<div id="app">
    <comp1></comp1>
    <comp2></comp2>
</div>

let event = new Vue();

Vue.component('comp1', {
    template: `
        <div>
            <p>我是第一个组件</p>
            <input type="text" @keyup="send" v-model="comp1_msg"/>
        </div>
    `,
    data(){
        return {
            comp1_msg: ''
        }
    },
    methods: {
        send(){
            event.$emit('comp1_send', this.comp1_msg);
        }
    }
});

Vue.component('comp2', {
    template: `
        <div>
            <P>我是第二个组件</P>
            <p>{{comp2_msg}}</p>
        </div>
    `,
    data(){
        return {
            comp2_msg: ''
        }
    },
    mounted(){
        let me = this;
        event.$on('comp1_send', function(data){
            me.comp2_msg = data;
        });
    }
});

new Vue({
    el: "#app"
})