【React Native】某个页面禁用物理返回键

import {

  BackHandler,

} from ‘react-native‘;

componentDidMount(): void {

      BackHandler.addEventListener(‘hardwareBackPress‘,
        this.onBackButtonPressAndroid);

  }

onBackButtonPressAndroid = () => {
        if (this.props.navigation.isFocused()) {
            if (this.lastBackPressed && this.lastBackPressed + 2000 >= Date.now()) {
                //最近2秒内按过back键，可以退出应用。
                return false;
            }
            this.lastBackPressed = Date.now();
            ToastAndroid.show(‘再按一次退出应用‘, ToastAndroid.SHORT);
            return true;
        }
    }

componentWillUnmount(): void {
        BackHandler.removeEventListener(‘hardwareBackPress‘,
            this.onBackButtonPressAndroid);
    }