downFile:function (fileName){

        wx.downloadFile({

            url: app.globalData.prex + '/common/download?fileName='+fileName+'&delete='+true, 

            success (res) {

              // 只要服务器有响应数据，就会把响应内容写入文件并进入 success 回调，业务需要自行判断是否下载到了想要的内容

              if (res.statusCode === 200) {

                wx.saveFile({

                    tempFilePath: res.tempFilePath,

                    success (res) {

                        console.log(JSON.stringify(res));

                        wx.openDocument({

                            filePath: res.savedFilePath,

                            fileType:'xlsx',

                            success(res){

                                console.log('res'+JSON.stringify(res))

                            },

                            fail(error){

                                console.log('错误'+JSON.stringify(error))

                            }

                        })

                    },

                    fail(error){

                        Toast('下载失败')

                    }

                })

              }

            }

          })

    },