为特定的 YouTube 订阅生成视频上传列表

Question

我正在尝试从我订阅的频道生成视频列表。

import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.services.youtube.YouTube;
import com.google.api.services.youtube.model.PlaylistItemListResponse;
import com.google.api.services.youtube.model.SubscriptionListResponse;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.GeneralSecurityException;
import java.util.Collection;
import java.util.Collections;

public class ApiExample {
    private static final String CLIENT_SECRETS= "client_secret.json";
    private static final Collection<String> SCOPES =
            Collections.singletonList("https://www.googleapis.com/auth/youtube.readonly");

    private static final String APPLICATION_NAME = "Stack Overflow MRE";
    private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();

    /**
     * Create an authorized Credential object.
     *
     * @return an authorized Credential object.
     * @throws IOException in the event that the client_secrets.json file is not found
     */
    public static Credential authorize(final NetHttpTransport httpTransport) throws IOException {
        // Load client secrets.
        InputStream in = ApiExample.class.getResourceAsStream(CLIENT_SECRETS);
        GoogleClientSecrets clientSecrets =
                GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));
        // Build flow and trigger user authorization request.
        GoogleAuthorizationCodeFlow flow =
                new GoogleAuthorizationCodeFlow.Builder(httpTransport, JSON_FACTORY, clientSecrets, SCOPES)
                        .build();
        return new AuthorizationCodeInstalledApp(flow, new LocalServerReceiver()).authorize("user");
    }

    /**
     * Build and return an authorized API client service.
     *
     * @return an authorized API client service
     * @throws GeneralSecurityException, IOException
     */
    public static YouTube getService() throws GeneralSecurityException, IOException {
        final NetHttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
        Credential credential = authorize(httpTransport);
        return new YouTube.Builder(httpTransport, JSON_FACTORY, credential)
                .setApplicationName(APPLICATION_NAME)
                .build();
    }

    /**
     * Call function to create API service object. Define and
     * execute API request. Print API response.
     *
     * @throws GeneralSecurityException, IOException, GoogleJsonResponseException
     */
    public static void main(String[] args)
            throws GeneralSecurityException, IOException {
        YouTube youtubeService = getService();
        // Define and execute the API request
        YouTube.Subscriptions.List request = youtubeService.subscriptions()
                .list("snippet");
        SubscriptionListResponse response = request.setMine(true).setMaxResults(1L).execute();
        String channelId = response.getItems().get(0).getSnippet().getResourceId().getChannelId();

        YouTube.PlaylistItems.List playListRequest = youtubeService.playlistItems().list("snippet");
        PlaylistItemListResponse playlistResponse = playListRequest.setPlaylistId(channelId).execute();
        playlistResponse.getItems().forEach(System.out::println);
    }
}

我已阅读YouTube API to fetch all videos on a channel，但我的问题有点不同，因为我试图从Subscription 而不是Channel 获取视频列表。

我尝试隔离频道 ID，以便按照 video from Google Developers 中有关如何执行此操作的说明进行操作。我用String channelId = response.getItems().get(0).getSnippet().getResourceId().getChannelId();

但是，当我运行上面的代码时，应该以 JSON 表示法从该频道打印出一个视频列表，我看到了这个错误：

Exception in thread "main" com.google.api.client.googleapis.json.GoogleJsonResponseException: 404 Not Found
{
  "code" : 404,
  "errors" : [ {
    "domain" : "youtube.playlistItem",
    "location" : "playlistId",
    "locationType" : "parameter",
    "message" : "The playlist identified with the request's <code>playlistId</code> parameter cannot be found.",
    "reason" : "playlistNotFound"
  } ],
  "message" : "The playlist identified with the request's <code>playlistId</code> parameter cannot be found."
}
    at com.google.api.client.googleapis.json.GoogleJsonResponseException.from(GoogleJsonResponseException.java:150)
    at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:113)
    at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:40)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest$1.interceptResponse(AbstractGoogleClientRequest.java:321)
    at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:1067)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:419)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:352)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:469)
    at ApiExample.main(ApiExample.java:93)

显然，我没有正确隔离频道 ID，否则我误解了视频。从 YouTube 订阅中获取视频的正确方法是什么？

编辑

我的主要方法中的以下更改有效：

public static void main(String[] args)
            throws GeneralSecurityException, IOException {
    YouTube youtubeService = getService();
    // Define and execute the API request
    YouTube.Subscriptions.List request = youtubeService.subscriptions()
            .list("snippet")
    SubscriptionListResponse response = request.setMine(true).setMaxResults(1L).execute();
    String channelId = response.getItems().get(0).getSnippet().getResourceId().getChannelId();

    YouTube.Channels.List channelRequest = youtubeService.channels().list("contentDetails");
    ChannelListResponse channelResponse = channelRequest.setId(channelId).execute();
    String playListID = channelResponse.getItems().get(0).getContentDetails().getRelatedPlaylists().getUploads();

    YouTube.PlaylistItems.List playListRequest = youtubeService.playlistItems().list("snippet");
    PlaylistItemListResponse playlistResponse = playListRequest.setPlaylistId(playListID).execute();
    playlistResponse.getItems().forEach(System.out::println);
}

Answer 1

上面代码的问题归结为以下文档条目：

playlistId（字符串）

playlistId 参数指定要检索其播放列表项的播放列表的唯一 ID。请注意，尽管这是一个可选参数，但每个检索播放列表项的请求都必须为 id 参数或 playlistId 参数指定一个值。

现在应该明白了：playlistId 是播放列表的 ID，因此不能是频道的 ID。

但要列出给定频道的所有上传视频（由其 ID 标识），必须执行以下操作：

调用PlaylistItems.list API 端点，将参数playlistId 设置为该频道的上传播放列表的ID。

通过调用Channels.list 端点并设置参数id 设置为您的频道ID，可以很容易地获得后一个ID。

然后将在端点的 JSON 响应中作为属性值找到上传播放列表 ID：

items[0].contentDetails.relatedPlaylists.uploads.

翻译成Java，这个属性路径会变成下面的getter链，以getUploads结尾：

.getItems().get(0).getContentDetails().getRelatedPlaylists().getUploads().

请注意，对于给定的频道，您只需获取一次上传播放列表 ID，然后就可以随意使用它。

通常，频道 ID 及其对应的上传播放列表 ID 通过s/^UC([0-9a-zA-Z_-]{22})$/UU\1/ 关联。