小程序-下载文件的方式

正常下载的时候，出现下载的时候空白，基本是格式出现问题，或者是文件名出现问题。文件不能是中文

写法

function getOpenId(mName, success, fail) {
  if (mName == 'sms') {
    success();
  } else if (app.globalData.isFirst == 1) {
    wx.login({
      success: function (res) {
        wx.request({
          url: httpUrl + mothod['getOpenId'],
          method: "GET",
          data: {
            code: res.code
          },
          success: function (res) {
            var rData = res.data;
            if (rData.code == 200) {
              app.globalData.isOne = 0;
              app.globalData.openid = retData.openid;
              app.globalData.sessionId = retData.sessionId;
 
              if (app.globalData.openid) {
                success();
              } else {
                fail();
              }
            } else {
              fail(rData);
            }
          }
        });
      },
      error: () => {}
    });
  } else {
    success();
  }
}

const downloadFile = (interfaceName, fileName, success, params) => {
  wx.showLoading({ title: '下载中' });
  let originURL = httpUrl + interfaceName // '你的接口名';
  if(params) originURL += params;
  
  let filePath = `${wx.env.USER_DATA_PATH}/${fileName}`;
  getOpenId(interfaceName,function () { // 没有验证方法也可以
    wx.downloadFile({
      url: originURL,
      filePath: filePath,
      header: {
        'sessionId': getStorage('u_token'),
      },
      success: (res) => {
        wx.hideLoading();
        if(res.statusCode == 200) {
          if (success) {
            success(res);
          }
        }
      },
      fail: (res) => {
        wx.showToast({
          title: '下载失败',
          icon: 'none',
        });
      },
    });
  })
};

  exportFiles: function() {
    const that = this;
    const url = '你的接口名';

    const data = this.data;
    
　　 const getTimes = (new Date()).getTime();
    const fileName = getTimes+'文件名.pdf'; // 文件格式错误，会出现接口红白，但是下载文件打开错误

    const params = `?getTimes=${getTimes}`

  
    https.downloadFile(url, fileName,
      (res) => {
        fileValue.data = res.filePath;
        that.setData({
          fileValue,
        });

        that.onSaveDocument(res.filePath, () => {
          wx.openDocument({
            filePath: res.filePath,
            showMenu: true,
          });
        });
      },
      params
    )
  },

  onSaveDocument(pathval, callback) {
    wx.getSystemInfo({
      success: function (res) {
        if (res.platform === 'windows') {
          wx.saveFileToDisk({
            filePath: pathval,
          })
        } else callback()
      }
    });
  },