Java创建文件夹和JSP下载文件

一个很简明的小例子：

File dir=new File(“路径”);if(!dir.exists())dir.mkdir();

一个简明的小例子：

String filedisplay = session.getAttribute("username")+"的报表.xls";  filedisplay = URLEncoder.encode(filedisplay,"UTF-8");  response.addHeader("Content-Disposition","attachment;filename=" + filedisplay);    java.io.OutputStream outp = null;  java.io.FileInputStream in = null;  try  {  outp = response.getOutputStream(); in = new FileInputStream(file);    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;  }  if(outp != null){  outp.close();  outp = null;  }  }