File Upload in Spring MVC

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <property name="maxUploadSize" value="10485760"/> <!-- 10MB -->
</bean>

public class FileUpload {
    private String description;
    private MultipartFile file;  // This will hold the uploaded file
    
    // getters and setters
}

@Controller
public class FileUploadController {
    
    // Show upload form
    @GetMapping("/upload")
    public String showUploadForm(Model model) {
        model.addAttribute("fileUpload", new FileUpload());
        return "upload-form";
    }
    
    // Handle file upload
    @PostMapping("/upload")
    public String handleFileUpload(
            @ModelAttribute FileUpload fileUpload,
            BindingResult bindingResult,
            RedirectAttributes redirectAttributes) {
        
        MultipartFile file = fileUpload.getFile();
        
        if (file.isEmpty()) {
            bindingResult.rejectValue("file", "error.file", "File cannot be empty");
            return "upload-form";
        }
        
        try {
            // Save file to disk or database
            String fileName = file.getOriginalFilename();
            String uploadDir = "uploads/";
            File dest = new File(uploadDir + fileName);
            file.transferTo(dest);
            
            redirectAttributes.addFlashAttribute("message", "File uploaded successfully: " + fileName);
            
        } catch (IOException e) {
            bindingResult.rejectValue("file", "error.file", "File upload failed");
            return "upload-form";
        }
        
        return "redirect:/upload-success";
    }
    
    @GetMapping("/upload-success")
    public String uploadSuccess() {
        return "upload-success";
    }
}

<form action="/upload" method="post" enctype="multipart/form-data">
    <label>Description:</label>
    <input type="text" name="description"/><br/>
    
    <label>Choose file:</label>
    <input type="file" name="file"/><br/>
    
    <button type="submit">Upload</button>
</form>

• Use MultipartFile to handle file uploads in Spring MVC.
• Form must have enctype="multipart/form-data".
• Configure multipartResolver for file upload support.
• transferTo() saves the file to disk.
• Validate file size and type before processing.