最近在做Android TV O的專案，需要在TV 桌面新增自定義頻道/節目，節目的背景圖片要顯示為SD卡或者快取目錄裡面的圖片。

1. 新增自定義頻道
2. 節目背景顯示本地目錄的圖片

一、新增頻道

1. 首先新建頻道、節目實體類，屬性如下。

public class MediaChannel {
    private final String mName;
    private final String mDescription;
    private final String mMediaUri;
    private final String mBgImage;
    private final String mTitle;
    private final String mMediaChannelId;
    private List<MediaProgram> mPrograms;
    private boolean mChannelPublished;
    private long mChannelId;

    MediaChannel(String name, List<MediaProgram> programs, String mediaChannelId) {
        mName = name;
        mTitle = "playlist title";
        mDescription = "playlist description";
        mMediaUri = "dsf";
        mBgImage = "asdf";
        mPrograms = programs;
        mMediaChannelId = mediaChannelId;
    }
    // 省略 set get toString 
 }

public class MediaProgram implements Parcelable {
    private final String mMediaProgramId;
    private final String mContentId;
    private final String mTitle;
    private final String mDescription;
    private final String mBgImageUrl;
    private final String mCardImageUrl;
    private final String mMediaUrl;
    private final String mPreviewMediaUrl;
    private final String mCategory;
    private long mProgramId;
    private int mViewCount;

    MediaProgram(String title, String description, String bgImageUrl, String cardImageUrl,
                 String category, String mediaProgramId, String contentId) {
        mMediaProgramId = mediaProgramId;
        mContentId = contentId;
        mTitle = title;
        mDescription = description;
        mBgImageUrl = bgImageUrl;
        mCardImageUrl = cardImageUrl;
        mMediaUrl = "";
        mPreviewMediaUrl = "";
        mCategory = category;
    }

    // 省略 set get toString 

}
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2. 初始化頻道、節目資訊

private void initChannel() {
        Uri usbUri = getUSBCardImageFileUri();
        Uri pvrUri = getPVRCardImageFileUri();
        grantUriPermissionToApp("com.google.android.tvlauncher", usbUri);
        grantUriPermissionToApp("com.google.android.tvlauncher", pvrUri);

        String bgImageUrl = "";
        String usbCardImageUrl = getUSBCardImageFileUri().toString();
        String pvrCardImageUrl = getPVRCardImageFileUri().toString();
        int mediaProgramId = 1;
        int contentId = 0;

        MediaProgram usbProgram = new MediaProgram("USB", "usb description", bgImageUrl, usbCardImageUrl,
                "USB category", Integer.toString(mediaProgramId), Integer.toString(contentId ++));

        MediaProgram pvrProgram = new MediaProgram("PVR", "pvr description", bgImageUrl, pvrCardImageUrl,
                "PVR category", Integer.toString(mediaProgramId), Integer.toString(contentId ++));
        List<MediaProgram> programs = new ArrayList<>();
        programs.add(usbProgram);
        programs.add(pvrProgram);

        mChannelId = LocalDataManager.getChannelId(this);
        mChannel = new MediaChannel("MediaChannel", programs, Long.toString(mChannelId));
}

    private Uri getUSBCardImageFileUri() {
        String sdPath = Environment.getExternalStorageDirectory().getPath();
        File file = new File(sdPath + "/Pictures/mediachannel/usb_thumbnail.jpg");
        Uri uri = FileProvider.getUriForFile(this, "com.rogera.mediaplaychannel.fileprovider", file);
        Log.v(TAG, "uri:" + uri.toString());
        return uri;
    }

    private Uri getPVRCardImageFileUri() {
        String sdPath = Environment.getExternalStorageDirectory().getPath();
        File file = new File(sdPath + "/Pictures/mediachannel/pvr_thumbnail.jpg");
        Uri uri = FileProvider.getUriForFile(this, "com.rogera.mediaplaychannel.fileprovider", file);
        Log.v(TAG, "uri:" + uri.toString());
        return uri;
    }

    private void grantUriPermissionToApp(String packageName, Uri uri) {
        grantUriPermission(packageName, uri, Intent.FLAG_GRANT_READ_URI_PERMISSION
                | Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
    }
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3.新增頻道、節目

mChannelId = MediaTVProvider.addChannel(MainActivity.this, mChannel);
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mChannel 為initChannel() 方法裡面初始化的實體類

貼出核心類MediaTVProvider.java

package com.rogera.mediaplaychannel;

import android.content.ComponentName;
import android.content.ContentUris;
import android.content.Context;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.support.annotation.DrawableRes;
import android.support.annotation.WorkerThread;
import android.support.media.tv.Channel;
import android.support.media.tv.ChannelLogoUtils;
import android.support.media.tv.PreviewProgram;
import android.support.media.tv.TvContractCompat;
import android.text.TextUtils;
import android.util.Log;

import java.util.List;


/**
 * Created by rogera on 2017/12/30.
 */
public class MediaTVProvider {

    private static final String TAG = "MediaTVProvider";

    private static final String SCHEME = "tvmediachannels";
    private static final String APPS_LAUNCH_HOST = "com.google.android.tvmediachannels";
    private static final String PLAY_MEDIA_ACTION_PATH = "playMedia";
    private static final String START_APP_ACTION_PATH = "startApp";

    private static final Uri PREVIEW_PROGRAMS_CONTENT_URI =
            Uri.parse("content://android.media.tv/preview_program");

    static private String createInputId(Context context) {
        ComponentName cName = new ComponentName(context, MainActivity.class.getName());
        return TvContractCompat.buildInputId(cName);
    }

    @WorkerThread
    static long addChannel(Context context, MediaChannel mediaChannel) {
        String channelInputId = createInputId(context);
        Channel channel = new Channel.Builder()
                .setDisplayName(mediaChannel.getName())
                .setDescription(mediaChannel.getDescription())
                .setType(TvContractCompat.Channels.TYPE_PREVIEW)
                .setInputId(channelInputId)
                .setAppLinkIntentUri(Uri.parse(SCHEME + "://" + APPS_LAUNCH_HOST
                        + "/" + START_APP_ACTION_PATH))
                .setInternalProviderId(mediaChannel.getMediaChannelId())
                .build();

        Uri channelUri = context.getContentResolver().insert(TvContractCompat.Channels.CONTENT_URI,
                channel.toContentValues());
        if (channelUri == null || channelUri.equals(Uri.EMPTY)) {
            Log.e(TAG, "addChannel Insert channel failed");
            return 0;
        }
        long channelId = ContentUris.parseId(channelUri);
        mediaChannel.setChannelPublishedId(channelId);

        writeChannelLogo(context, channelId, R.drawable.media_logo);

        List<MediaProgram> programs = mediaChannel.getMediaPrograms();

        int weight = programs.size();
        for (int i = 0; i < programs.size(); ++i, --weight) {
            MediaProgram mp = programs.get(i);
            final String mediaProgramId = mp.getMediaProgramId();
            final String contentId = mp.getContentId();

            PreviewProgram program = new PreviewProgram.Builder()
                    .setChannelId(channelId)
                    .setTitle(mp.getTitle())
                    .setDescription(mp.getDescription())
                    .setPosterArtUri(Uri.parse(mp.getCardImageUrl()))
                    .setIntentUri(Uri.parse(SCHEME + "://" + APPS_LAUNCH_HOST
                            + "/" + PLAY_MEDIA_ACTION_PATH + "/" + mediaProgramId))
                    //.setPreviewVideoUri(Uri.parse(mp.getPreviewMediaUrl()))
                    .setInternalProviderId(mediaProgramId)
                    .setContentId(contentId)
                    .setWeight(weight)
                    .setType(TvContractCompat.PreviewPrograms.TYPE_CLIP)
                    .build();

            Uri programUri = context.getContentResolver().insert(PREVIEW_PROGRAMS_CONTENT_URI,
                    program.toContentValues());
            if (programUri == null || programUri.equals(Uri.EMPTY)) {
                Log.e(TAG, "addChannel Insert program failed");
            } else {
                mp.setProgramId(ContentUris.parseId(programUri));
            }
        }
        return channelId;
    }

    @WorkerThread
    static void deleteChannel(Context context, long channelId) {
        int rowsDeleted = context.getContentResolver().delete(
                TvContractCompat.buildChannelUri(channelId), null, null);
        if (rowsDeleted < 1) {
            Log.e(TAG, "Delete channel failed");
        }
    }

    @WorkerThread
    public static void deleteProgram(Context context, MediaProgram program) {
        deleteProgram(context, program.getProgramId());
    }

    @WorkerThread
    static void deleteProgram(Context context, long programId) {
        int rowsDeleted = context.getContentResolver().delete(
                TvContractCompat.buildPreviewProgramUri(programId), null, null);
        if (rowsDeleted < 1) {
            Log.e(TAG, "Delete program failed");
        }
    }

    /**
     * Writes a drawable as the channel logo.
     *
     * @param channelId  identifies the channel to write the logo.
     * @param drawableId resource to write as the channel logo. This must be a bitmap and not, say
     *                   a vector drawable.
     */
    @WorkerThread
    static private void writeChannelLogo(Context context, long channelId,
                                         @DrawableRes int drawableId) {
        Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(), drawableId);
        ChannelLogoUtils.storeChannelLogo(context, channelId, bitmap);
    }

    @WorkerThread
    static void updateMediaProgram(Context context, MediaProgram mediaProgram) {
        long programId = mediaProgram.getProgramId();
        Uri programUri = TvContractCompat.buildPreviewProgramUri(programId);
        try (Cursor cursor = context.getContentResolver().query(programUri, null, null, null,
                null)) {
            if (!cursor.moveToFirst()) {
                Log.e(TAG, "Update program failed");
            }
            PreviewProgram porgram = PreviewProgram.fromCursor(cursor);
            PreviewProgram.Builder builder = new PreviewProgram.Builder(porgram)
                    .setTitle(mediaProgram.getTitle());

            int rowsUpdated = context.getContentResolver().update(programUri,
                    builder.build().toContentValues(), null, null);
            if (rowsUpdated < 1) {
                Log.e(TAG, "Update program failed");
            }
        }
    }

    static void publishProgram(Context context, MediaProgram mediaProgram, long channelId, int weight) {
        final String mediaProgramId = mediaProgram.getMediaProgramId();

        PreviewProgram program = new PreviewProgram.Builder()
                .setChannelId(channelId)
                .setTitle(mediaProgram.getTitle())
                .setDescription(mediaProgram.getDescription())
                .setPosterArtUri(Uri.parse(mediaProgram.getCardImageUrl()))
                .setIntentUri(Uri.parse(SCHEME + "://" + APPS_LAUNCH_HOST
                        + "/" + PLAY_MEDIA_ACTION_PATH + "/" + mediaProgramId))
                .setPreviewVideoUri(Uri.parse(mediaProgram.getPreviewMediaUrl()))
                .setInternalProviderId(mediaProgramId)
                .setWeight(weight)
                .setType(TvContractCompat.PreviewPrograms.TYPE_MOVIE)
                .build();

        Uri programUri = context.getContentResolver().insert(PREVIEW_PROGRAMS_CONTENT_URI,
                program.toContentValues());
        if (programUri == null || programUri.equals(Uri.EMPTY)) {
            Log.e(TAG, "Insert program failed");
            return;
        }
        mediaProgram.setProgramId(ContentUris.parseId(programUri));
    }

    @WorkerThread
    static void setProgramViewCount(Context context, long programId, int numberOfViews) {
        Uri programUri = TvContractCompat.buildPreviewProgramUri(programId);
        try (Cursor cursor = context.getContentResolver().query(programUri, null, null, null,
                null)) {
            if (!cursor.moveToFirst()) {
                return;
            }
            PreviewProgram existingProgram = PreviewProgram.fromCursor(cursor);
            PreviewProgram.Builder builder = new PreviewProgram.Builder(existingProgram)
                    .setInteractionCount(numberOfViews)
                    .setInteractionType(TvContractCompat.PreviewProgramColumns
                            .INTERACTION_TYPE_VIEWS);
            int rowsUpdated = context.getContentResolver().update(
                    TvContractCompat.buildPreviewProgramUri(programId),
                    builder.build().toContentValues(), null, null);
            if (rowsUpdated != 1) {
                Log.e(TAG, "Update program failed");
            }
        }
    }
}
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二、節目背景顯示本地目錄的圖片

對於顯示本地圖片，需要使用FileProvider 獲取圖片檔案的uri然後設定給節目。如果使用 Uri.fromFile(new File(filePath) 這種方式，就會報Permission問題: class java.io.FileNotFoundException: /storage/emulated/0/Pictures/mediachannel/usb_thumbnail.jpg (Permission denied)

使用FileProvider分享檔案給其他應用需要給對應的應用賦予讀許可權，可以通過如下兩種方式：

 intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
 grantUriPermissionToApp("com.google.android.tvlauncher", usbUri);
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這裡只能使用第二種方式了。com.google.android.tvlauncher 為TV launcher的包名。

1. 使用FileProvider首先需要在AndroidManifest.xml 節點下申明

    <provider
        android:name="android.support.v4.content.FileProvider"
        android:authorities="com.rogera.mediaplaychannel.fileprovider"
        android:grantUriPermissions="true"
        android:exported="false">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/filepaths" />
    </provider>
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2. 在res下xml資料夾下新建filepaths.xml

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <external-path path="Pictures" name="pictures" />
</paths>
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3. 獲取檔案URI

File file = new File(sdPath + "/Pictures/mediachannel/usb_thumbnail.jpg");
Uri uri = FileProvider.getUriForFile(this, "com.rogera.mediaplaychannel.fileprovider", file);
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三、其他說明

1、sdcard裡面的檔案是push進去的，是假設應用獲取U盤裡面的電影/圖片/音樂 生成的縮圖。點選桌面的usb節目就會播放相應的電影/圖片/音樂。

2. 在桌面新增頻道、節目需要申請EPG許可權，SD需要申請storage許可權

<uses-permission android:name="com.android.providers.tv.permission.WRITE_EPG_DATA" />
<uses-permission android:name="com.android.providers.tv.permission.READ_EPG_DATA" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
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3. 同時需要在gradle新增如下依賴

implementation 'com.android.support:leanback-v17:26.1.0'
implementation 'com.android.support:support-tv-provider:26.1.0'
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4. 上圖啦

Google官方參考：https://developer.android.google.cn/training/tv/tif/channel.html#update