poi生成excel后用ResponseEntity返回流的形式下载

@Controller  //不能是RestController
@RequestMapping("/excel")
public class ExcelController {

    @GetMapping(value = "/export")
    public ResponseEntity<StreamingResponseBody> resultExport() throws Exception {   //需要加上返回的泛型StreamingResponseBody
        List data = new ArrayList();
        String[] header = {"一", "二", "三", "四", "五"};
        Workbook wb = new XSSFWorkbook();
        Sheet sheet = wb.createSheet();
        Row row = sheet.createRow(0);
        for (int i = 0; i < header.length; i++) {
            row.createCell(i).setCellValue(header[i]);
        }
        for (int x = 0; x < data.size(); x++) {
            Row rowNew = sheet.createRow(x + 1);
            //data.get(x);
            rowNew.createCell(0).setCellValue("");
            rowNew.createCell(1).setCellValue("");
            rowNew.createCell(2).setCellValue("");
            rowNew.createCell(3).setCellValue("");
            rowNew.createCell(4).setCellValue("");
        }
        return ResponseEntity.ok()
                .header("Access-Control-Expose-Headers","Content-Disposition")  //不加这一行在跨域情况下前端可能会取不到请求头里的Content-Disposition
                .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=" + URLEncoder.encode(excelName, "UTF-8"))  //文件名
                .body(wb::write);
            /* 上面一行是这一块儿的lambda抽取
            .body(new StreamingResponseBody() {
            @Override
            public void writeTo(OutputStream outputStream) throws IOException {
                wb.write(outputStream);
            }
        });*/
    }

}