Android功能集锦（2017.8）

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1.通过Uri获取文件完整路径
/**     * 获取Uri对应的文件的路径。  4.4之后需增加权限  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />     */    public static String getPath(Context context, Uri uri) {        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT && DocumentsContract.isDocumentUri(context, uri)) { // 【DocumentProvider】            if (isExternalStorageDocument(uri)) { // 【ExternalStorageProvider】                String docId = DocumentsContract.getDocumentId(uri);                String[] split = docId.split(":");                String type = split[0];//                if ("primary".equalsIgnoreCase(type))                return Environment.getExternalStorageDirectory() + "/" + split[1];            } else if (isDownloadsDocument(uri)) { // 【DownloadsProvider】                String id = DocumentsContract.getDocumentId(uri);                Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));                return getDataColumn(context, contentUri, null, null);            } else if (isMediaDocument(uri)) { // 【MediaProvider】                String docId = DocumentsContract.getDocumentId(uri);                String[] split = docId.split(":");                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;                String selection = "_id=?";                String[] selectionArgs = new String[]{split[1]};                return getDataColumn(context, contentUri, selection, selectionArgs);            }        } else if ("content".equalsIgnoreCase(uri.getScheme())) { // 【MediaStore (and general)】            return getDataColumn(context, uri, null, null);        } else if ("file".equalsIgnoreCase(uri.getScheme())) { // 【File】            return uri.getPath();        }        return null;    }    /**     * 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.     */    public static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {        Cursor cursor = null;        String column = "_data";        String[] projection = {column};        try {            cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);            if (cursor != null && cursor.moveToFirst()) {                int column_index = cursor.getColumnIndexOrThrow(column);                return cursor.getString(column_index);            }        } finally {            if (cursor != null) cursor.close();        }        return null;    }    /**     * @param uri The Uri to check.     * @return Whether the Uri authority is ExternalStorageProvider.     */    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.     */    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.     */    public static boolean isMediaDocument(Uri uri) {        return "com.android.providers.media.documents".equals(uri.getAuthority());    }
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