1、基础知识
类别引用说明:订阅报纸。用户作为订阅者订购报纸,邮局派送报纸。
1、一种组件间通信的方式,适用于<span style="color:red">任意组件间通信</span>。
2、使用步骤:
-
安装pubsub:
npm i pubsub-js
(安装不成功、使用管理员权限运行) -
引入:
import pubsub from 'pubsub-js'
(订阅和发布都要引入)
3、接收数据:A组件想接收数据,则在A组件中订阅消息,订阅的<span style="color:red">回调留在A组件自身。</span>
methods(){
demo(data){......}
}
......
mounted() {
this.pid = pubsub.subscribe('xxx',this.demo) //订阅消息
}
4、提供数据:pubsub.publish('xxx',数据)
(这里的传参传两个、第一个是订阅名、第二个是数据)
5、最好在beforeDestroy钩子中,用PubSub.unsubscribe(pid)
去<span style="color:red">取消订阅。</span>
2、代码实例
实现的效果:student组件中的信息发送到School组件中。student作为信息的发布者,School组件订阅信息。
2.1 main.js
//引入Vue
import Vue from 'vue'
//引入App
import App from './App.vue'
//关闭Vue的生产提示
Vue.config.productionTip = false
//创建vm
new Vue({
el:'#app',
render: h => h(App),
})
<hr>
2.2 School.vue
<template>
<div class="school">
<h2>学校名称:{{name}}</h2>
<h2>学校地址:{{address}}</h2>
</div>
</template>
<script>
import pubsub from 'pubsub-js'
export default {
name:'School',
data() {
return {
name:'尚硅谷',
address:'北京',
}
},
mounted() {
// console.log('School',this)
/* this.$bus.$on('hello',(data)=>{
console.log('我是School组件,收到了数据',data)
}) */
this.pubId = pubsub.subscribe('hello',(msgName,data)=>{
console.log(this)
// console.log('有人发布了hello消息,hello消息的回调执行了',msgName,data)
})
},
beforeDestroy() {
// this.$bus.$off('hello')
pubsub.unsubscribe(this.pubId)
},
}
</script>
<style scoped>
.school{
background-color: skyblue;
padding: 5px;
}
</style>
<hr>
2.3 Student.vue
<template>
<div class="student">
<h2>学生姓名:{{name}}</h2>
<h2>学生性别:{{sex}}</h2>
<button @click="sendStudentName">把学生名给School组件</button>
</div>
</template>
<script>
import pubsub from 'pubsub-js'
export default {
name:'Student',
data() {
return {
name:'张三',
sex:'男',
}
},
mounted() {
// console.log('Student',this.x)
},
methods: {
sendStudentName(){
// this.$bus.$emit('hello',this.name)
pubsub.publish('hello',666)
}
},
}
</script>
<style lang="less" scoped>
.student{
background-color: pink;
padding: 5px;
margin-top: 30px;
}
</style>
<hr>
2.4 App.vue
<template>
<div class="app">
{{msg}}
<School/>
<Student/>
</div>
</template>
<script>
import Student from './components/Student'
import School from './components/School'
export default {
name:'App',
components:{School,Student},
data() {
return {
msg:'你好啊!',
}
}
}
</script>
<style scoped>
.app{
background-color: gray;
padding: 5px;
}
</style>
3、全局事件总线通信改为消息的订阅和发布
3.1 核心部分代码
这里只修改一处、删除列表项的数据方式改为消息订阅和发布的形式
3.1.1 TheItem.vue(样式省略)、发布消息
消息发布、将要删除的id传递给App.vue
<template>
<li>
<label>
<input
type="checkbox"
:checked="todo.done"
@change="handleCheck(todo.id)"
/>
<span>{{ todo.title }}</span>
</label>
<button class="btn btn-danger" @click="handleDelete(todo.id)">删除</button>
</li>
</template>
<script>
import pubsub from 'pubsub-js'
export default {
name: "MyItem",
//声明接收todo、checkTodo、deleteTodo
props: ["todo"],
methods: {
//勾选or取消勾选
handleCheck(id) {
//通知App组件将对应的todo对象的done值取反
// this.checkTodo(id);
this.$bus.$emit('checkTodo',id)
},
//删除
handleDelete(id) {
if (confirm("确定删除吗?")) {
//通知App组件将对应的todo对象删除
// this.deleteTodo(id);
// this.$bus.$emit('deleteTodo',id)
// 消息发布
pubsub.publish('deleteTodo',id)
}
},
},
};
</script>
<hr>
3.1.2 App.vue 订阅消息
<template>
<div >
<div class="todo-container">
<div class="todo-wrap">
<TheHeader @addTodo="addTodo" />
<TheList :todos="todos" />
<TheFooter
:todos="todos"
@checkAllTodo="checkAllTodo"
@clearAllTodo="clearAllTodo"
/>
</div>
</div>
</div>
</template>
<script>
import TheHeader from "./components/TheHeader";
import TheList from "./components/TheList";
import TheFooter from "./components/TheFooter.vue";
import pubsub from "pubsub-js";
export default {
name: "App",
components: { TheHeader, TheList, TheFooter },
data() {
return {
msg: "你好啊!",
studentName: "",
//由于todos是MyHeader组件和MyFooter组件都在使用,所以放在App中(状态提升)
todos: JSON.parse(localStorage.getItem("todos")) || [],
// todos: [
// { id: "001", title: "吃饭", done: true },
// { id: "002", title: "睡觉", done: false },
// { id: "003", title: "打豆豆", done: true },
// ],
};
},
methods: {
//添加一个todo
addTodo(todoObj) {
this.todos.unshift(todoObj);
},
//勾选or取消勾选一个todo
checkTodo(id) {
this.todos.forEach((todo) => {
if (todo.id === id) todo.done = !todo.done;
});
},
//删除一个todo
deleteTodo(_, id) {
this.todos = this.todos.filter((todo) => todo.id !== id);
},
//全选or取消全选
checkAllTodo(done) {
this.todos.forEach((todo) => {
todo.done = done;
});
},
//清除所有已经完成的todo
clearAllTodo() {
this.todos = this.todos.filter((todo) => {
return !todo.done;
});
},
},
watch: {
todos: {
deep: true,
handler(value) {
localStorage.setItem("todos", JSON.stringify(value));
},
},
},
mounted() {
this.$bus.$on("checkTodo", this.checkTodo);
// this.$bus.$on('deleteTodo',this.checkTodo)
//订阅消息、调用方法里边的函数、参数两个。第一个订阅消息名称、第二个是数据。也可以直接写成箭头函数
this.pubId = pubsub.subscribe("deleteTodo", this.deleteTodo);
},
beforeDestroy() {
this.$bus.$off("checkTodo");
// this.$bus.$off('deleteTodo')
// 取消订阅
pubsub.unsubscribe(this.pubId);
},
};
</script>
<hr>