import android.database.DatabaseUtils; import android.graphics.Bitmap; import android.net.Uri; import android.os.Build; import android.os.Environment; import android.provider.DocumentsContract; import android.provider.MediaStore; import android.support.v4.content.FileProvider; import android.util.Log; import android.webkit.MimeTypeMap; import java.io.File; import java.io.FileFilter; import java.text.DecimalFormat; import java.util.Comparator; /** * @version 2009-07-03 * @author Peli * @version 2013-12-11 * @author paulburke (ipaulpro) */ public class FileUtils { private FileUtils() { } //private constructor to enforce Singleton pattern /** TAG for log messages. */ static final String TAG = "FileUtils"; private static final boolean DEBUG = false; // Set to true to enable logging public static final String MIME_TYPE_AUDIO = "audio/*"; public static final String MIME_TYPE_TEXT = "text/*"; public static final String MIME_TYPE_IMAGE = "image/*"; public static final String MIME_TYPE_VIDEO = "video/*"; public static final String MIME_TYPE_APP = "application/*"; public static final String HIDDEN_PREFIX = "."; /** * Gets the extension of a file name, like ".png" or ".jpg". * * @param uri * @return Extension including the dot("."); "" if there is no extension; * null if uri was null. */ public static String getExtension(String uri) { if (uri == null) { return null; } int dot = uri.lastIndexOf("."); if (dot >= 0) { return uri.substring(dot); } else { // No extension. return ""; } } /** * @return Whether the URI is a local one. */ public static boolean isLocal(String url) { if (url != null && !url.startsWith("http://") && !url.startsWith("https://")) { return true; } return false; } /** * @return True if Uri is a MediaStore Uri. * @author paulburke */ public static boolean isMediaUri(Uri uri) { return "media".equalsIgnoreCase(uri.getAuthority()); } /** * Convert File into Uri. * * @param file * @return uri */ public static Uri getUri(Context context, File file) { if (file != null) { return FileProvider.getUriForFile(context, SiliCompressor.getAuthorities(context), file); //Uri.fromFile(file); } return null; } /** * Returns the path only (without file name). * * @param file * @return */ public static File getPathWithoutFilename(File file) { if (file != null) { if (file.isDirectory()) { // no file to be split off. Return everything return file; } else { String filename = file.getName(); String filepath = file.getAbsolutePath(); // Construct path without file name. String pathwithoutname = filepath.substring(0, filepath.length() - filename.length()); if (pathwithoutname.endsWith("/")) { pathwithoutname = pathwithoutname.substring(0, pathwithoutname.length() - 1); } return new File(pathwithoutname); } } return null; } /** * @return The MIME type for the given file. */ public static String getMimeType(File file) { String extension = getExtension(file.getName()); if (extension.length() > 0) return MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension.substring(1)); return "application/octet-stream"; } /** * @return The MIME type for the give Uri. */ public static String getMimeType(Context context, Uri uri) { File file = new File(getPath(context, uri)); return getMimeType(file); } /** * @param uri The Uri to check. * @return Whether the Uri authority is ExternalStorageProvider. * @author paulburke */ public static boolean isExternalStorageDocument(Uri uri) { return "com.android.externalstorage.documents".equals(uri.getAuthority()); } /** * @param uri The Uri to check. * @return Whether the Uri authority is DownloadsProvider. * @author paulburke */ public static boolean isDownloadsDocument(Uri uri) { return "com.android.providers.downloads.documents".equals(uri.getAuthority()); } /** * @param uri The Uri to check. * @return Whether the Uri authority is MediaProvider. * @author paulburke */ public static boolean isMediaDocument(Uri uri) { return "com.android.providers.media.documents".equals(uri.getAuthority()); } /** * @param uri The Uri to check. * @return Whether the Uri authority is Google Photos. */ public static boolean isGooglePhotosUri(Uri uri) { return "com.google.android.apps.photos.content".equals(uri.getAuthority()); } /** * Get the value of the data column for this Uri. This is useful for * MediaStore Uris, and other file-based ContentProviders. * * @param context The context. * @param uri The Uri to query. * @param selection (Optional) Filter used in the query. * @param selectionArgs (Optional) Selection arguments used in the query. * @return The value of the _data column, which is typically a file path. * @author paulburke */ public static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) { Cursor cursor = null; final String column = "_data"; final String[] projection = { column }; try { cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null); if (cursor != null && cursor.moveToFirst()) { if (DEBUG) DatabaseUtils.dumpCursor(cursor); final int column_index = cursor.getColumnIndexOrThrow(column); return cursor.getString(column_index); } } finally { if (cursor != null) cursor.close(); } return null; } /** * Get a file path from a Uri. This will get the the path for Storage Access * Framework Documents, as well as the _data field for the MediaStore and * other file-based ContentProviders.<br> * <br> * Callers should check whether the path is local before assuming it * represents a local file. * * @param context The context. * @param uri The Uri to query. * @see #isLocal(String) * @see #getFile(Context, Uri) * @author paulburke */ public static String getPath(final Context context, final Uri uri) { if (DEBUG) Log.d(TAG + " File -", "Authority: " + uri.getAuthority() + ", Fragment: " + uri.getFragment() + ", Port: " + uri.getPort() + ", Query: " + uri.getQuery() + ", Scheme: " + uri.getScheme() + ", Host: " + uri.getHost() + ", Segments: " + uri.getPathSegments().toString()); final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT; // DocumentProvider if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT && DocumentsContract.isDocumentUri(context, uri)) { // ExternalStorageProvider if (isExternalStorageDocument(uri)) { final String docId = DocumentsContract.getDocumentId(uri); final String[] split = docId.split(":"); final String type = split[0]; if ("primary".equalsIgnoreCase(type)) { return Environment.getExternalStorageDirectory() + "/" + split[1]; } // TODO handle non-primary volumes } // DownloadsProvider else if (isDownloadsDocument(uri)) { final String id = DocumentsContract.getDocumentId(uri); final Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(id)); return getDataColumn(context, contentUri, null, null); } // MediaProvider else if (isMediaDocument(uri)) { final String docId = DocumentsContract.getDocumentId(uri); final String[] split = docId.split(":"); final String type = split[0]; Uri contentUri = null; if ("image".equals(type)) { contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI; } else if ("video".equals(type)) { contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI; } else if ("audio".equals(type)) { contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; } final String selection = "_id=?"; final String[] selectionArgs = new String[] { split[1] }; return getDataColumn(context, contentUri, selection, selectionArgs); } } // MediaStore (and general) else if ("content".equalsIgnoreCase(uri.getScheme())) { // Return the remote address if (isGooglePhotosUri(uri)) return uri.getLastPathSegment(); return getDataColumn(context, uri, null, null); } // File else if ("file".equalsIgnoreCase(uri.getScheme())) { return uri.getPath(); } return null; } /** * Convert Uri into File, if possible. * * @return file A local file that the Uri was pointing to, or null if the * Uri is unsupported or pointed to a remote resource. * @see #getPath(Context, Uri) * @author paulburke */ public static File getFile(Context context, Uri uri) { if (uri != null) { String path = getPath(context, uri); if (path != null && isLocal(path)) { return new File(path); } } return null; } /** * Get the file size in a human-readable string. * * @param size * @return * @author paulburke */ public static String getReadableFileSize(int size) { final int BYTES_IN_KILOBYTES = 1024; final DecimalFormat dec = new DecimalFormat("###.#"); final String KILOBYTES = " KB"; final String MEGABYTES = " MB"; final String GIGABYTES = " GB"; float fileSize = 0; String suffix = KILOBYTES; if (size > BYTES_IN_KILOBYTES) { fileSize = size / BYTES_IN_KILOBYTES; if (fileSize > BYTES_IN_KILOBYTES) { fileSize = fileSize / BYTES_IN_KILOBYTES; if (fileSize > BYTES_IN_KILOBYTES) { fileSize = fileSize / BYTES_IN_KILOBYTES; suffix = GIGABYTES; } else { suffix = MEGABYTES; } } } return String.valueOf(dec.format(fileSize) + suffix); } /** * Attempt to retrieve the thumbnail of given File from the MediaStore. This * should not be called on the UI thread. * * @param context * @param file * @return * @author paulburke */ public static Bitmap getThumbnail(Context context, File file) { return getThumbnail(context, getUri(context, file), getMimeType(file)); } /** * Attempt to retrieve the thumbnail of given Uri from the MediaStore. This * should not be called on the UI thread. * * @param context * @param uri * @return * @author paulburke */ public static Bitmap getThumbnail(Context context, Uri uri) { return getThumbnail(context, uri, getMimeType(context, uri)); } /** * Attempt to retrieve the thumbnail of given Uri from the MediaStore. This * should not be called on the UI thread. * * @param context * @param uri * @param mimeType * @return * @author paulburke */ public static Bitmap getThumbnail(Context context, Uri uri, String mimeType) { if (DEBUG) Log.d(TAG, "Attempting to get thumbnail"); if (!isMediaUri(uri)) { Log.e(TAG, "You can only retrieve thumbnails for images and videos."); return null; } Bitmap bm = null; if (uri != null) { final ContentResolver resolver = context.getContentResolver(); Cursor cursor = null; try { cursor = resolver.query(uri, null, null, null, null); if (cursor.moveToFirst()) { final int id = cursor.getInt(0); if (DEBUG) Log.d(TAG, "Got thumb ID: " + id); if (mimeType.contains("video")) { bm = MediaStore.Video.Thumbnails.getThumbnail(resolver, id, MediaStore.Video.Thumbnails.MINI_KIND, null); } else if (mimeType.contains(FileUtils.MIME_TYPE_IMAGE)) { bm = MediaStore.Images.Thumbnails.getThumbnail(resolver, id, MediaStore.Images.Thumbnails.MINI_KIND, null); } } } catch (Exception e) { if (DEBUG) Log.e(TAG, "getThumbnail", e); } finally { if (cursor != null) cursor.close(); } } return bm; } /** * File and folder comparator. TODO Expose sorting option method * * @author paulburke */ public static Comparator<File> sComparator = new Comparator<File>() { @Override public int compare(File f1, File f2) { // Sort alphabetically by lower case, which is much cleaner return f1.getName().toLowerCase().compareTo(f2.getName().toLowerCase()); } }; /** * File (not directories) filter. * * @author paulburke */ public static FileFilter sFileFilter = new FileFilter() { @Override public boolean accept(File file) { final String fileName = file.getName(); // Return files only (not directories) and skip hidden files return file.isFile() && !fileName.startsWith(HIDDEN_PREFIX); } }; /** * Folder (directories) filter. * * @author paulburke */ public static FileFilter sDirFilter = new FileFilter() { @Override public boolean accept(File file) { final String fileName = file.getName(); // Return directories only and skip hidden directories return file.isDirectory() && !fileName.startsWith(HIDDEN_PREFIX); } }; /** * Get the Intent for selecting content to be used in an Intent Chooser. * * @return The intent for opening a file with Intent.createChooser() * @author paulburke */ public static Intent createGetContentIntent() { // Implicitly allow the user to select a particular kind of data final Intent intent = new Intent(Intent.ACTION_GET_CONTENT); // The MIME data type filter intent.setType("*/*"); // Only return URIs that can be opened with ContentResolver intent.addCategory(Intent.CATEGORY_OPENABLE); return intent; } }