youtube-api搜索响应(java)

载荷大小：//developers.google.com/youtube/v3/code_samples/java#search_by_keyword

获得以下数据.

{
    "Items": [
        search resource
    ]
}

我想要“NextPageToken”和“PrevPageToken”.
所以我添加了以下代码.

searchResponse.getNextPageToken();

但结果是“无效”;

我错了什么？

参考：ttps：//developers.google.com/youtube/v3/docs/search/list

这是代码.谢谢.

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package com.google.api.services.samples.youtube.cmdline.youtube_cmdline_search_sample;

import com.google.api.client.googleapis.json.GoogleJsonResponseException;
import com.google.api.client.http.HttpRequest;
import com.google.api.client.http.HttpRequestInitializer;
import com.google.api.client.http.HttpTransport;
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.YouTube.Search;
import com.google.api.services.youtube.model.ResourceId;
import com.google.api.services.youtube.model.SearchListResponse;
import com.google.api.services.youtube.model.SearchResult;
import com.google.api.services.youtube.model.Thumbnail;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Iterator;
import java.util.List;
import java.util.Properties;

/**
 * Prints a list of videos based on a search term.
 *
 * @author Jeremy Walker
 */
public class Youtube_sample_2 {

  /** Global instance properties filename. */
  private static String PROPERTIES_FILENAME = "youtube.properties";

  /** Global instance of the HTTP transport. */
  private static final HttpTransport HTTP_TRANSPORT = new NetHttpTransport();

  /** Global instance of the JSON factory. */
  private static final JsonFactory JSON_FACTORY = new JacksonFactory();

  /** Global instance of the max number of videos we want returned (50 = upper limit per page). */
  private static final long NUMBER_OF_VIDEOS_RETURNED = 25;

  /** Global instance of Youtube object to make all API requests. */
  private static YouTube youtube;


  /**
   * Initializes YouTube object to search for videos on YouTube (Youtube.Search.List). The program
   * then prints the names and thumbnails of each of the videos (only first 50 videos).
   *
   * @param args command line args.
   */
  public static void main(String[] args) {
    // Read the developer key from youtube.properties

    Properties properties = new Properties();
    try {
      InputStream in = Search.class.getResourceAsStream("/" + PROPERTIES_FILENAME);
      properties.load(in);
    } catch (IOException e) {
      System.err.println("There was an error reading " + PROPERTIES_FILENAME + ": " + e.getCause()
          + " : " + e.getMessage());
      System.exit(1);
    }
    try {
      /*
       * The YouTube object is used to make all API requests. The last argument is required,but
       * because we don't need anything initialized when the HttpRequest is initialized,we override
       * the interface and provide a no-op function.
       */
      youtube = new YouTube.Builder(HTTP_TRANSPORT,JSON_FACTORY,new HttpRequestInitializer() {
        public void initialize(HttpRequest request) throws IOException {}
      }).setApplicationName("youtube-cmdline-search-sample").build();

      // Get query term from user.
      String queryTerm = getInputQuery();

      YouTube.Search.List search = youtube.search().list("id,snippet");
//      System.out.println(search);

      /*
       * It is important to set your developer key from the Google Developer Console for
       * non-authenticated requests (found under the API Access tab at this link:
       * code.google.com/apis/). This is good practice and increased your quota.
       */
      String apiKey = properties.getProperty("youtube.apikey");

      search.setKey(apiKey);
      search.setQ(queryTerm);
      /*
       * We are only searching for videos (not playlists or channels). If we were searching for
       * more,we would add them as a string like this: "video,playlist,channel".
       */
      search.setType("video");
      /*
       * This method reduces the info returned to only the fields we need and makes calls more
       * efficient.
       */
      search.setFields("items(id/kind,id/videoId,snippet/title,snippet/thumbnails/default/url)");
      search.setMaxResults(NUMBER_OF_VIDEOS_RETURNED);
      SearchListResponse searchResponse = search.execute();
      System.out.println(searchResponse);
//      System.out.println(searchResponse.getNextPageToken());
//      System.out.println(searchResponse.getPageInfo());

      List<SearchResult> searchResultList = searchResponse.getItems();
//      System.out.println(searchResultList);

      if (searchResultList != null) {
        prettyPrint(searchResultList.iterator(),queryTerm);
      }
    } catch (GoogleJsonResponseException e) {
      System.err.println("There was a service error: " + e.getDetails().getCode() + " : "
          + e.getDetails().getMessage());
    } catch (IOException e) {
      System.err.println("There was an IO error: " + e.getCause() + " : " + e.getMessage());
    } catch (Throwable t) {
      t.printStackTrace();
    }
  }

  /*
   * Returns a query term (String) from user via the terminal.
   */
  private static String getInputQuery() throws IOException {

    String inputQuery = "";

    System.out.print("Please enter a search term: ");
    BufferedReader bReader = new BufferedReader(new InputStreamReader(System.in));
    inputQuery = bReader.readLine();

    if (inputQuery.length() < 1) {
      // If nothing is entered,defaults to "YouTube Developers Live."
      inputQuery = "YouTube Developers Live";
    }
    return inputQuery;
  }

  /*
   * Prints out all SearchResults in the Iterator. Each printed line includes title,id,and
   * thumbnail.
   *
   * @param iteratorSearchResults Iterator of SearchResults to print
   *
   * @param query Search query (String)
   */
  private static void prettyPrint(Iterator<SearchResult> iteratorSearchResults,String query) {

    System.out.println("n=============================================================");
    System.out.println(
        "   First " + NUMBER_OF_VIDEOS_RETURNED + " videos for search on "" + query + "".");
    System.out.println("=============================================================n");

    if (!iteratorSearchResults.hasNext()) {
      System.out.println(" There aren't any results for your query.");
    }

    while (iteratorSearchResults.hasNext()) {

      SearchResult singleVideo = iteratorSearchResults.next();
      ResourceId rId = singleVideo.getId();

      // Double checks the kind is video.
      if (rId.getKind().equals("youtube#video")) {
        Thumbnail thumbnail = (Thumbnail) singleVideo.getSnippet().getThumbnails().get("default");

        System.out.println(" Video Id" + rId.getVideoId());
        System.out.println(" Title: " + singleVideo.getSnippet().getTitle());
        System.out.println(" Thumbnail: " + thumbnail.getUrl());
        System.out.println("n-------------------------------------------------------------n");
      }
    }
  }
}

这是文件.

youtube.properties

youtube.apikey = AIzaSyDLnvt0SJRc4hLUWQBiLxkGFLWbsjsRvjQ