wx.downloadFile({
      url: confirmationUrl,//confirmationUrl图片地址
      success: (res) => {
        wx.saveImageToPhotosAlbum({
          filePath: res.tempFilePath,
          success: (res) => {
            wx.showToast({
              title: '保存成功',
              duration:1000,
            })
          },
          fail: (err) => {
            wx.showToast({
              title: '获取权限失败',
              duration:1000,
            })
          }
        })
      }
    })