HarmonyOS MMKV的使用问题

aboutToAppear() { 
  filePath = GlobalContext.getContext().getObject("filesDir") as string 
  cachePath = GlobalContext.getContext().getObject("cacheDir") as string 
  LogUtil.i('aboutToAppear = ' + filePath) 
} 
init() { 
  LogUtil.i('init start ' + filePath) 
  let root = MMKV.initialize(filePath + '/mmkv', cachePath) 
  LogUtil.i('init root = ' + root) 
  this.showMsg('root = ' + root) 
  let context = GlobalContext.getContext().getObject("context") as Context 
  prefrence.getPreferences(context, fileName, (error, preferences) => { 
    preferences.put('key1', 'value1').then() 
    preferences.put('key3', 3).then() 
    preferences.put('key4', 4.012345648979466).then() 
    preferences.put('key2', false).then() 
    preferences.put('key1', 'hello mmkv').then() 
    preferences.getAll() 
      .then((obj) => { 
        LogUtil.e('testPreference allKeys = ' + JSON.stringify(obj)) 
      }) 
  }) 
  let kv = MMKV.getMMKVWithMMapID('imported', MMKV.SINGLE_PROCESS_MODE, "", undefined); 
  kv.clearAll() 
  let callBack: MyICallBack = new MyICallBack(); 
  kv.preferencesToMMKV(context, fileName, callBack); 
}

testBackup() { 
  LogUtil.i('testBackup start ') 
  let backupRootDir = filePath + '/mmkv_backup_3' 
  let mMapID = 'testCrud' 
  let otherDir = filePath + '/mmkv_3' 
  let ret = MMKV.backupOneToDirectory(mMapID, backupRootDir, otherDir); 
  LogUtil.i('testBackup ret ' + ret) 
  if (ret) { 
    let mmkv = MMKV.getBackedUpMMKVWithID(mMapID, MMKV.SINGLE_PROCESS_MODE, 'Tencent MMKV', backupRootDir); 
    LogUtil.i('testBackup check on backup file[' + mmkv.getMMapID() + '] allKeys: ' + mmkv.getAllKeys()); 
  } 
  backupRootDir = filePath + '/mmkv_backup' 
  let temp = MMKV.backupAllToDirectory(backupRootDir) 
  this.showMsg('temp = ' + temp) 
  if (temp > 0) { 
    let mmkv = MMKV.getBackedUpMMKVWithID('imported', MMKV.SINGLE_PROCESS_MODE, "", backupRootDir); 
    LogUtil.i('backup file[' + mmkv.getMMapID() + '] allKeys: ' + mmkv.getAllKeys()); 
    mmkv = MMKV.getBackedUpMMKVWithID('testKotlin', MMKV.SINGLE_PROCESS_MODE, "", backupRootDir); 
    LogUtil.i('backup file[' + mmkv.getMMapID() + '] allKeys: ' + mmkv.getAllKeys()); 
    mmkv = MMKV.getBackedUpMMKVWithID('test/AES_reKey1', MMKV.SINGLE_PROCESS_MODE, "", backupRootDir); 
    LogUtil.i('backup file[' + mmkv.getMMapID() + '] allKeys: ' + mmkv.getAllKeys()); 
  } 
}