android - 强制 Android 的 Drive API 仅在在线模式下工作

Question

最近，我刚刚设法将 Drive API 相关代码从 Google APIs Client Library for Java 迁移到 Google Play services client library

以下代码是在 appdata 文件夹中搜索一个文件，然后将其下载为临时文件。

private static GoogleCloudFile searchFromGoogleDrive(GoogleApiClient googleApiClient, HandleStatusable h, PublishProgressable p) {
    DriveFolder driveFolder = Drive.DriveApi.getAppFolder(googleApiClient);

    final String titleName = ("my-title");
    Query query = new Query.Builder()
            .addFilter(Filters.and(
                Filters.contains(SearchableField.TITLE, titleName),
                Filters.eq(SearchableField.TRASHED, false)
            ))
            .build();

    DriveApi.MetadataBufferResult metadataBufferResult = driveFolder.queryChildren(googleApiClient, query).await();

    if (metadataBufferResult == null) {
        return null;
    }

    Status status = metadataBufferResult.getStatus();

    if (!status.isSuccess()) {
        h.handleStatus(status);
        return null;
    }

    MetadataBuffer metadataBuffer = null;
    boolean needToReleaseMetadataBuffer = true;

    try {
        metadataBuffer = metadataBufferResult.getMetadataBuffer();
        if (metadataBuffer != null ) {
            long checksum = 0;
            long date = 0;
            int version = 0;
            Metadata metadata = null;

            for (Metadata md : metadataBuffer) {
                if (p.isCancelled()) {
                    return null;
                }

                if (md == null || !md.isDataValid()) {
                    continue;
                }

                final String title = md.getTitle();

                // ...

                metadata = md;

                break;

            }   // for

            if (metadata != null) {
                // Caller will be responsible to release the resource. If release too early,
                // metadata will not readable.
                needToReleaseMetadataBuffer = false;
                return GoogleCloudFile.newInstance(metadataBuffer, metadata, checksum, date, version);
            }
        }   // if
    } finally {
        if (needToReleaseMetadataBuffer) {
            if (metadataBuffer != null) {
                metadataBuffer.release();
            }
        }
    }

    return null;
}

public static CloudFile loadFromGoogleDrive(GoogleApiClient googleApiClient, HandleStatusable h, PublishProgressable p) {
    final java.io.File directory = ...

    GoogleCloudFile googleCloudFile = searchFromGoogleDrive(googleApiClient, h, p);

    if (googleCloudFile == null) {
        return null;
    }

    try {
        DriveFile driveFile = googleCloudFile.metadata.getDriveId().asDriveFile();
        DriveApi.DriveContentsResult driveContentsResult = driveFile.open(googleApiClient, DriveFile.MODE_READ_ONLY, null).await();

        if (driveContentsResult == null) {
            return null;
        }

        Status status = driveContentsResult.getStatus();
        if (!status.isSuccess()) {
            h.handleStatus(status);
            return null;
        }

        final long checksum = googleCloudFile.checksum;
        final long date = googleCloudFile.date;
        final int version = googleCloudFile.version;

        p.publishProgress(MyApplication.instance().getString(R.string.downloading));

        final DriveContents driveContents = driveContentsResult.getDriveContents();

        InputStream inputStream = null;
        java.io.File outputFile = null;
        OutputStream outputStream = null;

        try {
            inputStream = driveContents.getInputStream();
            outputFile = java.io.File.createTempFile("me", ".zip", directory);
            outputFile.deleteOnExit();
            outputStream = new FileOutputStream(outputFile);

            int read = 0;
            byte[] bytes = new byte[1024];

            while ((read = inputStream.read(bytes)) != -1) {
                outputStream.write(bytes, 0, read);
            }
        } catch (IOException ex) {
            Log.e(TAG, "", ex);
        } finally {
            org.yccheok.file.Utils.close(outputStream);
            org.yccheok.file.Utils.close(inputStream);
            driveContents.discard(googleApiClient);
        }

        if (outputFile == null) {
            return null;
        }

        return CloudFile.newInstance(outputFile, checksum, date, version);
    } finally {
        googleCloudFile.metadataBuffer.release();
    }
}

以前，当我使用 Java 版 Google API 客户端库时，如果没有互联网连接，类似的代码只会抛出异常。

但是，当我使用 Google Play 服务客户端库时，上面的代码仍然可以成功运行，即使我的设备处于飞行模式并关闭了 wifi。 em>

Google Play 服务客户端库 中的 Drive API 似乎能够在没有互联网连接时读取离线文件。

有没有办法，在没有互联网连接的情况下，执行上述代码会失败？因为，我想避免让我的用户下载过时的云文件的风险。

Answer 1

无法按照您的要求强制失败。

您可以做的是在查询之前请求与服务器同步:https://developers.google.com/android/reference/com/google/android/gms/drive/DriveApi.html#requestSync(com.google.android.gms.common.api.GoogleApiClient)

如果没有连接，同步将因网络错误而失败。