在Android 9和更高版本上使用MediaProjection时，需要添加一些额外的权限和代码。

首先，在AndroidManifest.xml文件中添加以下权限：

然后，创建一个Service类来获取MediaProjection：

public class MediaProjectionService extends Service {
    private MediaProjectionManager mProjectionManager;
    private MediaProjection mMediaProjection;

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        mProjectionManager = (MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE);
        Intent captureIntent = mProjectionManager.createScreenCaptureIntent();
        startActivityForResult(captureIntent, REQUEST_CODE_CAPTURE);
        return START_NOT_STICKY;
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQUEST_CODE_CAPTURE && resultCode == RESULT_OK) {
            mMediaProjection = mProjectionManager.getMediaProjection(resultCode, data);
            // 在这里可以使用MediaProjection进行屏幕捕捉
        }
        stopSelf();
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

在你的Activity中，启动Service来获取MediaProjection：

public class MainActivity extends AppCompatActivity {
    private static final int REQUEST_CODE_MEDIA_PROJECTION = 1;

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

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            MediaProjectionManager mediaProjectionManager = (MediaProjectionManager) getSystemService(Context.MEDIA_PROJECTION_SERVICE);
            Intent permissionIntent = mediaProjectionManager.createScreenCaptureIntent();
            startActivityForResult(permissionIntent, REQUEST_CODE_MEDIA_PROJECTION);
        }
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQUEST_CODE_MEDIA_PROJECTION && resultCode == RESULT_OK) {
            Intent serviceIntent = new Intent(this, MediaProjectionService.class);
            serviceIntent.putExtra("data", data);
            startService(serviceIntent);
        }
    }
}

这样，你就可以在Android 9+上使用MediaProjection进行屏幕捕捉了。