Android - obb拓展文件

Opaque Binary Blob，简称obb，为apk的拓展文件，下载的资源可以是视频，图片，资源等，常见于VR或者游戏中使用。

拓展文件大小不能超过2GB，格式可以是任意格式，可压缩，最多可以添加1-2个拓展文件。从概念上讲，每个拓展文件扮演者不同的角色

• 主扩展（main）：应用必须的额外资源
• 布丁扩展：用于更新

https://developer.android.com/google/play/expansion-files

文件格式

用户上传的文件，最终会被更改为oob格式

[main|patch].versionCode.packageName.obb

举例：main.314159.com.example.app.obb

存储位置

api：getObbDir()

实际位置：/sdcard/Android/obb//

下载

下载library

复制下载的资源到我们项目

market_apk_expansion/downloader_library:下载资源

market_apk_expansion/zip_file: zip操作

market_licensing/library：licensing

• 下载服务

  public class SampleDownloaderService extends DownloaderService {
      // You must use the public key belonging to your publisher account
      public static final String BASE64_PUBLIC_KEY = "YourLVLKey";
      // You should also modify this salt
      public static final byte[] SALT = new byte[] { 1, 42, -12, -1, 54, 98,
              -100, -12, 43, 2, -8, -4, 9, 5, -106, -107, -33, 45, -1, 84
      };
  
      @Override
      public String getPublicKey() {
          return BASE64_PUBLIC_KEY;
      }
  
      @Override
      public byte[] getSALT() {
          return SALT;
      }
  
      @Override
      public String getAlarmReceiverClassName() {
          return SampleAlarmReceiver.class.getName();
      }
  }

• 实施警报接收程序

public class SampleAlarmReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        try {
            DownloaderClientMarshaller.startDownloadServiceIfRequired(context,
                intent, SampleDownloaderService.class);
        } catch (NameNotFoundException e) {
            e.printStackTrace();
        }
    }
}

• 下载

@Override
public void onCreate(Bundle savedInstanceState) {
    // Check if expansion files are available before going any further
    if (!expansionFilesDelivered()) {
        // Build an Intent to start this activity from the Notification
        Intent notifierIntent = new Intent(this, MainActivity.getClass());
        notifierIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK |
                                Intent.FLAG_ACTIVITY_CLEAR_TOP);
        ...
        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0,
                notifierIntent, PendingIntent.FLAG_UPDATE_CURRENT);

        // Start the download service (if required)
        int startResult =
            DownloaderClientMarshaller.startDownloadServiceIfRequired(this,
                        pendingIntent, SampleDownloaderService.class);
        // If download has started, initialize this activity to show
        // download progress
        if (startResult != DownloaderClientMarshaller.NO_DOWNLOAD_REQUIRED) {
            // This is where you do set up to display the download
            // progress (next step)
            ...
            return;
        } // If the download wasn't necessary, fall through to start the app
    }
    startApp(); // Expansion files are available, start the app
}


boolean expansionFilesDelivered() {
    for (XAPKFile xf : xAPKS) {
        String fileName = Helpers.getExpansionAPKFileName(this, xf.isBase,
            xf.fileVersion);
        if (!Helpers.doesFileExist(this, fileName, xf.fileSize, false))
            return false;
    }
    return true;
}

• 读取

// The shared path to all app expansion files
private final static String EXP_PATH = "/Android/obb/";

static String[] getAPKExpansionFiles(Context ctx, int mainVersion,
      int patchVersion) {
    String packageName = ctx.getPackageName();
    Vector<String> ret = new Vector<String>();
    if (Environment.getExternalStorageState()
          .equals(Environment.MEDIA_MOUNTED)) {
        // Build the full path to the app's expansion files
        File root = Environment.getExternalStorageDirectory();
        File expPath = new File(root.toString() + EXP_PATH + packageName);

        // Check that expansion file path exists
        if (expPath.exists()) {
            if ( mainVersion > 0 ) {
                String strMainPath = expPath + File.separator + "main." +
                        mainVersion + "." + packageName + ".obb";
                File main = new File(strMainPath);
                if ( main.isFile() ) {
                        ret.add(strMainPath);
                }
            }
            if ( patchVersion > 0 ) {
                String strPatchPath = expPath + File.separator + "patch." +
                        mainVersion + "." + packageName + ".obb";
                File main = new File(strPatchPath);
                if ( main.isFile() ) {
                        ret.add(strPatchPath);
                }
            }
        }
    }
    String[] retArray = new String[ret.size()];
    ret.toArray(retArray);
    return retArray;
}

• zip读取，上面zip_file中api

// Get a ZipResourceFile representing a merger of both the main and patch files
ZipResourceFile expansionFile =
    APKExpansionSupport.getAPKExpansionZipFile(appContext,
        mainVersion, patchVersion);

// Get an input stream for a known file inside the expansion file ZIPs
InputStream fileStream = expansionFile.getInputStream(pathToFileInsideZip);

测试

打包（jobb命令 ）

参考：https://developer.android.com/studio/command-line/jobb

测试

可以手动复制到/sdcard/Android/obb/{package}目录运行测试