WebView实现视频全屏播放

WebView可以通过以下步骤实现视频全屏播放：

1. 在WebViewClient中重写shouldOverrideUrlLoading方法，拦截视频链接。

2. 在拦截到视频链接时，创建一个全屏的Activity，并将WebView添加到该Activity中。

3. 隐藏状态栏、导航栏等UI元素，让WebView占据整个屏幕。

4. 在WebView中播放视频。

5. 在Activity销毁时，将WebView从该Activity中移除，并恢复原来的UI状态。

下面是一个示例代码：

public class VideoWebViewClient extends WebViewClient {
    private Activity mActivity;
    private WebView mWebView;
    private View mCustomView;
    private WebChromeClient.CustomViewCallback mCustomViewCallback;

    public VideoWebViewClient(Activity activity, WebView webView) {
        mActivity = activity;
        mWebView = webView;
    }

    @Override
    public boolean shouldOverrideUrlLoading(WebView view, String url) {
        if (url.endsWith(".mp4") || url.endsWith(".avi") || url.endsWith(".3gp") || url.endsWith(".wmv")) {
            Intent intent = new Intent(mActivity, FullScreenVideoActivity.class);
            intent.putExtra("url", url);
            mActivity.startActivity(intent);
            return true;
        }
        return false;
    }

    public void onHideCustomView() {
        if (mCustomView == null) {
            return;
        }
        mCustomView.setVisibility(View.GONE);
        mWebView.setVisibility(View.VISIBLE);
        mCustomViewCallback.onCustomViewHidden();
        mCustomView = null;
        mCustomViewCallback = null;

        // Show the status bar.
        View decorView = mActivity.getWindow().getDecorView();
        decorView.setSystemUiVisibility(View.SYSTEM_UI_FLAG_VISIBLE);
        mActivity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
    }

    public void onShowCustomView(View view, WebChromeClient.CustomViewCallback callback) {
        if (mCustomView != null) {
            onHideCustomView();
            return;
        }
        mCustomView = view;
        mWebView.setVisibility(View.GONE);
        mCustomView.setVisibility(View.VISIBLE);
        mCustomViewCallback = callback;

        // Hide the status bar.
        View decorView = mActivity.getWindow().getDecorView();
        int uiOptions = View.SYSTEM_UI_FLAG_FULLSCREEN;
        decorView.setSystemUiVisibility(uiOptions);
        mActivity.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
    }
}

public class FullScreenVideoActivity extends Activity {
    private WebView mWebView;
    private String mUrl;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_full_screen_video);

        mWebView = findViewById(R.id.webview);
        mUrl = getIntent().getStringExtra("url");

        mWebView.getSettings().setJavaScriptEnabled(true);
        mWebView.setWebViewClient(new VideoWebViewClient(this, mWebView));
        mWebView.setWebChromeClient(new WebChromeClient() {
            public void onShowCustomView(View view, CustomViewCallback callback) {
                ((VideoWebViewClient) mWebView.getWebViewClient()).onShowCustomView(view, callback);
            }

            public void onHideCustomView() {
                ((VideoWebViewClient) mWebView.getWebViewClient()).onHideCustomView();
            }
        });

        mWebView.loadUrl(mUrl);
    }

    @Override
    public void onBackPressed() {
        if (mWebView.canGoBack()) {
            mWebView.goBack();
        } else {
            super.onBackPressed();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        ViewGroup parent = (ViewGroup) mWebView.getParent();
        if (parent != null) {
            parent.removeView(mWebView);
        }
        mWebView.destroy();
    }
}

在这个示例中，VideoWebViewClient拦截视频链接并启动FullScreenVideoActivity，该Activity中包含了一个WebView，用于播放视频。在播放视频时，将WebView占据整个屏幕并隐藏状态栏、导航栏等UI元素，让视频全屏播放。在Activity销毁时，将WebView从该Activity中移除，并恢复原来的UI状态。