Spring Boot file upload 

Uploading files and images via Spring Boot to local storage is an easy process but there are many ways to do so. Here, I show you the most simple and easy method to upload files and images to your local storage with spring boot and FreeMarker template engine in 3 steps.

Step 1

Create a ‘local-storage’ folder in the root directory of your project.

Step 2

Create an HTML form to select the file to upload.

<h1>SpringBoot file upload example</h1>

<#--if the flag has a message it will show-->
<#if flag??>
    <h2 style="color: #a39146">${flag}</h2>
</#if>

<form action="/upload-action" enctype="multipart/form-data" method="post">
    <label>Please select a file</label><br><br>
    <input type="file" name="myfile"><br><br>
    <input type="submit" value="Submit">
</form>

A FreeMarker ‘if’ syntax is present here with a flag variable to prompt success or failed message.

Step 3

Now, we need to create a method to do the upload operation. In the controller class, the uploadAction method is doing so. Here, we are selecting the ‘local-storage’ folder that we created in step 1 to save the file in. With java.nio.file.Files’s copy method the actual saving of the file is done.

@Controller
public class UploadController {


    @GetMapping("/")
    public ModelAndView index() {
        return new ModelAndView("index");
    }


    @PostMapping("/upload-action")
    public ModelAndView uploadAction(@RequestParam("myfile") MultipartFile theFile, Model model) {

        //selecting the local-storage folder to save the files
        String uploadDir = System.getProperty("user.dir") + "\\local-storage\\";

        String fileName = theFile.getOriginalFilename();

        try {
            //saving the file to the selected folder
            Files.copy(theFile.getInputStream(), Paths.get(uploadDir + fileName), StandardCopyOption.REPLACE_EXISTING);

        } catch (IOException e) {
            e.printStackTrace();

            //a friendly flag if the uploading fails
            model.addAttribute("flag", "Upload Failed");
            return new ModelAndView("index");
        }

        model.addAttribute("flag", "Upload Successful, Check the 'local-storage' folder");
        return new ModelAndView("index");
    }
}

When the code catches an exception it is simply returning a flag message of upload failed. If the upload operation is successful, the flag is showing a success message.

Bonus

In the application.properties file, you can set the max file upload size limit and have more control over your spring boot server.

spring.servlet.multipart.max-file-size=512KB

This project can be found at this GitHub repository