组件中条件判断两个子组件：
{ENV_TYPE === 'weapp' &&
<CMap
ref={e => this.mapContainer = e}
onFillStart={this.fillStart}
onLoadVehicles={this.loadVehicles}
step={this.props.step}
start={start}
terminate={terminate}
markers={this.state.markers}
order={updatedOrder}
previewOrderConfig={previewOrderConfig}
screenHeight={this.state.screenHeight}
/>
}

    {ENV_TYPE === 'h5' &&
      <H5Map
        ref={e => this.mapContainer = e}
        screenHeight={this.state.screenHeight}
        step={this.props.step}
        onFillStart={this.fillStart}
      />
    }

在方法中调用：
/**

• 用户点击定位
  **/
  setMapCenterByUser = () => {
  console.log( this.mapContainer) // null
  this.mapContainer && this.mapContainer.setMapCenterByUserLocation(true)
  }
  如果在组件中不是条件判断显示子组件，该方法中能获取到this.mapContainer实例