利用 entryAbility 应用证明周期的特点，初始化 store 实例

import UIAbility from '@ohos.app.ability.UIAbility';
import hilog from '@ohos.hilog';
import window from '@ohos.window';
import dataPreferences from '@ohos.data.preferences';
export default class EntryAbility extends UIAbility {
    onCreate(want, launchParam) {
        try{
          dataPreferences.getPreferences(this.context,"myStore",(err,preferences)=>{
            if(err){console.error("报错了");return}
            /*使用 globalThis 方式可以让全局应用公用该属性*/
            globalThis.entryAbilityPreferences = preferences;
          })
        }catch (error){
          console.error("报错了")
        }
    }
}

封装 store 类，src\main\ets\utils\storage.ets

export default class Storage{
  entryAbilityPreferences;
  constructor() {
    this.entryAbilityPreferences = globalThis.entryAbilityPreferences;
  }
  /*设置*/
  setItem(key:string,value:string|number|boolean){
    this.entryAbilityPreferences.has(key,(err, val)=>{
      if(err){console.error("set调用失败");return}
      if(val){console.error("key名已存在")}else{
        try{
          this.entryAbilityPreferences.put(key,value)
          this.entryAbilityPreferences.flush()
        }catch (err){
          console.error("put方法报错了")
        }
      }
    })
  }
  /*查找*/
  getItem(key:string,defaultVal:string|number|boolean):Promise<string|number|boolean>{
    return new Promise((resolve,reject)=>{
      this.entryAbilityPreferences.get(key,defaultVal,(err,val)=>{
        if(err){reject("报错了")}
        resolve(val as string|number|boolean);
      })
    })
  }
  /*删除*/
  delItem(key:string){
    this.entryAbilityPreferences.delete(key)
  }
}

使用

import router from '@ohos.router';
import promptAction from '@ohos.promptAction'
import Storage from "../utils/storage"
​
@Entry
@Component
struct Page {
    storage = new Storage();
    @Builder Header(){
        Row(){
            Button("存储")
            .onclick(async ()=>{
                this.storage.setItem("userName","龚箭") /*写入*/
                let result = await this.storage.getItem("userName","登录") /*读取*/
            })
            
        }
    }
}