wx.downloadFile({
        url: this.data.cardImg,
        success:(res)=>{
          let img = res.tempFilePath;
          console.log(img)
          wx.saveImageToPhotosAlbum({
            filePath: img,
            success:(rs)=>{
              wx.showToast({
                title: '保存图片成功',
                icon:'none'
              })
            },
            fail:()=>{
              wx.showToast({
                title: '保存图片失败',
                icon:'none'
              })
            }
          })
        }
      })