Pinia官方文档 

 选项式api

/*
 * @Author: Jackie
 * @Date: 2023-06-25 09:58:10
 * @LastEditTime: 2023-07-24 17:32:25
 * @LastEditors: Jackie
 * @Description: pinia
 * @FilePath: /vue3-demo-pinia/src/store/counter.js
 * @version:
 */
import { defineStore, storeToRefs } from 'pinia';

// 访问user store中数据
import { useUserStore } from './user';

// 你可以对 `defineStore()` 的返回值进行任意命名，但最好使用 store 的名字，同时以 `use` 开头且以 `Store` 结尾。(比如 `useUserStore`，`useCartStore`，`useProductStore`)
// 第一个参数是你的应用中 Store 的唯一 ID。
// export const useCounterStore = defineStore({id:'counter', state:()=> ({ count: 0 })},...)
export const useCounterStore = defineStore('counter', {
  state: () => ({ count: 0, name: 'jackie' }),
  getters: {
    double: (state) => state.count * 2,
    userNum: () => {
      // 获取counter store中数据
      const userSrote = useUserStore();
      const { num } = storeToRefs(userSrote);
      return num.value + '个';
    }
  },
  actions: {
    increment() {
      this.count++;
    }
  },
  persist: {
    enabled: true, // 开启缓存  默认会存储在本地localstorage
    storage: sessionStorage, // 缓存使用方式
    paths: [] // 需要缓存键
    // strategies: [ //自定义key和存储方式
    //   {
    //     key: 'indexStore',
    //     storage: localStorage //可以选择对应的存储形式（localStorage或者sessionStroage）
    //   }
    // ]
  }
});

// 你可以认为 state 是 store 的数据 (data)，getters 是 store 的计算属性 (computed)，而 actions 则是方法 (methods)。

// 可以将状态重置为初始值 $reset()
// store.$reset()

// 可以替换store $state
// store.$state = { name: "℃", age: 22 }

// 使用订阅机制subscribe来实现数据的持久化存储 $subscribe
// store.$subscribe((mutation, state) => {
//   localStorage.setItem(store.$id, JSON.stringify(state));
// });

组合式api

/*
 * @Author: Jackie
 * @Date: 2023-07-24 16:34:03
 * @LastEditTime: 2023-07-24 17:07:20
 * @LastEditors: Jackie
 * @Description: user pinia
 * @FilePath: /vue3-demo-pinia/src/store/user.js
 * @version:
 */
import { defineStore, storeToRefs } from 'pinia';
import { toRefs, ref, reactive, computed } from 'vue';
// 访问counter store数据
import { useCounterStore } from './counter';

export const useUserStore = defineStore(
  'user',
  () => {
    // 状态
    const state = reactive({
      name: 'jackie',
      age: 18
    });
    const num = ref(0);

    // 计算
    const fullName = () => state.name + '' + state.age;
    const Age = computed(() => `年龄：${state.age}-${num.value}岁`);
    // 获取counter store中数据
    const counterSrote = useCounterStore();
    const { count } = storeToRefs(counterSrote);
    const userCount = computed(() => count);

    // 修改
    const setName = (name) => (state.name = name);
    const setAge = (age) => (state.age += age);
    const addNum = () => (num.value += 1);

    return {
      ...toRefs(state),
      num,
      fullName,
      Age,
      setName,
      setAge,
      addNum,
      userCount
    };
  },
  {
    persist: {
      enabled: true, // 开启缓存  默认会存储在本地localstorage
      storage: sessionStorage, // 缓存使用方式
      paths: [] // 需要缓存键
      // strategies: [ //自定义key和存储方式
      //   {
      //     key: 'indexStore',
      //     storage: localStorage //可以选择对应的存储形式（localStorage或者sessionStroage）
      //   }
      // ]
    }
  }
);

demo使用

<!--
 * @Author: Jackie
 * @Date: 2023-06-25 09:58:10
 * @LastEditTime: 2023-07-24 17:39:12
 * @LastEditors: Jackie
 * @Description: file content
 * @FilePath: /vue3-demo-pinia/src/views/HomeView.vue
 * @version: 
-->
<template>
  <div class="home">
    <h1>This is an home page</h1>
    <p>{{ store.count }}</p>
    <p>{{ count }}</p>
    <p>Double count is {{ store.double }}-{{ store.userNum }}</p>
    <p>{{ store }}</p>
    <!-- <p>{{ store.increment }}</p>
    <p>{{ increment }}</p> -->
    <button @click="store.increment">store.Increment</button>
    <hr />
    <p>
      {{ name }}-{{ age }}-{{ num }}-{{ userStore.fullName() }}-{{
        userStore.Age
      }}-{{ userStore.userCount }}
    </p>
    <button @click="userStore.setName('dyh')">setName</button>
    <button @click="userStore.setAge(1)">setAge</button>
    <button @click="userStore.addNum()">addNum</button>
    <p>{{ userStore }}</p>
    <button @click="reset">重置</button>
    <button @click="setName">设置</button>
  </div>
</template>

<script setup>
import { ref, onMounted } from 'vue';
import { storeToRefs } from 'pinia';
import { useCounterStore } from '@/store/counter';
import { useUserStore } from '@/store/user';
const store = useCounterStore();
const userStore = useUserStore();
// const { count } = store; //失去了响应式
const { count } = storeToRefs(store);
const { name, age, num } = storeToRefs(userStore);

// 批量设置
const setName = () => {
  store.$patch({ name: 'dyh', count: 1000 });
  userStore.$patch({ name: 'dyh', age: 1000 });
};
const reset = () => {
  store.$reset();
  userStore.$reset(); //默认setup语法不支持 在main.js中进行配置
};
onMounted(() => {
  console.log(count);
  console.log(name.value, age.value, num.value);
});
</script>

---

解决setup语法下不支持 .$reset() 方法的问题

/*
 * @Author: Jackie
 * @Date: 2023-06-25 09:58:10
 * @LastEditTime: 2023-07-24 17:38:44
 * @LastEditors: Jackie
 * @Description: pinia
 * @FilePath: /vue3-demo-pinia/src/main.js
 * @version:
 */
import { createApp } from 'vue';
import App from './App.vue';
import router from './router';
import { createPinia } from 'pinia';
const pinia = createPinia();
// 为了解决setup语法下不支持 .$reset() 方法的问题
pinia.use(({ store }) => {
  const initialState = JSON.parse(JSON.stringify(store.$state));
  store.$reset = () => {
    store.$state = JSON.parse(JSON.stringify(initialState));
  };
});

// 数据持久化
import piniaPluginPersist from 'pinia-plugin-persist';
pinia.use(piniaPluginPersist);

createApp(App).use(pinia).use(router).mount('#app');