jsp处理文件下载

jsp->java->class，jsp文件解析成java文件（HttpJspBase）再编译成class文件，通过查看java文件，发现在开始文件内容输出前已经out.write("\r\n")两个换行，为什么这两个换行没有跑到下载文件的开头呢？

export.jsp：

<%@page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@page import="java.io.*"%>
<%
response.setHeader("Content-Disposition", "attachment; filename=\"export.txt\"");
PrintWriter pw = response.getWriter();
pw.println("文件内容");
pw.close();
%>

export_jsp.java片段：

_jspxFactory = JspFactory.getDefaultFactory();
response.setContentType("text/html; charset=UTF-8");
pageContext = _jspxFactory.getPageContext(this, request, response,
null, true, 8192, true);
_jspx_page_context = pageContext;
application = pageContext.getServletContext();
config = pageContext.getServletConfig();
session = pageContext.getSession();
out = pageContext.getOut();
_jspx_out = out;

out.write("\r\n");
out.write("\r\n");

response.setHeader("Content-Disposition", "attachment; filename=\"export0"+(session.getAttribute("saveData") != null?2:1)+".txt\"");
PrintWriter pw = response.getWriter();
pw.println("文件内容");
pw.close();