getAllVolumes(): Promise<Array<Volume>>，异步获取当前外置存储中所有卷设备信息，以promise方式返回。

我的源码：

import volumemanager from "@ohos.file.volumeManager";

@Entry
@Component
struct TFCardTest {
  @State scanRes: Array<volumemanager.Volume> = []


  TFScan() {

    let rec: Array<volumemanager.Volume> = []

    volumemanager.getAllVolumes().then(function (volumes) {

      if (volumes.length > 0) {
        rec = volumes
        console.info( rec[0].id)
        console.log('rec长度'+rec.length.toString());

        console.info("success11")
      }
    }).catch(function (error) {
      console.info("getAllVolumes failed" + JSON.stringify(error))
    });
    console.log('#####################');
    console.log('rec长度'+rec.length.toString());
    console.log('#####################');
  }

  aboutToAppear() {
    this.TFScan()
  }

  build() {
    Column() {

      Button("scan")
        .size({ width: 200, height: 75 })
        .fontSize(30)
        .onClick(() => {
          this.TFScan()
          console.log('scan******************************************');
        })
    }
    .size({ width: '100%', height: '100%' })
  }
}

运行打印log，两次打印rec长度不一致，跳出：volumemanager.getAllVolumes().then(function (volumes) {}，无法获取volumes的值

10-20 15:16:54.185 28165-28165/com.example.kfjs_motherboardtest I A0fefe/JsApp: scan******************************************
10-20 15:16:54.187 28165-28165/com.example.kfjs_motherboardtest I A0fefe/JsApp: vol-179-100
10-20 15:16:54.187 28165-28165/com.example.kfjs_motherboardtest I A0fefe/JsApp: rec长度5
10-20 15:16:54.187 28165-28165/com.example.kfjs_motherboardtest I A0fefe/JsApp: success11
10-20 15:16:54.394 28165-28165/com.example.kfjs_motherboardtest I A0fefe/JsApp: #####################
10-20 15:16:54.394 28165-28165/com.example.kfjs_motherboardtest I A0fefe/JsApp: rec长度0
10-20 15:16:54.394 28165-28165/com.example.kfjs_motherboardtest I A0fefe/JsApp: #####################