解决java使用axios.js的post请求后台时无法接收到入参的问题

getBarCode : _ => {
   let param = new URLSearchParams();
   param.append("userName","admin");
   param.append("userPassword","admin");
   axios.post("/index.html",param)
   .then(function(response){
     console.log(response);
   })
   .catch(function(response){
     console.log(response)
   })
}

//请求后台数据之前转换入参
transformRequest: function (data) {
  let ret = ''
  for (let it in data) {
  ret += encodeURIComponent(it) + '=' + encodeURIComponent(data[it]) + '&'
    }
  return ret
}

axios.post(url,this.transformRequest(param),{
        headers: {
          'Content-Type': 'application/x-www-form-urlencoded;charset=utf-8'
        }
      }).then(function(res){
        console.log(res);
      }).catch(function(res){
        console.log(res);
      })