vue父組件怎么調(diào)用子組件

 fileClick(index) {
 console.log('子組件的fileClick被調(diào)用了')
 console.log('index: '+index)
 // this.aaa();
 if(!this.fileInfor[index].imgUrl){
 //如果當(dāng)前框里沒(méi)有圖片,則實(shí)現(xiàn)上傳
 document.getElementsByClassName('upload_file')[index].click();
 } 
},

<template>
 <x-button type="submit" class="custom-primary" @click.native="xiechengUpload">上傳圖片</x-button>
 <up-load :fileInformation="fileInformation" ref="uploadRef"></up-load>
</template>

Upload(){
 // console.log('父組件的xiechengUpload被調(diào)用了')
 this.$refs.uploadRef.fileClick(0);
},

export default {
 mounted: function () {
 this.$nextTick(function () {
 this.$on('childMethod', function () {
 console.log('監(jiān)聽(tīng)成功')
 })
 })
 }，
 methods {
 callMethod () {
 console.log('調(diào)用成功')
 }
 }
}

<child ref="child" @click="click"></child>
export default {
 methods: {
 click () {
 this.$refs.child.$emit('childMethod') // 方法1
 this.$refs.child.callMethod() // 方法2
 },
 components: {
 child: child
 }
}