Activiti导出模型文件xml(xml文件超过10K)，activiti6导出模型是浏览器直接打开

Activiti导出超过10K的xml文件时，response 要在获取输出流之前设置header格式
原代码为:

ByteArrayInputStream in = new ByteArrayInputStream(exportBytes);
IOUtils.copy(in, response.getOutputStream());
response.setHeader("Content-Disposition", "attachment; filename="+ filename);
response.flushBuffer();

修改后，代码为：

ByteArrayInputStream in = new ByteArrayInputStream(exportBytes);
response.setHeader("Content-Disposition", "attachment; filename="+ filename);
IOUtils.copy(in, response.getOutputStream());
response.flushBuffer();