Harmoney Next中首选项的使用方法

import data_preferences from '@ohos.data.preferences';
import { BusinessError } from '@ohos.base';
const PREFERENCES_NAME = "PREFERENCES_NAME" //首选项名称
/**
 * 首选项工具类：key只能是字符串类型，value类型：number | string | boolean | Array<number> | Array<string> | Array<boolean>;
 *
 */
export class PreferencesManager {
  private static localDataManager: PreferencesManager;
  static instance() {
    if (!PreferencesManager.localDataManager) {
      PreferencesManager.localDataManager = new PreferencesManager();
    }
    return PreferencesManager.localDataManager;
  }
  put(context: Context, key: string, value: data_preferences.ValueType) {
    let preferences = data_preferences.getPreferences(context, PREFERENCES_NAME);
    preferences.then((res) => {
      res.put(key, value).then(() => {
        res.flush();
      }).catch((err: BusinessError) => {
      });
    })
  }
  get(context: Context, key: string, callback: Function) {
    let preferences = data_preferences.getPreferences(context, PREFERENCES_NAME);
    preferences.then((res) => {
      res.get(key, undefined).then((value) => {
        callback(value)
      }).catch((err: BusinessError) => {
        callback(undefined)
      });
    });
  }
  delete(context: Context, key: string) {
    let preferences = data_preferences.getPreferences(context, PREFERENCES_NAME);
    preferences.then((res) => {
      res.delete(key).then((value) => {
      });
    });
  }
  clear(context: Context) {
    let preferences = data_preferences.getPreferences(context, PREFERENCES_NAME);
    preferences.then((res) => {
      res.clear().then((value) => {
      });
    });
  }
}

import {PreferencesManager} from './../Common/PreferencesUtils'
//给首选项添加数据
PreferencesManager.instance().put(getContext(this),'user','123')

import {PreferencesManager} from './../Common/PreferencesUtils'
aboutToAppear(): void {
  PreferencesManager.instance().get(getContext(this),'user',(val: preferences.ValueType) => {
    if(!val){ //没有值，跳到登录页
      router.pushUrl({url:"pages/Login"})
    }
    //console.info("Succeeded in getting value of 'startup'. val： " + val);
  })
}