@RequestMapping(value = "/login", method = RequestMethod.POST)
public MemberDto login(MemberDto dto, RedirectAttributes re) {
  System.out.println("login()");
  MemberDto member = service.login(dto);

  return member;
}

package bit.com.a.controller;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.InputStreamResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import bit.com.a.util.MediaTypeUtiles;

@RestController
public class FileController {
	
	@Autowired
	private ServletContext servletContext;

	@RequestMapping(value = "/fileUpload", method = RequestMethod.POST)
	public String fileUpload(@RequestParam("uploadFile")MultipartFile uploadFile, HttpServletRequest req) {
		System.out.println("FileController fileUpload");
		
		//경로
		String uploadPath = req.getServletContext().getRealPath("/upload");
		
		//String uploadPath = "d:\\tmp";
		
		String filename = uploadFile.getOriginalFilename();
		String filepath = uploadPath + File.separator + filename; // '/' == file.feparator
		System.out.println("filepath"+filepath);
		
		
		//DB 접근 하는 부분
		
		
		try {
			BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(new File(filepath)));	//파일 생성 -> 파일 아웃풋 -> 버퍼 아웃풋
			bos.write(uploadFile.getBytes());
			bos.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			
			return "file upload fail";
		}
		return "file upload success";
	}
	
  //다운로드
	@RequestMapping(value = "/download") //ResponseEntity 데이터를 한꺼번에 보내줄 수 있다
	public ResponseEntity<InputStreamResource> download(String fileName, HttpServletRequest req)throws Exception{
		System.out.println("FileController fileUpload");
		
		//경로
		String uploadPath = req.getServletContext().getRealPath("/upload");
		
		//String uploadPath = "d:\\tmp";
		
		MediaType mediaType = MediaTypeUtiles.getMediaTypeForFileName(this.servletContext, fileName);
		System.out.println("filename:"+fileName);
		System.out.println("mediaType:"+mediaType);
		
		File file = new File(uploadPath + File.separator+fileName);
		InputStreamResource resource = new InputStreamResource(new FileInputStream(file));
		
		return ResponseEntity.ok()
				.header(HttpHeaders.CONTENT_DISPOSITION, "attachment;filename="+file.getName())
				.contentType(mediaType)
				.contentLength(file.length())
				.body(resource);	//이전 유틸에서 사용 했던 다운로드 창
	}
}

package bit.com.a.util;

import javax.servlet.ServletContext;

import org.springframework.http.MediaType;

public class MediaTypeUtiles {

	public static MediaType getMediaTypeForFileName(ServletContext servletContext, String filename) {
		
		String mimeType = servletContext.getMimeType(filename);
		
		try {
			MediaType mediaType = MediaType.parseMediaType(mimeType);
			return mediaType;	//미디어 타입으로 넘겨준다
		}catch (Exception e) {
			return MediaType.APPLICATION_OCTET_STREAM;
		}
	}
}