response headers 始终是 charset=iso-8859-1

wx.request({       url: app.globalData._server + '/weixin/kuaidi/query',       method: 'POST',       dataType:'json',       // responseType:'arraybuffer',       header: {         "Content-Type": "application/x-www-form-urlencoded"       },       data:{         expCode: SHOPPING_NAME,         expNo: SHOPPING_CODE       },       success: function (res) {         wx.hideLoading();         that.setData({ wulMesge: res.data.data });         console.log(res.data.Traces);       }     });

中文会乱码

我需要utf-8格式的响应，怎么写都是 charset=iso-8859-1，请问大佬怎么解决，多谢