网页上传下载的代码，尽量简单请问怎么写，谢谢

网页上传与下载的代码，尽量简单，
上传的行了，但下载的不行
我的下载代码为：但页面都显示不出来，请问怎么改，谢谢
<%@ page contentType="text/html;charset=UTF-8" %>     
<%@ page import = "java.io.*" %>
<%        
//防止IE缓存
response.setHeader("pragma","no-cache");
response.setHeader("cache-control","no-cache");   
response.setDateHeader("Expires",0);
//设置编码
request.setCharacterEncoding("UTF-8");
String fileName = new String(request.getParameter("fileName").getBytes("ISO-8859-1"),"UTF-8");
//取到文件
File file = new File(application.getRealPath("/")+"upload/" + fileName);
   
response.reset();
//response.setContentType("application/octet-stream;charset=UTF-8");
response.setContentType("application/octet-stream;charset=UTF-8");//解决在弹出文件下载框不能打开文件的问题
//System.out.println(response.getCharacterEncoding());
//一定要对fileName进行encode
//response.addHeader("Content-Disposition", "attachment; filename=" + java.net.URLEncoder.encode(fileName, "UTF-8"));
response.addHeader("Content-Disposition", "attachment; filename=" + new String(fileName.getBytes("GBK"),"ISO8859-1"));//解决在弹出文件下载框不能打开文件的问题
response.setContentLength((int) file.length());
byte[] buffer = new byte[4096];
BufferedOutputStream output = null;
BufferedInputStream input = null;

//写缓冲区
try {
      output = new BufferedOutputStream(response.getOutputStream());
      out.clear();
         out = pageContext.pushBody();
      input = new BufferedInputStream(new FileInputStream(file));
      int n = (-1);
      while ((n = input.read(buffer, 0, 4096)) > -1) {
          output.write(buffer, 0, n);
      }
      response.flushBuffer();
}
catch (Exception e) {
}
finally {
      if (input != null) input.close();
      if (output != null) output.close();
}
%>
----------------解决方案--------------------------------------------------------
使用第三方相应类库就简单了。
----------------解决方案--------------------------------------------------------
请问要如何改呢
----------------解决方案--------------------------------------------------------
建议使用 SmartUpload

----------------解决方案--------------------------------------------------------