页面横屏

android:screenOrientation="landscape"

取消下划线和标题栏

onWindowFocusChanged(true); //全屏方法

import android.os.Build;
import android.view.View;
import android.view.WindowManager;
import androidx.appcompat.app.AppCompatActivity;
public class BaseActivity extends AppCompatActivity {

    //全屏
    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        if (hasFocus) {
            int flags = View.SYSTEM_UI_FLAG_IMMERSIVE
                    | View.SYSTEM_UI_FLAG_LAYOUT_STABLE
                    | View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION
                    | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                    | View.SYSTEM_UI_FLAG_HIDE_NAVIGATION
                    | View.SYSTEM_UI_FLAG_FULLSCREEN;

            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
                getWindow().getDecorView().setSystemUiVisibility(flags);
                getWindow().getAttributes().layoutInDisplayCutoutMode =
                WindowManager.LayoutParams.LAYOUT_IN_DISPLAY_CUTOUT_MODE_SHORT_EDGES;
            } else {
                getWindow().getDecorView().setSystemUiVisibility(flags);
            }
        }
    }

}