Ответ 1

Редактировать 2014/10: по многочисленным просьбам я поддерживаю и переношу это на GitHub. Пожалуйста, проверьте cprcrack/VideoEnabledWebView для последней версии. Сохраню этот ответ только для справки.

Изменить 2014/01: улучшенное использование примера, включающее представления nonVideoLayout, videoLayout и videoLoading для тех пользователей, которые запрашивают больше примера кода для лучшего понимания.

Edit 2013/12: исправлены некоторые ошибки, связанные с совместимостью устройств Sony Xperia, но которые фактически затронули все устройства.

Редактировать 2013/11: после выпуска Android 4.4 KitKat (уровень API 19) с его новым веб-представлением Chromium мне снова пришлось много работать. Было сделано несколько улучшений. Вы должны обновить до этой новой версии. Я выпускаю этот источник под WTFPL.

Edit 2013/04: после 1 недели напряженной работы я наконец-то достиг всего, что мне было нужно. Я думаю, что эти два общих класса, которые я создал, могут решить все ваши проблемы.

VideoEnabledWebChromeClient можно использовать отдельно, если вам не требуется функциональность, VideoEnabledWebView добавляет VideoEnabledWebView. Но VideoEnabledWebView всегда должен полагаться на VideoEnabledWebChromeClient. Пожалуйста, внимательно прочитайте все комментарии обоих классов.

Класс VideoEnabledWebChromeClient

import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.media.MediaPlayer.OnErrorListener;
import android.media.MediaPlayer.OnPreparedListener;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.webkit.WebChromeClient;
import android.widget.FrameLayout;

/**
 * This class serves as a WebChromeClient to be set to a WebView, allowing it to play video.
 * Video will play differently depending on target API level (in-line, fullscreen, or both).
 *
 * It has been tested with the following video classes:
 * - android.widget.VideoView (typically API level <11)
 * - android.webkit.HTML5VideoFullScreen$VideoSurfaceView/VideoTextureView (typically API level 11-18)
 * - com.android.org.chromium.content.browser.ContentVideoView$VideoSurfaceView (typically API level 19+)
 * 
 * Important notes:
 * - For API level 11+, android:hardwareAccelerated="true" must be set in the application manifest.
 * - The invoking activity must call VideoEnabledWebChromeClient onBackPressed() inside of its own onBackPressed().
 * - Tested in Android API levels 8-19. Only tested on http://m.youtube.com.
 *
 * @author Cristian Perez (http://cpr.name)
 *
 */
public class VideoEnabledWebChromeClient extends WebChromeClient implements OnPreparedListener, OnCompletionListener, OnErrorListener
{
    public interface ToggledFullscreenCallback
    {
        public void toggledFullscreen(boolean fullscreen);
    }

    private View activityNonVideoView;
    private ViewGroup activityVideoView;
    private View loadingView;
    private VideoEnabledWebView webView;

    private boolean isVideoFullscreen; // Indicates if the video is being displayed using a custom view (typically full-screen)
    private FrameLayout videoViewContainer;
    private CustomViewCallback videoViewCallback;

    private ToggledFullscreenCallback toggledFullscreenCallback;

    /**
     * Never use this constructor alone.
     * This constructor allows this class to be defined as an inline inner class in which the user can override methods
     */
    @SuppressWarnings("unused")
    public VideoEnabledWebChromeClient()
    {
    }

    /**
     * Builds a video enabled WebChromeClient.
     * @param activityNonVideoView A View in the activity layout that contains every other view that should be hidden when the video goes full-screen.
     * @param activityVideoView A ViewGroup in the activity layout that will display the video. Typically you would like this to fill the whole layout.
     */
    @SuppressWarnings("unused")
    public VideoEnabledWebChromeClient(View activityNonVideoView, ViewGroup activityVideoView)
    {
        this.activityNonVideoView = activityNonVideoView;
        this.activityVideoView = activityVideoView;
        this.loadingView = null;
        this.webView = null;
        this.isVideoFullscreen = false;
    }

    /**
     * Builds a video enabled WebChromeClient.
     * @param activityNonVideoView A View in the activity layout that contains every other view that should be hidden when the video goes full-screen.
     * @param activityVideoView A ViewGroup in the activity layout that will display the video. Typically you would like this to fill the whole layout.
     * @param loadingView A View to be shown while the video is loading (typically only used in API level <11). Must be already inflated and without a parent view.
     */
    @SuppressWarnings("unused")
    public VideoEnabledWebChromeClient(View activityNonVideoView, ViewGroup activityVideoView, View loadingView)
    {
        this.activityNonVideoView = activityNonVideoView;
        this.activityVideoView = activityVideoView;
        this.loadingView = loadingView;
        this.webView = null;
        this.isVideoFullscreen = false;
    }

    /**
     * Builds a video enabled WebChromeClient.
     * @param activityNonVideoView A View in the activity layout that contains every other view that should be hidden when the video goes full-screen.
     * @param activityVideoView A ViewGroup in the activity layout that will display the video. Typically you would like this to fill the whole layout.
     * @param loadingView A View to be shown while the video is loading (typically only used in API level <11). Must be already inflated and without a parent view.
     * @param webView The owner VideoEnabledWebView. Passing it will enable the VideoEnabledWebChromeClient to detect the HTML5 video ended event and exit full-screen.
     * Note: The web page must only contain one video tag in order for the HTML5 video ended event to work. This could be improved if needed (see Javascript code).
     */
    public VideoEnabledWebChromeClient(View activityNonVideoView, ViewGroup activityVideoView, View loadingView, VideoEnabledWebView webView)
    {
        this.activityNonVideoView = activityNonVideoView;
        this.activityVideoView = activityVideoView;
        this.loadingView = loadingView;
        this.webView = webView;
        this.isVideoFullscreen = false;
    }

    /**
     * Indicates if the video is being displayed using a custom view (typically full-screen)
     * @return true it the video is being displayed using a custom view (typically full-screen)
     */
    public boolean isVideoFullscreen()
    {
        return isVideoFullscreen;
    }

    /**
     * Set a callback that will be fired when the video starts or finishes displaying using a custom view (typically full-screen)
     * @param callback A VideoEnabledWebChromeClient.ToggledFullscreenCallback callback
     */
    public void setOnToggledFullscreen(ToggledFullscreenCallback callback)
    {
        this.toggledFullscreenCallback = callback;
    }

    @Override
    public void onShowCustomView(View view, CustomViewCallback callback)
    {
        if (view instanceof FrameLayout)
        {
            // A video wants to be shown
            FrameLayout frameLayout = (FrameLayout) view;
            View focusedChild = frameLayout.getFocusedChild();

            // Save video related variables
            this.isVideoFullscreen = true;
            this.videoViewContainer = frameLayout;
            this.videoViewCallback = callback;

            // Hide the non-video view, add the video view, and show it
            activityNonVideoView.setVisibility(View.INVISIBLE);
            activityVideoView.addView(videoViewContainer, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
            activityVideoView.setVisibility(View.VISIBLE);

            if (focusedChild instanceof android.widget.VideoView)
            {
                // android.widget.VideoView (typically API level <11)
                android.widget.VideoView videoView = (android.widget.VideoView) focusedChild;

                // Handle all the required events
                videoView.setOnPreparedListener(this);
                videoView.setOnCompletionListener(this);
                videoView.setOnErrorListener(this);
            }
            else
            {
                // Other classes, including:
                // - android.webkit.HTML5VideoFullScreen$VideoSurfaceView, which inherits from android.view.SurfaceView (typically API level 11-18)
                // - android.webkit.HTML5VideoFullScreen$VideoTextureView, which inherits from android.view.TextureView (typically API level 11-18)
                // - com.android.org.chromium.content.browser.ContentVideoView$VideoSurfaceView, which inherits from android.view.SurfaceView (typically API level 19+)

                // Handle HTML5 video ended event only if the class is a SurfaceView
                // Test case: TextureView of Sony Xperia T API level 16 doesn't work fullscreen when loading the javascript below
                if (webView != null && webView.getSettings().getJavaScriptEnabled() && focusedChild instanceof SurfaceView)
                {
                    // Run javascript code that detects the video end and notifies the Javascript interface
                    String js = "javascript:";
                    js += "var _ytrp_html5_video_last;";
                    js += "var _ytrp_html5_video = document.getElementsByTagName('video')[0];";
                    js += "if (_ytrp_html5_video != undefined && _ytrp_html5_video != _ytrp_html5_video_last) {";
                    {
                        js += "_ytrp_html5_video_last = _ytrp_html5_video;";
                        js += "function _ytrp_html5_video_ended() {";
                        {
                            js += "_VideoEnabledWebView.notifyVideoEnd();"; // Must match Javascript interface name and method of VideoEnableWebView
                        }
                        js += "}";
                        js += "_ytrp_html5_video.addEventListener('ended', _ytrp_html5_video_ended);";
                    }
                    js += "}";
                    webView.loadUrl(js);
                }
            }

            // Notify full-screen change
            if (toggledFullscreenCallback != null)
            {
                toggledFullscreenCallback.toggledFullscreen(true);
            }
        }
    }

    @Override @SuppressWarnings("deprecation")
    public void onShowCustomView(View view, int requestedOrientation, CustomViewCallback callback) // Available in API level 14+, deprecated in API level 18+
    {
        onShowCustomView(view, callback);
    }

    @Override
    public void onHideCustomView()
    {
        // This method should be manually called on video end in all cases because it not always called automatically.
        // This method must be manually called on back key press (from this class' onBackPressed() method).

        if (isVideoFullscreen)
        {
            // Hide the video view, remove it, and show the non-video view
            activityVideoView.setVisibility(View.INVISIBLE);
            activityVideoView.removeView(videoViewContainer);
            activityNonVideoView.setVisibility(View.VISIBLE);

            // Call back (only in API level <19, because in API level 19+ with chromium webview it crashes)
            if (videoViewCallback != null && !videoViewCallback.getClass().getName().contains(".chromium."))
            {
                videoViewCallback.onCustomViewHidden();
            }

            // Reset video related variables
            isVideoFullscreen = false;
            videoViewContainer = null;
            videoViewCallback = null;

            // Notify full-screen change
            if (toggledFullscreenCallback != null)
            {
                toggledFullscreenCallback.toggledFullscreen(false);
            }
        }
    }

    @Override
    public View getVideoLoadingProgressView() // Video will start loading
    {
        if (loadingView != null)
        {
            loadingView.setVisibility(View.VISIBLE);
            return loadingView;
        }
        else
        {
            return super.getVideoLoadingProgressView();
        }
    }

    @Override
    public void onPrepared(MediaPlayer mp) // Video will start playing, only called in the case of android.widget.VideoView (typically API level <11)
    {
        if (loadingView != null)
        {
            loadingView.setVisibility(View.GONE);
        }
    }

    @Override
    public void onCompletion(MediaPlayer mp) // Video finished playing, only called in the case of android.widget.VideoView (typically API level <11)
    {
        onHideCustomView();
    }

    @Override
    public boolean onError(MediaPlayer mp, int what, int extra) // Error while playing video, only called in the case of android.widget.VideoView (typically API level <11)
    {
        return false; // By returning false, onCompletion() will be called
    }

    /**
     * Notifies the class that the back key has been pressed by the user.
     * This must be called from the Activity onBackPressed(), and if it returns false, the activity itself should handle it. Otherwise don't do anything.
     * @return Returns true if the event was handled, and false if was not (video view is not visible)
     */
    public boolean onBackPressed()
    {
        if (isVideoFullscreen)
        {
            onHideCustomView();
            return true;
        }
        else
        {
            return false;
        }
    }

}

Класс VideoEnabledWebView

import android.annotation.SuppressLint;
import android.content.Context;
import android.os.Handler;
import android.os.Looper;
import android.util.AttributeSet;
import android.webkit.WebChromeClient;
import android.webkit.WebView;

import java.util.Map;

/**
 * This class serves as a WebView to be used in conjunction with a VideoEnabledWebChromeClient.
 * It makes possible:
 * - To detect the HTML5 video ended event so that the VideoEnabledWebChromeClient can exit full-screen.
 * 
 * Important notes:
 * - Javascript is enabled by default and must not be disabled with getSettings().setJavaScriptEnabled(false).
 * - setWebChromeClient() must be called before any loadData(), loadDataWithBaseURL() or loadUrl() method.
 *
 * @author Cristian Perez (http://cpr.name)
 *
 */
public class VideoEnabledWebView extends WebView
{
    public class JavascriptInterface
    {
        @android.webkit.JavascriptInterface
        public void notifyVideoEnd() // Must match Javascript interface method of VideoEnabledWebChromeClient
        {
            // This code is not executed in the UI thread, so we must force that to happen
            new Handler(Looper.getMainLooper()).post(new Runnable()
            {
                @Override
                public void run()
                {
                    if (videoEnabledWebChromeClient != null)
                    {
                        videoEnabledWebChromeClient.onHideCustomView();
                    }
                }
            });
        }
    }

    private VideoEnabledWebChromeClient videoEnabledWebChromeClient;
    private boolean addedJavascriptInterface;

    public VideoEnabledWebView(Context context)
    {
        super(context);
        addedJavascriptInterface = false;
    }

    @SuppressWarnings("unused")
    public VideoEnabledWebView(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        addedJavascriptInterface = false;
    }

    @SuppressWarnings("unused")
    public VideoEnabledWebView(Context context, AttributeSet attrs, int defStyle)
    {
        super(context, attrs, defStyle);
        addedJavascriptInterface = false;
    }

    /**
     * Indicates if the video is being displayed using a custom view (typically full-screen)
     * @return true it the video is being displayed using a custom view (typically full-screen)
     */
    public boolean isVideoFullscreen()
    {
        return videoEnabledWebChromeClient != null && videoEnabledWebChromeClient.isVideoFullscreen();
    }

    /**
     * Pass only a VideoEnabledWebChromeClient instance.
     */
    @Override @SuppressLint("SetJavaScriptEnabled")
    public void setWebChromeClient(WebChromeClient client)
    {
        getSettings().setJavaScriptEnabled(true);

        if (client instanceof VideoEnabledWebChromeClient)
        {
            this.videoEnabledWebChromeClient = (VideoEnabledWebChromeClient) client;
        }

        super.setWebChromeClient(client);
    }

    @Override
    public void loadData(String data, String mimeType, String encoding)
    {
        addJavascriptInterface();
        super.loadData(data, mimeType, encoding);
    }

    @Override
    public void loadDataWithBaseURL(String baseUrl, String data, String mimeType, String encoding, String historyUrl)
    {
        addJavascriptInterface();
        super.loadDataWithBaseURL(baseUrl, data, mimeType, encoding, historyUrl);
    }

    @Override
    public void loadUrl(String url)
    {
        addJavascriptInterface();
        super.loadUrl(url);
    }

    @Override
    public void loadUrl(String url, Map<String, String> additionalHttpHeaders)
    {
        addJavascriptInterface();
        super.loadUrl(url, additionalHttpHeaders);
    }

    private void addJavascriptInterface()
    {
        if (!addedJavascriptInterface)
        {
            // Add javascript interface to be called when the video ends (must be done before page load)
            addJavascriptInterface(new JavascriptInterface(), "_VideoEnabledWebView"); // Must match Javascript interface name of VideoEnabledWebChromeClient

            addedJavascriptInterface = true;
        }
    }

}

Пример использования:

Основной макет activity_main.xml, в который мы помещаем VideoEnabledWebView и другие используемые представления:

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <!-- View that will be hidden when video goes fullscreen -->
    <RelativeLayout
        android:id="@+id/nonVideoLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

        <your.package.VideoEnabledWebView
            android:id="@+id/webView"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

    </RelativeLayout>   

    <!-- View where the video will be shown when video goes fullscreen -->
    <RelativeLayout
        android:id="@+id/videoLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >

        <!-- View that will be shown while the fullscreen video loads (maybe include a spinner and a "Loading..." message) -->
        <View
            android:id="@+id/videoLoading"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            android:visibility="invisible" />

    </RelativeLayout>

</RelativeLayout>

Действие onCreate(), в котором мы его инициализируем:

private VideoEnabledWebView webView;
private VideoEnabledWebChromeClient webChromeClient;

@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);

    // Set layout
    setContentView(R.layout.activity_main);

    // Save the web view
    webView = (VideoEnabledWebView) findViewById(R.id.webView);

    // Initialize the VideoEnabledWebChromeClient and set event handlers
    View nonVideoLayout = findViewById(R.id.nonVideoLayout); // Your own view, read class comments
    ViewGroup videoLayout = (ViewGroup) findViewById(R.id.videoLayout); // Your own view, read class comments
    View loadingView = getLayoutInflater().inflate(R.layout.view_loading_video, null); // Your own view, read class comments
    webChromeClient = new VideoEnabledWebChromeClient(nonVideoLayout, videoLayout, loadingView, webView) // See all available constructors...
    {
        // Subscribe to standard events, such as onProgressChanged()...
        @Override
        public void onProgressChanged(WebView view, int progress)
        {
            // Your code...
        }
    };
    webChromeClient.setOnToggledFullscreen(new VideoEnabledWebChromeClient.ToggledFullscreenCallback()
    {
        @Override
        public void toggledFullscreen(boolean fullscreen)
        {
            // Your code to handle the full-screen change, for example showing and hiding the title bar. Example:
            if (fullscreen)
            {
                WindowManager.LayoutParams attrs = getWindow().getAttributes();
                attrs.flags |= WindowManager.LayoutParams.FLAG_FULLSCREEN;
                attrs.flags |= WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
                getWindow().setAttributes(attrs);
                if (android.os.Build.VERSION.SDK_INT >= 14)
                {
                    getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LOW_PROFILE);
                }
            }
            else
            {
                WindowManager.LayoutParams attrs = getWindow().getAttributes();
                attrs.flags &= ~WindowManager.LayoutParams.FLAG_FULLSCREEN;
                attrs.flags &= ~WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON;
                getWindow().setAttributes(attrs);
                if (android.os.Build.VERSION.SDK_INT >= 14)
                {
                    getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_VISIBLE);
                }
            }

        }
    });
    webView.setWebChromeClient(webChromeClient);

    // Navigate everywhere you want, this classes have only been tested on YouTube mobile site
    webView.loadUrl("http://m.youtube.com");
}

И не забудьте вызвать onBackPressed():

@Override
public void onBackPressed()
{
    // Notify the VideoEnabledWebChromeClient, and handle it ourselves if it doesn't handle it
    if (!webChromeClient.onBackPressed())
    {
        if (webView.canGoBack())
        {
            webView.goBack();
        }
        else
        {
            // Close app (presumably)
            super.onBackPressed();
        }
    }
}

Ответ 2

Изменить: см. мой другой ответ, поскольку вам, вероятно, сейчас это не нужно.

Как вы сказали, в уровнях API 11+ передается HTML5VideoFullScreen $VideoSurfaceView. Но я не думаю, что вы правы, когда говорите, что "у него нет MediaPlayer".

Это способ получить экземпляр MediaPlayer из экземпляра HTML5VideoFullScreen $VideoSurfaceView, используя отражение:

@SuppressWarnings("rawtypes")
Class c1 = Class.forName("android.webkit.HTML5VideoFullScreen$VideoSurfaceView");
Field f1 = c1.getDeclaredField("this$0");
f1.setAccessible(true);

@SuppressWarnings("rawtypes")
Class c2 = f1.getType().getSuperclass();
Field f2 = c2.getDeclaredField("mPlayer");
f2.setAccessible(true);

Object ___html5VideoViewInstance = f1.get(focusedChild); // Look at the code in my other answer to this same question to see whats focusedChild

Object ___mpInstance = f2.get(___html5VideoViewInstance); // This is the MediaPlayer instance.

Итак, теперь вы можете установить прослушиватель onCompletion экземпляра MediaPlayer следующим образом:

OnCompletionListener ocl = new OnCompletionListener()
{
    @Override
    public void onCompletion(MediaPlayer mp)
    {
        // Do stuff
    }
};

Method m1 = f2.getType().getMethod("setOnCompletionListener", new Class[] { Class.forName("android.media.MediaPlayer$OnCompletionListener") });
m1.invoke(___mpInstance, ocl);

Код не работает, но я не совсем уверен, действительно ли этот прослушиватель onCompletion будет действительно вызван или может быть полезен для вашей ситуации. Но на всякий случай кто-то хотел бы попробовать.

Ответ 3

Просто установите   mWebView.setWebChromeClient(new WebChromeClient());

а видео воспроизводится так, как обычно, не требуется никакого пользовательского вида.

Ответ 4

Большое вам спасибо за этот класс, Кристиан.

Я сделал небольшую настройку, чтобы пользовательское загрузочное представление было необязательным, например:

  @Override
    public View getVideoLoadingProgressView() // Video will start loading, only called in the case of VideoView (typically API level 10-)
    {
        if (loadingView == null)
        {
            return super.getVideoLoadingProgressView();
        }
        else
        {
            loadingView.setVisibility(View.VISIBLE);
            return loadingView;
        }
    }

Я также добавил новый конструктор, который просто принимает два параметра. Во всяком случае, просто небольшое упрощение, если вам не нужен вид загрузки. Еще раз спасибо за предоставление этого.

Ответ 5

Это здорово. Но если вы хотите, чтобы ваши ссылки на сайт открывались в самом приложении, добавьте этот код в свой пример ExampleActivity.java:

webView.setWebViewClient(new WebViewClient() {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            if (Uri.parse(url).getHost().endsWith("yourwebsite.com")) {
                return false;
            }

            Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
            view.getContext().startActivity(intent);
            return true;
        }
    });

Ответ 6

Ответ Cprcrack очень хорошо работает для уровней API 19 и ниже. Просто небольшое дополнение к cprcrack onShowCustomView позволит ему работать на уровне API 21 +

if (Build.VERSION.SDK_INT >= 21) {
      videoViewContainer.setBackgroundColor(Color.BLACK);
      ((ViewGroup) webView.getParent()).addView(videoViewContainer);
      webView.scrollTo(0,0);  // centers full screen view 
} else {
      activityNonVideoView.setVisibility(View.INVISIBLE);
      ViewGroup.LayoutParams vg = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                    ViewGroup.LayoutParams.MATCH_PARENT);
      activityVideoView.addView(videoViewContainer,vg);
      activityVideoView.setVisibility(View.VISIBLE);
}

Вам также необходимо будет отразить изменения в onHideCustomView

Ответ 7

Кажется, что в lollipop и up (или, может быть, только в другой версии WebView) метод вызова cprcrack's onHideCustomView() не работает. Он работает, если он вызывается из полноэкранной кнопки выхода, но когда вы специально вызываете метод, он выйдет из полноэкранного режима, но webView останется пустым. Кстати, это просто добавить эти строки кода в onHideCustomView():

String js = "javascript:";
js += "var _ytrp_html5_video = document.getElementsByTagName('video')[0];";
js += "_ytrp_html5_video.webkitExitFullscreen();";
webView.loadUrl(js);

Это уведомит веб-экран о том, что полноэкранный режим вышел.

Ответ 8

Проверено на версии Android 9.0

Ни один из ответов не сработал для меня. Это последнее, что сработало

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.FrameLayout;
import android.widget.ProgressBar;

public class MainActivity extends AppCompatActivity {

    WebView mWebView;


    @SuppressLint("SetJavaScriptEnabled")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        mWebView = (WebView) findViewById(R.id.webView);


        mWebView.setWebViewClient(new WebViewClient());
        mWebView.setWebChromeClient(new MyChrome());
        WebSettings webSettings = mWebView.getSettings();
        webSettings.setJavaScriptEnabled(true);
        webSettings.setAllowFileAccess(true);
        webSettings.setAppCacheEnabled(true);

       if (savedInstanceState == null) {
          mWebView.loadUrl("https://www.youtube.com/");
       }

    }


    private class MyChrome extends WebChromeClient {

        private View mCustomView;
        private WebChromeClient.CustomViewCallback mCustomViewCallback;
        protected FrameLayout mFullscreenContainer;
        private int mOriginalOrientation;
        private int mOriginalSystemUiVisibility;

        MyChrome() {}

        public Bitmap getDefaultVideoPoster()
        {
            if (mCustomView == null) {
                return null;
            }
            return BitmapFactory.decodeResource(getApplicationContext().getResources(), 2130837573);
        }

        public void onHideCustomView()
        {
            ((FrameLayout)getWindow().getDecorView()).removeView(this.mCustomView);
            this.mCustomView = null;
            getWindow().getDecorView().setSystemUiVisibility(this.mOriginalSystemUiVisibility);
            setRequestedOrientation(this.mOriginalOrientation);
            this.mCustomViewCallback.onCustomViewHidden();
            this.mCustomViewCallback = null;
        }

        public void onShowCustomView(View paramView, WebChromeClient.CustomViewCallback paramCustomViewCallback)
        {
            if (this.mCustomView != null)
            {
                onHideCustomView();
                return;
            }
            this.mCustomView = paramView;
            this.mOriginalSystemUiVisibility = getWindow().getDecorView().getSystemUiVisibility();
            this.mOriginalOrientation = getRequestedOrientation();
            this.mCustomViewCallback = paramCustomViewCallback;
            ((FrameLayout)getWindow().getDecorView()).addView(this.mCustomView, new FrameLayout.LayoutParams(-1, -1));
            getWindow().getDecorView().setSystemUiVisibility(3846 | View.SYSTEM_UI_FLAG_LAYOUT_STABLE);
        }
    }

 @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        mWebView.saveState(outState);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        mWebView.restoreState(savedInstanceState);
    }
}

В AndroidManifest.xml

<activity
  android:name=".MainActivity"
  android:configChanges="orientation|screenSize" />

Источник Монстр Техно