try {
            response.setContentType("text/plain:charset=GBK");
            response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
            byte[] bytes = logDetails.getBytes();
            ServletOutputStream outStream = response.getOutputStream();
            outStream.write(bytes);
            outStream.flush();
            outStream.close();
        } catch (Exception e) {
            log.debug("保存文件出错: " + e.getMessage());
        }

------解决方案--------------------
同意楼上，response直接读出数据，再设置response.addHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");
就可以保存了。