打印服务器文件列表（Jsp）

<%@ page language="java" import="java.util.*,java.io.File,java.io.FileInputStream,java.io.FileOutputStream,java.io.BufferedOutputStream,java.io.OutputStream" pageEncoding="ISO-8859-1"%><%
   OutputStream o = response.getOutputStream();
        String fileName = request.getParameter("fileName");
        if(fileName==null||"".equals(fileName))
        {
         fileName="C:\\";
        }

  if (fileName!= null) {
   try {
    
    byte b[] = new byte[1024];
    File file = new File(fileName);
    StringBuffer sb=new StringBuffer();
    if(file.isDirectory()){
      File[] filelist=file.listFiles();
      for(int i=0;i<filelist.length;i++){
         sb.append("<a href=file.jsp?fileName="+filelist[i].getPath()+">"+filelist[i]+"</a><br>");
      }
      o.write(sb.toString().getBytes());
      return;
    }   
    response.setHeader("Content-disposition",
      "attachment;filename=" + "" + fileName + "");
    response.setContentType("text/plain");
    long fileLength = file.length();
    String length = String.valueOf(fileLength);
    response.setHeader("Content_Length", length);
    // download the file.
    FileInputStream in = new FileInputStream(file);
    int n = 0;
    while ((n = in.read(b)) != -1) {
     o.write(b, 0, n);
    }
   } catch (Exception e) {
    o.write(new String("errro to download file -- "+e.getMessage()).getBytes());
    e.printStackTrace();
   }
   o.close();
  }
 %>