Uploading files in Spring Boot can feel confusing at first — especially when you're dealing with images, documents, or multiple file uploads.

If you've ever struggled with handling file uploads in your backend application, you're not alone.

In this step-by-step guide, you'll learn how to upload single and multiple files in Spring Boot using a simple and clean approach. By the end of this tutorial, you'll be able to build real-world features like profile image upload, document submission, and more.

Learn how to handle file uploads in Spring Boot with real examples, best practices, and clean code

• Upload file API
• Save file to local folder
• Return file response
• Handle multiple file uploads

Technologies Used

• Java 8+
• Spring Boot
• Spring Web
• Multipart File

Step 1: Configure File Upload

Add this in application.properties:

spring.servlet.multipart.enabled=true
spring.servlet.multipart.max-file-size=5MB
spring.servlet.multipart.max-request-size=5MB

Step 2: Create Controller

import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.IOException;
@RestController
@RequestMapping("/file")
public class FileUploadController {
    private final String UPLOAD_DIR = "uploads/";
    @PostMapping("/upload")
    public String uploadFile(@RequestParam("file") MultipartFile file) {
        try {
            File dir = new File(UPLOAD_DIR);
            if (!dir.exists()) dir.mkdirs();
            String filePath = UPLOAD_DIR + file.getOriginalFilename();
            file.transferTo(new File(filePath));
            return "File uploaded successfully: " + filePath;
        } catch (IOException e) {
            return "File upload failed: " + e.getMessage();
        }
    }
}

API Testing

Endpoint

POST /file/upload

Form Data

Key: file Type: File

Output

File uploaded successfully: uploads/sample.jpg

Step 3: Upload Multiple Files

@PostMapping("/upload-multiple")
public String uploadMultiple(@RequestParam("files") MultipartFile[] files) {
    for (MultipartFile file : files) {
        try {
            file.transferTo(new File("uploads/" + file.getOriginalFilename()));
        } catch (IOException e) {
            return "Error: " + e.getMessage();
        }
    }
    return "All files uploaded successfully";
}

Important Tips

• Validate file size
• Allow only specific file types
• Avoid duplicate file names
• Store files securely

Real-World Use Case

• Profile image upload
• Document submission
• Resume upload
• Product images

File upload is a must-have feature in most applications. Spring Boot makes it simple using MultipartFile.

With this setup, you can easily handle both single and multiple file uploads.

Try extending this by uploading files to cloud storage like AWS S3 or Google Cloud.

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