在 android webview 中全屏播放 HTML5视频

嗯,我已经搜索了几天,如何显示全屏模式的 HTML5视频在安卓 WebView。

我设法在我的网络视图上播放 HTML5视频。在全屏模式下显示视频时出现了问题。

据我所知,android 有两种处理 < video > 标签的方式:

  1. 在 android 版本 < = 2.3.3 上,onShowCustomView 方法被触发,我可以拥有 VideoView 实例,并在视频完成时设置监听器,设置控制器等。目前为止还不错。

  2. 在 ICS (可能是3.0及以上版本) 上,< video > 看起来是以不同的方式处理的。当播放 HTML5视频时,onShowCustomView 并没有在正常模式下被调用——看起来 WebView 内部有一个内部业务在播放视频,所有在 < video > 标签中定义的控件都显示出来了——我无法以任何方式访问它。实际上,如果视频是在正常模式下播放,这是可以的,因为控制器在那里并且正在工作。

这就引出了一个大问题: 当以全屏模式显示视频时,会调用 onShowCustomView ——但是在 ICS 上,“ view”参数不是 VideoView 的实例。

我发现这个实例是 VideoSurfaceView,一个 HTML5VideoFullScreen 类的私有内部类。我们能够访问这个内部类的唯一方法是通过反射。

在查看了这个类的 GrepCode 之后,我了解到,与 VideoView 不同,HTML5VideoFullScreen $VideoSurfaceView 没有一个 MediaPlayer 实例,我可以听到它的事件或访问它的控件。我唯一能做的就是把这个 VideoSurfaceView 原封不动地放在一个全屏布局里,而不用控制它。

底线-当全屏显示视频时,我不知道视频什么时候结束,它的控制没有显示-这是相当悲哀的。我拿不到关闭全屏幕的触发器。

我尝试了一些不成功的变通方法:

  1. 反射: 我试图从内部类 VideoSurfaceView 访问持有 MediaPlayer 成员的 HTML5VideoFullScreen 实例。我没有设法得到它,我不确定这是可能的(ViewSurfaceView 不持有其所有者的实例)。

  2. 通过 Javascript 注册视频事件(例如 onend) ,然后通过 JavascriptInterface 在 JAVA 中处理我需要的内容: 我发现这个解决方案不可靠,因为在这样做的时候我遇到了另一个问题: < video > 标签可以嵌套在。Iframe 源代码不是我的,我不能得到它的内容(getElementById 或 getElementsByTagName [ i ]是空值)-这意味着,我不能到达 iframe 中的 < video > 元素。

我仍在寻找解决方案,关于这个问题的文章很少。有人破解了吗?非常感谢您的帮助!

VideoView class: 给你(has MediaPlayer)

HTML5VideoFullScreen $VideoSurfaceView class: 给你(没有 MediaPlayer)

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Edit 2014/10: by popular demand I'm maintaining and moving this to GitHub. Please check cprcrack/VideoEnabledWebView for the last version. Will keep this answer only for reference.

Edit 2014/01: improved example usage to include the nonVideoLayout, videoLayout, and videoLoading views, for those users requesting more example code for better understading.

Edit 2013/12: some bug fixes related to Sony Xperia devices compatibility, but which in fact affected all devices.

Edit 2013/11: after the release of Android 4.4 KitKat (API level 19) with its new Chromium webview, I had to work hard again. Several improvements were made. You should update to this new version. I release this source under WTFPL.

Edit 2013/04: after 1 week of hard work, I finally have achieved everything I needed. I think this two generic classes that I have created can solve all you problems.

VideoEnabledWebChromeClient can be used alone if you do not require the functionality that VideoEnabledWebView adds. But VideoEnabledWebView must always rely on a VideoEnabledWebChromeClient. Please read all the comments of the both classes carefully.

VideoEnabledWebChromeClient class

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's 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's layout that contains every other view that should be hidden when the video goes full-screen.
* @param activityVideoView A ViewGroup in the activity's 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's layout that contains every other view that should be hidden when the video goes full-screen.
* @param activityVideoView A ViewGroup in the activity's 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's layout that contains every other view that should be hidden when the video goes full-screen.
* @param activityVideoView A ViewGroup in the activity's 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's 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's 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;
}
}


}

VideoEnabledWebView class

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;
}
}


}

Example usage:

Main layout activity_main.xml in which we put a VideoEnabledWebView and other used views:

<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>

Activity's onCreate(), in which we initialize it:

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's mobile site
webView.loadUrl("http://m.youtube.com");
}

And don't forget to call 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();
}
}
}

Edit: please see my other answer, as you probably don't need this now.

As you said, in API levels 11+ a HTML5VideoFullScreen$VideoSurfaceView is passed. But I don't think you are right when you say that "it doens't have a MediaPlayer".

This is the way to reach the MediaPlayer instance from the HTML5VideoFullScreen$VideoSurfaceView instance using reflection:

@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.

So, now you could set the onCompletion listener of the MediaPlayer instance like this:

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);

The code doesn't fail but I'm not completely sure if that onCompletion listener will really be called or if it could be useful to your situation. But just in case someone would like to try it.

Thank you so much for that class, Cristian.

I made a minor tweak to it so that the custom loading view is optional, like so:

  @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;
}
}

I also added a new constructor that just takes two parameters. Anyway, just a minor simplification if you don't need the loading view. Thanks again for providing this.

This is great. But if you want your website links to open in the app itself, add this code in your 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;
}
});

Just set
mWebView.setWebChromeClient(new WebChromeClient());

and video plays as normally wont need any custom view.

Cprcrack's answer works very well for API levels 19 and under. Just a minor addition to cprcrack's onShowCustomView will get it working on API level 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);
}

You will also need to reflect the changes in onHideCustomView

It seems that in lollipop and up (or maybe just a different WebView Version) that calling cprcrack's onHideCustomView() method does not work. It works if it is called from the exit fullscreen button but when you specifically call the method it will only exit fullscreen but the webView stays blank. A way around it is to simply add these lines of code to onHideCustomView():

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

This will notify the webView that fullscreen has exited.

Tested on Android 9.0 version

None of the answers worked for me . This is the final thing worked

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);
}
}

In AndroidManifest.xml

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

Source Monster Techno