text: import React from 'react';
  import {BackHandler} from 'react-native';
  
  /**
   * Android物理回退键处理
   */
  export default class BackPressComponent {
      constructor(props) {
          this._hardwareBackPress = this.onHardwareBackPress.bind(this);
          this.props = props;
      }
  
      componentDidMount() {
          if (this.props.backPress) BackHandler.addEventListener('hardwareBackPress', this._hardwareBackPress);
      }
  
      componentWillUnmount() {
          if (this.props.backPress) BackHandler.removeEventListener('hardwareBackPress', this._hardwareBackPress);
      }
  
      onHardwareBackPress(e) {
          return this.props.backPress(e);
      }
  }
  