java下载文件并设置格式

public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {File filename = new File("D:\\chengxu\\ML\\2.excel");//设置文件ContentType类型，这样设置，会自动判断下载文件类型  response.setContentType("multipart/form-data");//设置编码格式response.setCharacterEncoding("UTF-8");  //设置可以识别Html文件  response.setContentType("text/html");// 2.设置文件头：最后一个参数是设置下载文件名  response.setHeader("Content-Disposition", "attachment;filename="+filename.getName());//（这里  可以设置成excel格式 ：response.setHeader("Content-Disposition", "attachment;fileName=" + “文件名” + ".xsl");//可以设置成.pdf格式 ：response.setHeader("Content-Disposition", "attachment;fileName=" + “文件名” + ".pdf");OutputStream out = response.getOutputStream();FileInputStream fileinput = new FileInputStream(filename);try {out = response.getOutputStream();  int b = 0;  byte[] buffer = new byte[1024];  while ((b = fileinput.read(buffer)) != -1) {  // 4.写到输出流(out)中  out.write(buffer, 0, b);  }  } catch (Exception  e) {e.printStackTrace();}finally{fileinput.close();  out.flush();  out.close();  }  
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