安卓应用如何在整个应用运行期间都禁止弹出输入法面板？

getWindow().setFlags(WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM,
                WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM);

public abstract class BaseNoIMActivity extends AppCompatActivity {
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM,
                WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM);
        onCreateStarted(savedInstanceState);
    }

    protected abstract void onCreateStarted(@Nullable Bundle savedInstanceState);
}

public class TestActivity extends BaseNoIMActivity {//继承基类

    @Override
    protected void onCreateStarted(@Nullable Bundle savedInstanceState) {
        setContentView(R.layout.activity_test);
        Log.e("test","TestActivity is started");
    }
}