SpringBoot Upload/Download Files Example – MultipartFile + Thymeleaf + Bootstrap 4

In the tutorial, we guide how to build a SpringBoot web-application to upload/download file with Thymeleaf engine and Bootstrap 4.

Technologies

• Java 8
• Maven 3.6.1
• Spring Tool Suite: Version 3.9.4.RELEASE
• Spring Boot: 2.0.2.RELEASE
• Bootstrap 4

Goal

We create a SpringBoot project as below:

-> Upload Form:

-> Download Form:

Practice

We create a SpringBoot project with below dependencies:

	org.springframework.boot
	spring-boot-starter-thymeleaf


	org.springframework.boot
	spring-boot-starter-web

Frontend

Upload Multipart-Form

– Create /templates/multipartfile/uploadfile.html file:

    
    
    
	%MINIFYHTMLefdb26fd87848454c7a56742a0fb137e14%%MINIFYHTMLefdb26fd87848454c7a56742a0fb137e15%%MINIFYHTMLefdb26fd87848454c7a56742a0fb137e16%
 

	

	

		

			

				
Upload MultipartFile to FileSystem
				

					

						Upload File:
						
					
					Upload
					Files
				
				

					
				
			
		
	
	
%MINIFYHTMLefdb26fd87848454c7a56742a0fb137e17%

Retrieves Files

– Create /templates/multipartfile/listfiles.html file:

    
    
    
	%MINIFYHTMLefdb26fd87848454c7a56742a0fb137e18%%MINIFYHTMLefdb26fd87848454c7a56742a0fb137e19%%MINIFYHTMLefdb26fd87848454c7a56742a0fb137e20%


	

		

			

				
Uploaded Files
				

					

						

							
No
							
Filename
							
Download
						
					
					

						

					        
1
							
File-Name
					        
Link
					    
					
				
				

					Back to Upload Form
				
			
		
	

Backend

File Storage Service

– Create interface FileStorage.java file:

package com.javasampleapproach.multipartfile.filestorage;

import java.nio.file.Path;
import java.util.stream.Stream;

import org.springframework.core.io.Resource;
import org.springframework.web.multipart.MultipartFile;

public interface FileStorage {
	public void store(MultipartFile file);
	public Resource loadFile(String filename);
	public void deleteAll();
	public void init();
	public Stream loadFiles();
}

– Implement above interface by class FileStorageImpl.java:

package com.javasampleapproach.multipartfile.filestorage;

import java.io.IOException;
import java.net.MalformedURLException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.stream.Stream;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.io.Resource;
import org.springframework.core.io.UrlResource;
import org.springframework.stereotype.Service;
import org.springframework.util.FileSystemUtils;
import org.springframework.web.multipart.MultipartFile;

@Service
public class FileStorageImpl implements FileStorage{
	
	Logger log = LoggerFactory.getLogger(this.getClass().getName());
	private final Path rootLocation = Paths.get("filestorage");
 
	@Override
	public void store(MultipartFile file){
		try {
            Files.copy(file.getInputStream(), this.rootLocation.resolve(file.getOriginalFilename()));
        } catch (Exception e) {
        	throw new RuntimeException("FAIL! -> message = " + e.getMessage());
        }
	}
	
	@Override
    public Resource loadFile(String filename) {
        try {
            Path file = rootLocation.resolve(filename);
            Resource resource = new UrlResource(file.toUri());
            if(resource.exists() || resource.isReadable()) {
                return resource;
            }else{
            	throw new RuntimeException("FAIL!");
            }
        } catch (MalformedURLException e) {
        	throw new RuntimeException("Error! -> message = " + e.getMessage());
        }
    }
    
	@Override
    public void deleteAll() {
        FileSystemUtils.deleteRecursively(rootLocation.toFile());
    }

	@Override
    public void init() {
        try {
            Files.createDirectory(rootLocation);
        } catch (IOException e) {
            throw new RuntimeException("Could not initialize storage!");
        }
    }

	@Override
	public Stream loadFiles() {
        try {
            return Files.walk(this.rootLocation, 1)
                .filter(path -> !path.equals(this.rootLocation))
                .map(this.rootLocation::relativize);
        }
        catch (IOException e) {
        	throw new RuntimeException("\"Failed to read stored file");
        }
	}
}

Upload/Download File Controller

– Firstly, create a simple data model FileInfo.java that contains information of a file:

package com.javasampleapproach.multipartfile.model;

public class FileInfo {
	private String filename;
	private String url;
	
	public FileInfo(String filename, String url) {
		this.filename = filename;
		this.url = url;
	}
	
	public String getFilename() {
		return this.filename;
	}
	
	public void setFilename(String filename) {
		this.filename = filename;
	}
	
	public String getUrl() {
		return this.url;
	}
	
	public void setUrl(String url) {
		this.url = url;
	}
}

– Implement controller UploadFileController.java:

package com.javasampleapproach.multipartfile.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.multipart.MultipartFile;

import com.javasampleapproach.multipartfile.filestorage.FileStorage;

@Controller
public class UploadFileController {
	
	@Autowired
	FileStorage fileStorage;
	
    @GetMapping("/")
    public String index() {
        return "multipartfile/uploadform.html";
    }
    
    @PostMapping("/")
    public String uploadMultipartFile(@RequestParam("uploadfile") MultipartFile file, Model model) {
		try {
			fileStorage.store(file);
			model.addAttribute("message", "File uploaded successfully! -> filename = " + file.getOriginalFilename());
		} catch (Exception e) {
			model.addAttribute("message", "Fail! -> uploaded filename: " + file.getOriginalFilename());
		}
        return "multipartfile/uploadform.html";
    }
    
    
}

– Implement controller DownloadFileController.java:

package com.javasampleapproach.multipartfile.controller;

import java.util.List;
import java.util.stream.Collectors;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.Resource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder;

import com.javasampleapproach.multipartfile.filestorage.FileStorage;
import com.javasampleapproach.multipartfile.model.FileInfo;

@Controller
public class DownloadFileController {

	@Autowired
	FileStorage fileStorage;
	
	/*
	 * Retrieve Files' Information
	 */
	@GetMapping("/files")
	public String getListFiles(Model model) {
		List fileInfos = fileStorage.loadFiles().map(
					path ->	{
						String filename = path.getFileName().toString();
						String url = MvcUriComponentsBuilder.fromMethodName(DownloadFileController.class,
		                        "downloadFile", path.getFileName().toString()).build().toString();
						return new FileInfo(filename, url); 
					} 
				)
				.collect(Collectors.toList());
		
		model.addAttribute("files", fileInfos);
		return "multipartfile/listfiles";
	}
 
    /*
     * Download Files
     */
	@GetMapping("/files/{filename}")
	public ResponseEntity downloadFile(@PathVariable String filename) {
		Resource file = fileStorage.loadFile(filename);
		return ResponseEntity.ok()
					.header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + file.getFilename() + "\"")
					.body(file);	
	}
}

Note:
We can configure multipart.max-file in application.properties to limit the size of uploaded file:

spring.http.multipart.max-file-size=500KB
spring.http.multipart.max-request-size=500KB

Run & Check Results

Run the SpringBoot project, then makes upload/download requests ->

Upload File

-> Browser Network logs:

-> Stored files:

Retrieve Files

Download Files

-> Browser Network logs:

SourceCode

SpringUploadDownloadMultipartFile

Last updated on April 8, 2019.