Spring Boot Web Application Upload File

In this tutorial we’re going to learn how to implement file uploading function in a Spring Boot web application.

Creating Spring Boot Project with Spring Tool Suite on Eclipse

Open Spring Tool Suite and go to menu File -> New -> Spring Starter Project.

On the New Spring Starter Project window, input your project information as below screenshot and click Next button.

Spring Boot Web Upload File - New Spring Starter Project

On the New Spring Starter Project Dependencies, choose Thymeleaf and Spring Web then click Finish.

Spring Boot Web Upload File - New Spring Starter Project Dependencies

Creating File Upload Controller

Next step let’s create a new FileUploadController.java as below.

package dev.simplesolution.fileupload;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;

import org.springframework.stereotype.Controller;
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 org.springframework.web.servlet.mvc.support.RedirectAttributes;

@Controller
public class FileUploadController {
	
	private final String UPLOAD_DIRECTORY = "D:\\SimpleSolution\\upload";
	
	@GetMapping("/")
	public String uploadFileForm() {
		return "uploadFileForm";
	}
	
	@PostMapping("/uploadFile")
	public String uploadFile(@RequestParam("file") MultipartFile file, RedirectAttributes redirectAttributes) 
			throws IOException {
		if(file.isEmpty()) {
			redirectAttributes.addFlashAttribute("errorMessage", "Please select a file to upload.");
			return "redirect:/";
		}
		
		Path path = Paths.get(UPLOAD_DIRECTORY, file.getOriginalFilename());
		Files.write(path, file.getBytes());
		redirectAttributes.addFlashAttribute("successMessage", "File upload successfully, uploaded file name: " + file.getOriginalFilename());
		return "redirect:/";
	}
	
}

Creating HTML Views

In directory src/main/resources, create uploadFileForm.html file.

<html xmlns:th="https://www.thymeleaf.org">
<head>
	<title>Spring Boot Web Upload File</title>
	<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css">
</head>
<body>
	<div class="container">
		<p class="text-danger" th:if="${errorMessage}" th:text="${errorMessage}"></p>
		<p class="text-success" th:if="${successMessage}" th:text="${successMessage}"></p>
		<form method="POST" enctype="multipart/form-data" action="/uploadFile">
			<div class="form-group">
		    	<label for="exampleFormControlFile1">File to upload</label>
		    	<input type="file" class="form-control-file" id="file" name="file" >
		  	</div>
		  	<button type="submit" class="btn btn-primary">Upload</button>
		</form>
	</div>
</body>
</html>