Searching by keyword

The process of searching for videos by keyword is adapted from https://developers.google.com/youtube/v3/code_samples/java#search_by_keyword. Other potentially useful code examples can be found at https://developers.google.com/youtube/v3/code_samples/java. The process has been simplified so that we can focus on the search process. We start with a try block and the creation of a YouTube instance. This class provides the basic access to the API. Javadocs for this API is found at https://developers.google.com/resources/api-libraries/documentation/youtube/v3/java/latest/.

The YouTube.Builder class is used to construct a YouTube instance. Its constructor takes three arguments:

• Transport: Object used for HTTP
• JSONFactory: Used to process JSON objects
• HttpRequestInitializer: None is needed for this example

Many of the APIs responses will be in the form of JSON objects. The YouTube class' setApplicationName method gives it a name and the build method creates a new YouTube instance:

    try { 
        YouTube youtube = new YouTube.Builder( 
            Auth.HTTP_TRANSPORT, 
            Auth.JSON_FACTORY, 
            new HttpRequestInitializer() { 
                public void initialize(HttpRequest request)  
                        throws IOException { 
                } 
            }) 
                .setApplicationName("application_name") 
        ... 
    } catch (GoogleJSONResponseException ex) { 
        // Handle exceptions 
    } catch (IOException ex) { 
        // Handle exceptions 
    } 

Next, we initialize a string to hold the search term of interest. In this case, we will look for videos containing the word cats:

    String queryTerm = "cats"; 

The class, YouTube.Search.List, maintains a collection of search results. The YouTube class's search method specifies the type of resource to be returned. In this case, the string specifies the id and snippet portions of the search result to be returned:

    YouTube.Search.List search = youtube 
        .search() 
        .list("id,snippet"); 

The search result is a JSON object that has the following structure. It is described in more detail at https://developers.google.com/youtube/v3/docs/playlistItems#methods. In the previous sequence, only the id and snippet parts of a search will be returned, resulting in a more efficient operation:

{ 
  "kind": "youtube#searchResult", 
  "etag": etag, 
  "id": { 
    "kind": string, 
    "videoId": string, 
    "channelId": string, 
    "playlistId": string 
  }, 
  "snippet": { 
    "publishedAt": datetime, 
    "channelId": string, 
    "title": string, 
    "description": string, 
    "thumbnails": { 
      (key): { 
        "url": string, 
        "width": unsigned integer, 
        "height": unsigned integer 
      } 
    }, 
    "channelTitle": string, 
    "liveBroadcastContent": string 
  } 
} 

Next, we need to specify the API key and various search parameters. The query term is specified, as well as the type of media to be returned. In this case, only videos will be returned. The other two options include channel and playlist:

    String apiKey = "Your API key"; 
    search.setKey(apiKey); 
    search.setQ(queryTerm); 
    search.setType("video"); 

In addition, we further specify the fields to be returned as shown here. These correspond to fields of the JSON object:

    search.setFields("items(id/kind,id/videoId,snippet/title," +  
        "snippet/description,snippet/thumbnails/default/url)"); 

We also specify the maximum number of results to retrieve using the setMaxResults method:

    search.setMaxResults(10L); 

The execute method will perform the actual query, returning a SearchListResponse object. Its getItems method returns a list of SearchResult objects, one for each video retrieved:

    SearchListResponse searchResponse = search.execute(); 
    List<SearchResult> searchResultList =  
        searchResponse.getItems(); 

In this example, we do not iterate through each video returned. Instead, we retrieve the first video and display information about the video. The SearchResult video variable allows us to access different parts of the JSON object, as shown here:

    SearchResult video = searchResultList.iterator().next(); 
    Thumbnail thumbnail = video 
        .getSnippet().getThumbnails().getDefault(); 

    out.println("Kind: " + video.getKind()); 
    out.println("Video Id: " + video.getId().getVideoId()); 
    out.println("Title: " + video.getSnippet().getTitle()); 
    out.println("Description: " +  
        video.getSnippet().getDescription()); 
    out.println("Thumbnail: " + thumbnail.getUrl()); 

One possible output follows where parts of the output have been modified:

Kind: null
Video Id: tntO...
Title: Funny Cats ...
Description: Check out the ...
Thumbnail: https://i.ytimg.com/vi/tntO.../default.jpg

We have skipped many error checking steps to simplify the example, but these should be considered when implementing this in a business application.

If we need to download the video, one of the simplest ways is to use axet/wget found at https://github.com/axet/wget. It provides an easy-to-use technique to download the video using its video ID.

In the following example, a URL is created using the video ID. You will need to provide a video ID for this to work properly. The file is saved to the current directory with the video's title as the filename:

    String url = "http://www.youtube.com/watch?v=videoID"; 
    String path = "."; 
    VGet vget = new VGet(new URL(url), new File(path)); 
    vget.download(); 

There are other more sophisticated download techniques found at the GitHub site.