Javascript 如何将用户代理从默认设置更改为“；舞台灯光/1.2“；要查看android的视频？

我想知道如何更改默认的用户代理（stagefright/1.2（Linux；Android 10）在adroid studio中具有VIDEOVIEW，我已经尝试了许多方法，但我无法获得它，我需要您的帮助，请这里是我的代码

public class WebViewVideoPlayerActivity extends AppCompatActivity {

String Url;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
            WindowManager.LayoutParams.FLAG_FULLSCREEN);

    setContentView(R.layout.activity_webview_video);
    VideoView videoView = findViewById(R.id.videoView);
    Intent i = getIntent();
    Url = i.getStringExtra("videoUrl");
    

    MediaController mediaController = new MediaController(this);
    mediaController.setAnchorView(videoView);
    videoView.setMediaController(mediaController);
    videoView.setOnErrorListener(mOnErrorListener);
    videoView.requestFocus();
    videoView.setVideoURI(Uri.parse(Url));
    videoView.start();
};

}