如何在android中使用youtube api从播放列表中提取所有视频缩略图？

Question

让我们看下面的例子。

在这里我可以在 imageView 中看到 youTubeThumbnailView1 的缩略图。

我在代码中包含了一些问题作为 cmets 的一部分。

一开始我以为我可以创建一个 ImageView 的 ArrayList 并在其中获取所有缩略图，但这不起作用，因为我什至无法访问该方法之外的 imageView。

感谢任何帮助。

public class MainActivity extends YouTubeBaseActivity implements YouTubeThumbnailView.OnInitializedListener {

    private YouTubeThumbnailView youTubeThumbnailView1;
    //private YouTubeThumbnailLoader youTubeThumbnailLoader;
    private ImageView imageView;

    @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            youTubeThumbnailView1 = (YouTubeThumbnailView) findViewById(R.id.youtubeThumbnailView1);
            imageView = (ImageView) findViewById(R.id.imageView);
            youTubeThumbnailView1.initialize(DeveloperKey.DEVELOPER_KEY, this);

            //Accessing imageView here would give NullPointerException
        }

    @Override
        public void onInitializationSuccess(YouTubeThumbnailView youTubeThumbnailView, YouTubeThumbnailLoader youTubeThumbnailLoader) {

        //this.youTubeThumbnailLoader = youTubeThumbnailLoader; for calling next() etc. in onThumbnailLoader(,)

        youTubeThumbnailLoader.setOnThumbnailLoadedListener(new ThumbnailListener());
        youTubeThumbnailLoader.setPlaylist("ECAE6B03CA849AD332",1);

        //How to call release() on the youTubeThumbnailLoader parameter as it causes ServiceConnectionLeaked after exiting the app. But if you call it here nothing works.
        }

    @Override
        public void onInitializationFailure(YouTubeThumbnailView youTubeThumbnailView, YouTubeInitializationResult youTubeInitializationResult) {
    }

    private class ThumbnailListener implements YouTubeThumbnailLoader.OnThumbnailLoadedListener{

            @Override
            public void onThumbnailLoaded(YouTubeThumbnailView youTubeThumbnailView, String s) {
                imageView.setImageDrawable(youTubeThumbnailView.getDrawable());

            /*How can i access this imageView outside of this method?
              Using something like below will show all the thumbnails BUT how do you access them outside of this method?

            if (youTubeThumbnailLoader.hasNext()) {
               youTubeThumbnailLoader.next();
            } else {
              youTubeThumbnailLoader.first();
            }
            */

            }

            @Override
            public void onThumbnailError(YouTubeThumbnailView youTubeThumbnailView, YouTubeThumbnailLoader.ErrorReason errorReason) {
            }
        }
    }

Answer 1

我最近设法在名为 picasso 的库的帮助下将图像加载到 imageview 和 android async http 以检索缩略图列表。 将此添加到依赖项下的应用级 build.gradle 文件中。

dependencies {
compile 'com.squareup.picasso:picasso:2.5.2'
compile 'com.loopj.android:android-async-http:1.4.9'
}

为了检索图像，我向 Youtube 数据 API 发出了一个 http get 请求，并检索了所有图像 URL 并将其添加为 Video 类的缩略图属性。 有关检索所有缩略图的更多信息：https://developers.google.com/youtube/v3/docs/playlistItems/list

我是这样做的。

 private void loadVideos(String id) {
    //just a method to check if i am connected to the internet
    checkConnected();
    String requestUrl = "https://www.googleapis.com/youtube/v3/playlistItems";
    String key = API_KEY;
    String param = "?part=id, snippet&playlistId=" + id + "&key=" + key + "&maxResults=50";
    String request = requestUrl + param;

    AsyncHttpClient client = new AsyncHttpClient();
    RequestParams params = new RequestParams();
    client.get(request, params, new TextHttpResponseHandler() {
        @Override
        public void onFailure(int statusCode, Header[] headers, String responseString, Throwable throwable) {

        }

        @Override
        public void onSuccess(int statusCode, Header[] headers, String responseString) {
            try {
                videoArr = new ArrayList<Video>();
                JSONObject obj = new JSONObject(responseString);
                JSONArray playlistItems = obj.getJSONArray("items");
                for (int i = 0; i < playlistItems.length(); i++) {
                    JSONObject snippet = playlistItems.getJSONObject(i).getJSONObject("snippet");
                    String title = snippet.getString("title");
                    String description = snippet.getString("description");

                    JSONObject thumbnailObj = snippet.getJSONObject("thumbnails");
                    //Here i am extracting the URL of the thumbnail
                    String thumbnail = thumbnailObj.getJSONObject("high").getString("url");

                    JSONObject resourceId = snippet.getJSONObject("resourceId");
                    String id = resourceId.getString("videoId");

                    Video video = new Video(id, title, description, thumbnail);
                    videoArr.add(video);
                }
                populateListView(videoArr);
            } catch (JSONException e) {
                e.printStackTrace();
            }
        }
    });
}

我的视频类如下：

public class Video implements Serializable {
    private String id;
    private String title;
    private String description;
    private String thumbnail;

    public Video(String id, String title, String description, String thumbnail) {
        this.id = id;
        this.title = title;
        this.description = description;
        this.thumbnail = thumbnail;
    }

    public String getId() {
        return id;
    }

    public String getTitle() {
        return title;
    }

    public String getDescription() {
        return description;
    }

    public String getThumbnail() {
        return thumbnail;
    }
}

最后，为了加载图像，我使用毕加索这样做了。

ImageView yourImageView = (ImageView)findViewById(R.id.yourImageView);

//video is my Video object.
Picasso.with(yourActivity.this).load(video.getThumbnail()).fit().into(yourImageView);

别忘了你必须从开发者控制台获取 API 密钥。希望我能帮上忙。祝你的应用好运！