korean
Last Modified 5.4.2025

Download Controller

https://github.com/kimjonghoon/downloadController

How to run

mvn jetty:run
DownloadController.java
package net.java_school.controller;

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

import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import org.springframework.core.io.InputStreamResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.util.FileCopyUtils;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
@RequestMapping("/file")
public class DownloadController {

  private static final String FILE_DIR = "./files/";

  @GetMapping("/download/{filename:.+}")
  public ResponseEntity<InputStreamResource> download(@PathVariable(name="filename") String filename, HttpServletRequest req) throws IOException {

    File file = new File(FILE_DIR + filename);
		
    InputStreamResource resource = new InputStreamResource(new FileInputStream(file));

    boolean ie = req.getHeader("User-Agent").indexOf("MSIE") != -1;
    if (ie) {
      filename = URLEncoder.encode(filename, "UTF-8").replaceAll("\\+", " ");
    } else {
      filename = new String(filename.getBytes("UTF-8"), "8859_1");
    }

    return ResponseEntity.ok()
        .header(HttpHeaders.CONTENT_DISPOSITION, "attachment;filename=\"" + filename + "\"")
        .contentType(MediaType.APPLICATION_OCTET_STREAM).contentLength(file.length())
        .body(resource);
  }
	
  @PostMapping("/download")
  public void download(@RequestParam(name="filename") String filename, HttpServletRequest req, HttpServletResponse resp) {
    OutputStream outputStream = null;

    try {
      File file = new File(FILE_DIR + filename);

      String filetype = filename.substring(filename.indexOf(".") + 1, filename.length());

      if (filetype.trim().equalsIgnoreCase("txt")) {
        resp.setContentType("text/plain");
      } else {
        resp.setContentType("application/octet-stream");
      }

      resp.setContentLength((int) file.length());

      boolean ie = req.getHeader("User-Agent").indexOf("MSIE") != -1;
      if (ie) {
        filename = URLEncoder.encode(filename, "UTF-8").replaceAll("\\+", " ");
      } else {
        filename = new String(filename.getBytes("UTF-8"), "8859_1");
      }

      resp.setHeader("Content-Disposition", "attachment; filename=\"" + filename + "\"");

      outputStream = resp.getOutputStream();
      FileInputStream fis = null;

      try {
        fis = new FileInputStream(file);
        FileCopyUtils.copy(fis, outputStream);
      } finally {
        if (fis!= null) {
          fis.close();
        }
      }
    } catch (IOException e) {
      throw new RuntimeException(e);
    } finally {
      try {
        outputStream.close();
        resp.flushBuffer();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
  }
}
/WEB-INF/views/index.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<title>Home</title>
<meta name="Keywords" content="Download Controller TEST" />
<meta name="Description" content="Download Controller TEST" />
</head>
<body>

<form id="downForm" action="/file/download" method="post">
  <input type="hidden" name="filename" value="Test.png" />
  <input type="submit" value="POST Download" />
</form>

<div><a href="/file/download/Test.png">GET Download</a></div>

</body>
</html>
References