请求头部修改；数据回显，用watch数据监听

1.setTimeout，用buid显示

2.数据回显，用watch数据监听


3.请求头部修改

 let qs = require('querystring');
 const res = await this.$http.put('finance/paymentBill/add', this.addForm, {
                headers: {
                    'Content-Type': 'application/json;charset=UTF-8'
                }
            });