ServletOutputStream op = response.getOutputStream();
    JszyDao jd=new JszyDao();
    int  fid=0;
    try
    {
     fid=Integer.parseInt(request.getParameter("fid"));
    }catch(Exception ex){
     out.print("数据不存在.");
     return;
    }
    BufferedInputStream is=jd.getJszyIo(fid);
    try{
    int len=0; 
    byte[] buf=new byte[10*1024]; 
    while((len= is.read(buf))!=-1) { 
     op.write(buf, 0, len); 
    } 
     is.close();
     op.flush();
     op.close();
    }catch(Exception ex){
      ex.printStackTrace();
    }