String root= ServletActionContext.getServletContext().getRealPath(File.separator).replace("\\", File.separator);
String fileName = "download.text";
File file = new File(root + fileName);
in = new FileInputStream(file);
// 设置响应正文的MIME类型
response.setContentType("Content-Disposition;charset=utf-8");
response.setHeader("Content-Disposition", "attachment;" + " filename=\""+ URLEncoder.encode(fileName, "UTF-8") + "\"");
// 把本地文件发送给客户端
out = response.getOutputStream();
int byteRead = 0;
byte[] buffer = new byte[512];
while ((byteRead = in.read(buffer)) != -1)
{
　　out.write(buffer, 0, byteRead);
}
in.close();
out.close();