import dataPreferences from '@ohos.data.preferences';
import bundleManager from '@ohos.bundle.bundleManager';

本地首選項數(shù)據(jù)的保存，利用key value

【使用要求】

DevEco Studio 3.1.1 Release
api 9

【使用示例】

1、app啟動時，從本地讀取數(shù)據(jù)，并寫到內(nèi)存中去
注意：修改EntryAbility.ts的擴展名，改成ets，即：EntryAbility.ets

import MyPreferencesUtil from '../common/utils/MyPreferencesUtil'
export default class EntryAbility extends UIAbility {
     onCreate(want, launchParam) {
           MyPreferencesUtil.getData(this.context)
     }
 }

2、在修改內(nèi)存數(shù)據(jù)時，再調(diào)用一下保存方法
注意：開發(fā)工具DevEco studio中，默認每次啟動app是先卸載再安裝導致本地保存的數(shù)據(jù)丟失，需要改下配置每次運行都覆蓋安裝【entry-->edit config... --> keep application data】

import {MyPreferencesUtil,UserInfo} from '../common/utils/MyPreferencesUtil'
Button('測試').onClick(()= >{
     console.info('====當前內(nèi)存信息 1 ',JSON.stringify(MyPreferencesUtil.getInstance()))
    MyPreferencesUtil.getInstance().mUserInfo.token = "測試測試"
    MyPreferencesUtil.saveData()
    console.info('====當前內(nèi)存信息 2 ',JSON.stringify(MyPreferencesUtil.getInstance()))
})

export class MyPreferencesUtil {
  //日志過濾器
  private static readonly LOG: string = "====MyPreferencesUtil"
  //本地保存的文件名，和文件內(nèi)的key名這里打算共用一個就行
  private static readonly FILENAME_AND_KEY: string = 'FILENAME_AND_KEY'

  /** 本地要保存的用戶信息 */
  public mUserInfo: UserInfo = new UserInfo()
  // 本地要保存的環(huán)境信息
  public mEnvirInfo: EnvirInfo = new EnvirInfo()
  //=========單例模式，保存數(shù)據(jù)到內(nèi)存實例 start=========
  private static instance: MyPreferencesUtil;

  private constructor() {
  }
  /**
   * 通過單例，獲取本地映射到內(nèi)存中的實例
   * @returns 內(nèi)存中本地數(shù)據(jù)的實例
   */
  public static getInstance() {
    if (this.instance == null) {
      this.instance = new MyPreferencesUtil();
    }
    return this.instance;
  }

單例模式，保存數(shù)據(jù)到內(nèi)存實例

從磁盤本地讀取數(shù)據(jù)到內(nèi)存，賦值給instance

public static async getData(context: Context) {
    try {
      console.info(MyPreferencesUtil.LOG, 'getData');
      let file = await dataPreferences.getPreferences(context, MyPreferencesUtil.FILENAME_AND_KEY)
      console.info(MyPreferencesUtil.LOG, 'getData', 'file succ');
      let value = await file.get(MyPreferencesUtil.FILENAME_AND_KEY, JSON.stringify(MyPreferencesUtil.getInstance()))
      console.info(MyPreferencesUtil.LOG, 'getData', 'get succ', 'value:' + value);
      Object.assign(MyPreferencesUtil.getInstance(), JSON.parse(value.toString()))//將本地數(shù)據(jù) 拷貝到單例中去。
      console.info(MyPreferencesUtil.LOG, 'getData', 'assign succ');
      let bundleFlags = bundleManager.BundleFlag.GET_BUNDLE_INFO_DEFAULT;
      let data = await bundleManager.getBundleInfoForSelf(bundleFlags); //開始保存app的版本名稱和版本號
      MyPreferencesUtil.getInstance().mEnvirInfo.versionName = data.versionName
      MyPreferencesUtil.getInstance().mEnvirInfo.versionCode = data.versionCode
      console.info(MyPreferencesUtil.LOG, 'getData', 'set versionName and versionCode succ');
    } catch (e) {
      console.error(MyPreferencesUtil.LOG, 'getData', JSON.stringify(e));
    }
  }

數(shù)據(jù)備份至磁盤本地

public static async saveData() {
    try {
      console.info(MyPreferencesUtil.LOG, 'saveData');
      let file = await dataPreferences.getPreferences(getContext(this), MyPreferencesUtil.FILENAME_AND_KEY)
      console.info(MyPreferencesUtil.LOG, 'saveData', 'file succ');
      await file.put(MyPreferencesUtil.FILENAME_AND_KEY, JSON.stringify(MyPreferencesUtil.getInstance()))
      console.info(MyPreferencesUtil.LOG, 'saveData', 'put succ');
      await file.flush()
      console.info(MyPreferencesUtil.LOG, 'saveData', 'flush succ');
    } catch (e) {
      console.error(MyPreferencesUtil.LOG, 'saveData', JSON.stringify(e));
    }
  }
}

用戶信息

export class UserInfo {

用戶登錄成功后要保存的token

public token: string = ""
}

環(huán)境信息

export class EnvirInfo {

首次啟動的彈窗是否點擊過“同意”。true:已同意，false:沒同意

public isAgreement: boolean = false

當前app的版本名稱

public versionName: string = ''

當前app的版本號

public versionCode: number = 0
}

審核編輯 黃宇