file download controller for Spring Boot

FileDownload.java

package com.example.thymeleaf;

import java.io.File;
import java.io.FileInputStream;
import java.net.URLEncoder;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseStatus;

@Controller
public class TestController {	

  @RequestMapping("/filedownload")
  @ResponseStatus(HttpStatus.OK)	// Thymeleaf 사용시 이것을 사용해야 에러가 발생하지 않음
  public void fileDownloadOnWebBroweser(HttpServletRequest req, HttpServletResponse res) throws Exception  {

    File f = new File("track.pptx");

    String downloadName = null;
    String browser = req.getHeader("User-Agent");
    //파일 인코딩
    if(browser.contains("MSIE") || browser.contains("Trident") || browser.contains("Chrome")){
      //브라우저 확인 파일명 encode  		             
      downloadName = URLEncoder.encode(f.getName(), "UTF-8").replaceAll("\\+", "%20");		             
    }else{		             
      downloadName = new String(f.getName().getBytes("UTF-8"), "ISO-8859-1");

    }        
    res.setHeader("Content-Disposition", "attachment;filename=\"" + downloadName +"\"");             
    res.setContentType("application/octer-stream");
    res.setHeader("Content-Transfer-Encoding", "binary;");

    try(FileInputStream fis = new FileInputStream(f);
        ServletOutputStream sos = res.getOutputStream();	){

      byte[] b = new byte[1024];
      int data = 0;

      while((data=(fis.read(b, 0, b.length))) != -1){		             
        sos.write(b, 0, data);		             
      }

      sos.flush();
    } catch(Exception e) {
      throw e;
    }

  }

}