Android手机上input控件默认设置一个字符串后，然后清除不能触发input事件

<template>
<div>
<text style="font-size: 40px">oninput: {{txtInput}}</text>
<input type="text" placeholder="Input Text" class="input" :value="txtInput" :autofocus=true @input="oninput"/>
</div>
</template>

<style scoped>
.input {
font-size: 60px;
height: 80px;
width: 750px;
}
</style>

<script>
var modal = weex.requireModule('modal')
module.exports = {
data: function () {
return {
txtInput: '外',
};
},
methods: {
oninput: function (event) {
this.txtInput = event.value;
modal.toast({
message: "input: "+event.value
})
}
}
};
</script>