ReactNative 阻止点击返回按钮时返回

import {
    View,
    Text,
    BackHandler,
    ToastAndroid,
} from 'react-native';

class BackButtonDemo extends Component {
    componentDidMount() {
        BackHandler.addEventListener('hardwareBackPress', this.handleBackButton);
    }

    componentWillUnmount() {
        BackHandler.removeEventListener('hardwareBackPress', this.handleBackButton);
    }

    handleBackButton() {
        ToastAndroid.show('Back button is pressed', ToastAndroid.SHORT);
        return true;
    }

}