React Native 使用 Amplify 進行身份驗證(3) – 記住登入狀態、自動登入

<em>// services/storage.ts</em>
import AsyncStorage from '@react-native-async-storage/async-storage'
<em>/*
 * Copyright 2017-2017 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance with
 * the License. A copy of the License is located at
 *
 *     http://aws.amazon.com/apache2.0/
 *
 * or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
 * CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
 * and limitations under the License.
 */</em>

const MEMORY_KEY_PREFIX = '@StorageService:'
let dataMemory: any = {}

<em>/** @class */</em>
export class MemoryStorageNew {
  static syncPromise: Promise<any> | null = null
  <em>/**
   * This is used to set a specific item in storage
   * @param {string} key - the key for the item
   * @param {object} value - the value
   * @returns {string} value that was set
   */</em>
  static setItem(key: any, value: any) {
    AsyncStorage.setItem(MEMORY_KEY_PREFIX + key, value)
    dataMemory[key] = value
    return dataMemory[key]
  }

  <em>/**
   * This is used to get a specific key from storage
   * @param {string} key - the key for the item
   * This is used to clear the storage
   * @returns {string} the data item
   */</em>
  static getItem(key: string) {
    return Object.prototype.hasOwnProperty.call(dataMemory, key)
      ? dataMemory[key]
      : undefined
  }

  <em>/**
   * This is used to remove an item from storage
   * @param {string} key - the key being set
   * @returns {string} value - value that was deleted
   */</em>
  static removeItem(key: string) {
    AsyncStorage.removeItem(MEMORY_KEY_PREFIX + key)
    return delete dataMemory[key]
  }

  <em>/**
   * This is used to clear the storage
   * @returns {string} nothing
   */</em>
  static clear() {
    dataMemory = {}
    return dataMemory
  }

  <em>/**
   * Will sync the MemoryStorage data from AsyncStorage to storageWindow MemoryStorage
   * @returns {void}
   */</em>
  static sync() {
    if (!MemoryStorageNew.syncPromise) {
      MemoryStorageNew.syncPromise = new Promise((res, rej) => {
        AsyncStorage.getAllKeys((errKeys, keys) => {
          if (errKeys) rej(errKeys)
          const memoryKeys = keys!.filter(key =>
            key.startsWith(MEMORY_KEY_PREFIX)
          )
          AsyncStorage.multiGet(memoryKeys, (err, stores) => {
            if (err) rej(err)
            stores!.map((result, index, store) => {
              const key = store[index][0]
              const value = store[index][1]
              const memoryKey = key.replace(MEMORY_KEY_PREFIX, '')
              dataMemory[memoryKey] = value
            })
            res(true)
          })
        })
      })
    }
    return MemoryStorageNew.syncPromise
  }
}

<em>/** @class */</em>
export default class StorageHelper {
  private storageWindow: any
  <em>/**
   * This is used to get a storage object
   * @returns {object} the storage
   */</em>
  constructor() {
    this.storageWindow = MemoryStorageNew
  }

  <em>/**
   * This is used to return the storage
   * @returns {object} the storage
   */</em>
  getStorage() {
    return this.storageWindow
  }
}