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MediaBrowserService / src / com.example.android.mediabrowserservice / utils /

MediaIDHelper.java

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/*
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 * Copyright (C) 2014 The Android Open Source Project
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *      http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 */
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package com.example.android.mediabrowserservice.utils;
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import java.util.Arrays;
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/**
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 * Utility class to help on queue related tasks.
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 */
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public class MediaIDHelper {
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    private static final String TAG = LogHelper.makeLogTag(MediaIDHelper.class);
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    // Media IDs used on browseable items of MediaBrowser
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    public static final String MEDIA_ID_ROOT = "__ROOT__";
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    public static final String MEDIA_ID_MUSICS_BY_GENRE = "__BY_GENRE__";
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    public static final String MEDIA_ID_MUSICS_BY_SEARCH = "__BY_SEARCH__";
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    private static final char CATEGORY_SEPARATOR = '/';
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    private static final char LEAF_SEPARATOR = '|';
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    public static String createMediaID(String musicID, String... categories) {
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        // MediaIDs are of the form <categoryType>/<categoryValue>|<musicUniqueId>, to make it easy
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        // to find the category (like genre) that a music was selected from, so we
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        // can correctly build the playing queue. This is specially useful when
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        // one music can appear in more than one list, like "by genre -> genre_1"
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        // and "by artist -> artist_1".
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        StringBuilder sb = new StringBuilder();
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        if (categories != null && categories.length > 0) {
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            sb.append(categories[0]);
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            for (int i=1; i < categories.length; i++) {
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                sb.append(CATEGORY_SEPARATOR).append(categories[i]);
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            }
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        }
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        if (musicID != null) {
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            sb.append(LEAF_SEPARATOR).append(musicID);
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        }
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        return sb.toString();
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    }
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    public static String createBrowseCategoryMediaID(String categoryType, String categoryValue) {
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        return categoryType + CATEGORY_SEPARATOR + categoryValue;
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    }
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    /**
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     * Extracts unique musicID from the mediaID. mediaID is, by this sample's convention, a
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     * concatenation of category (eg "by_genre"), categoryValue (eg "Classical") and unique
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     * musicID. This is necessary so we know where the user selected the music from, when the music
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     * exists in more than one music list, and thus we are able to correctly build the playing queue.
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     *
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     * @param mediaID that contains the musicID
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     * @return musicID
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     */
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    public static String extractMusicIDFromMediaID(String mediaID) {
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        int pos = mediaID.indexOf(LEAF_SEPARATOR);
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        if (pos >= 0) {
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            return mediaID.substring(pos+1);
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        }
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        return null;
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    }
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    /**
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     * Extracts category and categoryValue from the mediaID. mediaID is, by this sample's
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     * convention, a concatenation of category (eg "by_genre"), categoryValue (eg "Classical") and
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     * mediaID. This is necessary so we know where the user selected the music from, when the music
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     * exists in more than one music list, and thus we are able to correctly build the playing queue.
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     *
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     * @param mediaID that contains a category and categoryValue.
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     */
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    public static String[] getHierarchy(String mediaID) {
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        int pos = mediaID.indexOf(LEAF_SEPARATOR);
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        if (pos >= 0) {
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            mediaID = mediaID.substring(0, pos);
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        }
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        return mediaID.split(String.valueOf(CATEGORY_SEPARATOR));
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    }
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    public static String extractBrowseCategoryValueFromMediaID(String mediaID) {
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        String[] hierarchy = getHierarchy(mediaID);
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        if (hierarchy != null && hierarchy.length == 2) {
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            return hierarchy[1];
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        }
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        return null;
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    }
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    private static boolean isBrowseable(String mediaID) {
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        return mediaID.indexOf(LEAF_SEPARATOR) < 0;
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    }
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    public static String getParentMediaID(String mediaID) {
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        String[] hierarchy = getHierarchy(mediaID);
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        if (!isBrowseable(mediaID)) {
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            return createMediaID(null, hierarchy);
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        }
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        if (hierarchy == null || hierarchy.length <= 1) {
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            return MEDIA_ID_ROOT;
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        }
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        String[] parentHierarchy = Arrays.copyOf(hierarchy, hierarchy.length-1);
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        return createMediaID(null, parentHierarchy);
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    }
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}
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