Youtube AS3 API简单问题

Question

我正在尝试在我的 Flash 网站中添加 YouTube 播放器。我从 youtube api 网站下载了 AS3Player 类文件并将其链接到我的 flash 文件中。当我运行它时，我收到编译器错误，显示 C:/project/flash/youtube/player/AS3Player.as : TheDefinition of the base class Canvas was not found

和

C:/project/flash/youtube/player/AS3Player.as :
The class youtube/player/AS3Player must subclass of "flash.display.MovieClip" since it is linked to the library symbol of that type.

我的 AS3Player.as

package youtube.player {
  import flash.events.Event;
  import flash.events.IOErrorEvent;
  import flash.events.MouseEvent;
  import flash.net.URLLoader;
  import flash.net.URLRequest;
  import flash.net.URLVariables;
  import flash.system.Security;
  import mx.containers.Canvas;
  import mx.controls.Button;
  import mx.controls.ComboBox;
  import mx.controls.SWFLoader;
  import mx.controls.TextInput;
  import mx.events.ListEvent;


  public class AS3Player extends Canvas {
    // Member variables.
    private var cueButton:Button;
    private var isQualityPopulated:Boolean;
    private var isWidescreen:Boolean;
    private var pauseButton:Button;
    private var playButton:Button;
    private var player:Object;
    private var playerLoader:SWFLoader;
    private var qualityComboBox:ComboBox;
    private var videoIdTextInput:TextInput;
    private var youtubeApiLoader:URLLoader;

    // CONSTANTS.
    private static const DEFAULT_VIDEO_ID:String = "0QRO3gKj3qw";
    private static const PLAYER_URL:String =
        "http://www.youtube.com/apiplayer?version=3";
    private static const SECURITY_DOMAIN:String = "http://www.youtube.com";
    private static const YOUTUBE_API_PREFIX:String =
        "http://gdata.youtube.com/feeds/api/videos/";
    private static const YOUTUBE_API_VERSION:String = "2";
    private static const YOUTUBE_API_FORMAT:String = "5";
    private static const WIDESCREEN_ASPECT_RATIO:String = "widescreen";
    private static const QUALITY_TO_PLAYER_WIDTH:Object = {
      small: 320,
      medium: 640,
      large: 854,
      hd720: 1280
    };
    private static const STATE_ENDED:Number = 0;
    private static const STATE_PLAYING:Number = 1;
    private static const STATE_PAUSED:Number = 2;
    private static const STATE_CUED:Number = 5;

    public function AS3Player():void {
      // Specifically allow the chromless player .swf access to our .swf.
      Security.allowDomain(SECURITY_DOMAIN);

      setupUi();
      setupPlayerLoader();
      setupYouTubeApiLoader();
    }

    private function setupUi():void {
      // Create a TextInput field for the YouTube video id, and pre-populate it.
      videoIdTextInput = new TextInput();
      videoIdTextInput.text = DEFAULT_VIDEO_ID;
      videoIdTextInput.width = 100;
      videoIdTextInput.x = 10;
      videoIdTextInput.y = 10;
      addChild(videoIdTextInput);

      // Create a Button for cueing up the video whose id is specified.
      cueButton = new Button();
      cueButton.enabled = false;
      cueButton.label = "Cue Video";
      cueButton.width = 100;
      cueButton.x = 120;
      cueButton.y = 10;
      cueButton.addEventListener(MouseEvent.CLICK, cueButtonClickHandler);
      addChild(cueButton);

      // Create a ComboBox that will contain the list of available playback
      // qualities. Selecting from the ComboBox will change the playback quality
      // and resize the player. Note that playback qualities are only available
      // once a video has started playing, so the values in this ComboBox can't
      // be populated until then.
      qualityComboBox = new ComboBox();
      qualityComboBox.prompt = "n/a";
      qualityComboBox.width = 100;
      qualityComboBox.x = 230;
      qualityComboBox.y = 10;
      qualityComboBox.addEventListener(ListEvent.CHANGE,
                                       qualityComboBoxChangeHandler);
      addChild(qualityComboBox);

      // Create a Button for playing the cued video.
      playButton = new Button();
      playButton.enabled = false;
      playButton.label = "Play";
      playButton.width = 100;
      playButton.x = 340;
      playButton.y = 10;
      playButton.addEventListener(MouseEvent.CLICK, playButtonClickHandler);
      addChild(playButton);

      // Create a Button for pausing the cued video.
      pauseButton = new Button();
      pauseButton.enabled = false;
      pauseButton.label = "Pause";
      pauseButton.width = 100;
      pauseButton.x = 450;
      pauseButton.y = 10;
      pauseButton.addEventListener(MouseEvent.CLICK, pauseButtonClickHandler);
      addChild(pauseButton);
    }

    private function setupPlayerLoader():void {
      playerLoader = new SWFLoader();
      playerLoader.addEventListener(Event.INIT, playerLoaderInitHandler);
      playerLoader.load(PLAYER_URL);
    }

    private function playerLoaderInitHandler(event:Event):void {
      addChild(playerLoader);
      playerLoader.content.addEventListener("onReady", onPlayerReady);
      playerLoader.content.addEventListener("onError", onPlayerError);
      playerLoader.content.addEventListener("onStateChange",
                                            onPlayerStateChange);
      playerLoader.content.addEventListener("onPlaybackQualityChange",
                                            onVideoPlaybackQualityChange);
    }

    private function setupYouTubeApiLoader():void {
      youtubeApiLoader = new URLLoader();
      youtubeApiLoader.addEventListener(IOErrorEvent.IO_ERROR,
                                        youtubeApiLoaderErrorHandler);
      youtubeApiLoader.addEventListener(Event.COMPLETE,
                                        youtubeApiLoaderCompleteHandler);
    }

    private function youtubeApiLoaderCompleteHandler(event:Event):void {
      var atomData:String = youtubeApiLoader.data;

      // Parse the YouTube API XML response and get the value of the
      // aspectRatio element.
      var atomXml:XML = new XML(atomData);
      var aspectRatios:XMLList = atomXml..*::aspectRatio;

      isWidescreen = aspectRatios.toString() == WIDESCREEN_ASPECT_RATIO;

      isQualityPopulated = false;
      // Cue up the video once we know whether it's widescreen.
      // Alternatively, you could start playing instead of cueing with
      // player.loadVideoById(videoIdTextInput.text);
      player.cueVideoById(videoIdTextInput.text);
    }

    private function qualityComboBoxChangeHandler(event:Event):void {
      var qualityLevel:String = ComboBox(event.target).selectedLabel;
      player.setPlaybackQuality(qualityLevel);
    }

    private function cueButtonClickHandler(event:MouseEvent):void {
      var request:URLRequest = new URLRequest(YOUTUBE_API_PREFIX +
                                              videoIdTextInput.text);

      var urlVariables:URLVariables = new URLVariables();
      urlVariables.v = YOUTUBE_API_VERSION;
      urlVariables.format = YOUTUBE_API_FORMAT;
      request.data = urlVariables;

      try {
        youtubeApiLoader.load(request);
      } catch (error:SecurityError) {
        trace("A SecurityError occurred while loading", request.url);
      }
    }

    private function playButtonClickHandler(event:MouseEvent):void {
      player.playVideo();
    }

    private function pauseButtonClickHandler(event:MouseEvent):void {
      player.pauseVideo();
    }

    private function youtubeApiLoaderErrorHandler(event:IOErrorEvent):void {
      trace("Error making YouTube API request:", event);
    }

    private function onPlayerReady(event:Event):void {
      player = playerLoader.content;
      player.visible = false;

      cueButton.enabled = true;
    }

    private function onPlayerError(event:Event):void {
      trace("Player error:", Object(event).data);
    }

    private function onPlayerStateChange(event:Event):void {
      trace("State is", Object(event).data);

      switch (Object(event).data) {
        case STATE_ENDED:
          playButton.enabled = true;
          pauseButton.enabled = false;
          break;

        case STATE_PLAYING:
          playButton.enabled = false;
          pauseButton.enabled = true;

          if(!isQualityPopulated) {
            populateQualityComboBox();
          }
          break;

        case STATE_PAUSED:
          playButton.enabled = true;
          pauseButton.enabled = false;
          break;

        case STATE_CUED:
          playButton.enabled = true;
          pauseButton.enabled = false;

          resizePlayer("medium");
          break;
      }
    }

    private function onVideoPlaybackQualityChange(event:Event):void {
      trace("Current video quality:", Object(event).data);
      resizePlayer(Object(event).data);
    }

    private function resizePlayer(qualityLevel:String):void {
      var newWidth:Number = QUALITY_TO_PLAYER_WIDTH[qualityLevel] || 640;
      var newHeight:Number;

      if (isWidescreen) {
        // Widescreen videos (usually) fit into a 16:9 player.
        newHeight = newWidth * 9 / 16;
      } else {
        // Non-widescreen videos fit into a 4:3 player.
        newHeight = newWidth * 3 / 4;
      }

      trace("isWidescreen is", isWidescreen, ". Size:", newWidth, newHeight);
      player.setSize(newWidth, newHeight);

      // Center the resized player on the stage.
      player.x = (stage.stageWidth - newWidth) / 2;
      player.y = (stage.stageHeight - newHeight) / 2;

      player.visible = true;
    }

    private function populateQualityComboBox():void {
      isQualityPopulated = true;

      var qualities:Array = player.getAvailableQualityLevels();
      qualityComboBox.dataProvider = qualities;

      var currentQuality:String = player.getPlaybackQuality();
      qualityComboBox.selectedItem = currentQuality;
    }
  }
}

我真的需要把它拿下来。如果有人能帮助我，我很感激。谢谢。

Answer 1

Canvas 类是 Flex 框架的一部分，因此代码中的第一个错误可能如下：

import mx.containers.Canvas;

应用程序找不到 mx.containers 包。

如果您不使用 Flex ，那么您将需要找到不使用 Flex 类的另一个版本的播放器。

看看这里：
http://code.google.com/apis/youtube/articles/tubeloc。 html

虽然可能还有其他例子......