使用输出流时的注意事项

1、在请求时指定响应类型

//导出excel
  exportExcel(data) {
    return request({
      url: '/api/route/export',
      method: 'post',
      data,
      responseType: 'arraybuffer',
    })
  },

2、将数据写入输出流中

@PostMapping("/export")
    public Result exportInfo(@RequestBody JSONObject jsonObject, HttpServletResponse response) throws IOException {
        //根据条件查询数据
        List<Route> list = routeService.selectPage(jsonObject);
        if(CollectionUtils.isEmpty(list)){
            return Result.error(20001,"没有数据");
        }
        if(list.size() > maxExportTotal){
            return Result.error(20001,"导出的数据过大，请输入条件后导出");
        }
        ExcelUtils.exportExcel(list, jsonObject.getString("fileName"),jsonObject.getString("fileName"), Route.class, 
　　　　　　　　　　　　　　　　jsonObject.getString("fileName"), response);
        return null;
    }

public void write(byte[] b) ：将 b.length字节从指定的字节数组写入此输出流。

sos.write("你好".getBytes("utf-8"));

private static void downLoadExcel(String fileName, HttpServletResponse response, Workbook workbook) throws IOException {
        try {
            response.setCharacterEncoding("UTF-8");
            response.setHeader("content-Type", "application/vnd.ms-excel");
            response.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(fileName + ".xlsx", "UTF-8"));
            
　　　　　　　// 将数据写入到输出流中
　　　　　　　workbook.write(response.getOutputStream());
        } catch (Exception e) {
            throw new IOException(e.getMessage());
        }
    }

3、前端使用fileDownload下载

//导出数据
      exportExcel() {
        this.downloadLoading = true
        const fileName = '线路数据导出'
        route.exportExcel({
          fileName,
          siteName: this.listQuery.siteName,
          routeName: this.listQuery.routeName
        }).then(res => {
            console.log(res)
            fileDownload(res, fileName + '.xlsx')
          },
          err => {
            console.log(err)
          }
        ).finally(()=>{
          this.downloadLoading = false
        })
      },
    }

注意：此处是res还是res.data要看前端的request.js中响应拦截器是否进行了处理

// response interceptor
service.interceptors.response.use(
  response => {
    const headers = response.headers

    let res = response.data
    // 此类为下载流文件，不拦截
    if (headers['content-type'] === 'application/octet-stream;charset=utf-8') {
      return res
    }
    if (headers['content-type'] === 'arrayBuffer;charset=UTF-8') {
      return res
    }
    if (headers['content-type'] === 'application/vnd.ms-excel;charset=UTF-8') {
      return res
    }

    if (response.request.responseType === 'arraybuffer') {
      const enc = new TextDecoder('utf-8')
      res = JSON.parse(enc.decode(new Uint8Array(res)))
    }

    // if the custom code is not 20000, it is judged as an error.
    if (res.code !== 20000) {
      Message({
        message: res.msg || 'Error',
        type: 'error',
        duration: 5 * 1000
      })

      // 50008: Illegal token; 50012: Other clients logged in; 50014: Token expired;
      if (res.code === 50008 || res.code === 50012 || res.code === 50014) {
        // to re-login
        MessageBox.confirm('You have been logged out, you can cancel to stay on this page, or log in again', 'Confirm logout', {
          confirmButtonText: 'Re-Login',
          cancelButtonText: 'Cancel',
          type: 'warning'
        }).then(() => {
          store.dispatch('user/resetToken').then(() => {
            location.reload()
          })
        })
      }
      return Promise.reject(new Error(res.msg || 'Error'))
    } else {
      return res
    }
  },
  error => {
    console.log('err' + error) // for debug
    Message({
      message: error.msg,
      type: 'error',
      duration: 5 * 1000
    })
    return Promise.reject(error)
  }
)