JSP 文件 下载 代码 (不使用 jsp smart upload 组件) 解决中文名 问题

代码如下：

<%@page language="java" contentType="application/x-msdownload" pageEncoding="gb2312"%>  
<%@ page  import = " java.io.*, java.util.*, java.net.*"%>  
<%   
  response.reset();
  response.setContentType("application/force-download");
  
  String file = request.getParameter("file"); 
  String filename=request.getSession().getServletContext().getRealPath(file);
  
  File f  =   new  File(filename);
  if  (f.exists()  &&  f.canRead()) {
    String downFileName  =   new  String(f.getName().getBytes(),"ISO-8859-1");
    
    String filedownload = filename;   
    String filedisplay = downFileName;   
    
    response.addHeader("Content-Disposition","attachment;filename=" + filedisplay);   
    
    OutputStream outp = null;   
    FileInputStream in = null;   
    try   
    {   
      outp = response.getOutputStream();   
      in = new FileInputStream(filename);   
    
      byte[] b = new byte[1024];   
      int i = 0;   
    
      while((i = in.read(b)) > 0)   
      {   
        outp.write(b, 0, i);   
      }   
      
      outp.flush();   
      out.clear();   
      out = pageContext.pushBody();   
    }   
    catch(Exception e)   
    {   
      System.out.println("Error!");   
      e.printStackTrace();   
    }   
    finally   
    {   
      if(in != null)   
      {   
        in.close();   
        in = null;   
      }     
    } 
  }else{
  	
  	String  str="<mce:script language='javascript'><!--
";   
    str+="function   showmsg(){alert(/"您要下载的文件不存在！/");}";   
    str+="showmsg();
// --></mce:script>";   
    out.println(str);
	}
	 
%>