1、原理

利用 WebChromeClient 中的 onShowCustomView 和 onHideCustomView 方法来实现全屏功能

2、创建一个activity_web_view.xml 文件 里面放一个WebView 和 Fragment

<?xml version="1.0" encoding="UTF-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    tools:context=".ui.activity.WebViewActivity" 
    android:layout_height="match_parent" 
    android:layout_width="match_parent" 
    xmlns:tools="http://schemas.android.com/tools" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    xmlns:android="http://schemas.android.com/apk/res/android">
 
    <WebView 
        android:layout_height="match_parent"
        android:layout_width="match_parent" 
        app:layout_constraintVertical_bias="0.0" 
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintLeft_toLeftOf="parent" 
        app:layout_constraintHorizontal_bias="0.0"
        android:orientation="vertical" 
        android:id="@+id/view"/>
 
 
    <FrameLayout
        android:id="@+id/frameLayout"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </FrameLayout>
 
</androidx.constraintlayout.widget.ConstraintLayout>

3、创建一个WebViewActivity.java文件，获取WebView和Fragment，并实现WebView相关方法

public class WebViewActivity extends AppCompatActivity{
    private View mCustomView;
    private FrameLayout mFrameLayout;
    private WebChromeClient.CustomViewCallback mCustomViewCallback;
    private WebView mWebView;

     @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_web_view);
        mWebView = findViewById(R.id.view);
        mFrameLayout = findViewById(R.id.frameLayout);
        setWebView();
        //这里使用是腾讯视频的链接
        mWebView.load("https://v.qq.com/x/cover/mzc00200k1qzwd5/k0046p8c271.html");
    }
 
    privte void setWebView(){
        
        WebSettings webSettings = mWebView.getSettings();
        //必须设置否则，无法执行js函数
        webSettings.setJavaScriptEnabled(true);
        mWebView.setWebChromeClient(new WebChromeClient() {
            
            @Override
            public void onShowCustomView(View view, CustomViewCallback callback) {
                super.onShowCustomView(view, callback);
                //点击视频中的全屏按钮，会执行当前方法
                //然后将frameLayout显示隐藏WebView控件便可实现全屏，并横竖屏切换
                if (mCustomView != null) {
                    callback.onCustomViewHidden();
                    return;
                }
                mCustomView = view;
                mFrameLayout.addView(mCustomView);
                mCustomViewCallback = callback;
                setVisibility(View.GONE);      
                //切换横屏            
                setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
            }
 
            @Override
            public void onHideCustomView() {
                setVisibility(View.VISIBLE);
                //当退出全屏时会执行当前方法
                //然后将frameLayout隐藏显示WebView就可以了，记得切换竖屏
                if (mCustomView == null) {
                    return;
                }
                mCustomView.setVisibility(View.GONE);
                mFrameLayout.removeView(mCustomView);
                mCustomViewCallback.onCustomViewHidden();
                mCustomView = null;
                //切换竖屏
                setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
                super.onHideCustomView();
            }
        }
    }
}

4、横竖屏切换时处理状态栏

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {// 横屏
            //状态栏沉浸式样式处理
        } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {// 竖屏
            //状态栏默认样式处理
        }
    }