Configuring AWS S3 bucket in Spring boot project for file uploading

Amazon's S3 (Simple Storage Service) is a very reliable storage service for uploading and retrieving files. It is very easy to integrate. In this tutorial we will learn how we can integrate AWS S3 bucket into a spring boot project for files uploading.

1. Maven Dependency

First of all we need to add maven dependency for amazon java sdk.

<!-- https://mvnrepository.com/artifact/com.amazonaws/aws-java-sdk -->
<dependency>
   <groupId>com.amazonaws</groupId>
   <artifactId>aws-java-sdk</artifactId>
   <version>1.11.880</version>
</dependency>

Note: Check in mvn central repository for latest version.

2. Credentials

Create an AWS account and get the following credentials.

a.) ENDPOINT_URL

b.) BUCKET_NAME

c.) ACCESS_KEY

d.) SECRET_KEY

3. Create a Controller

Create a Rest Controller to get MultipartFile from the client to upload on the S3 bucket.

4. Intialize amazon Client

Create a Post Construct method to initialize the Amazon client.

@PostConstruct
private void initializeAmazon() {
   AWSCredentials credentials = new BasicAWSCredentials(ACCESS_KEY, SECRET_KEY);
   this.s3client = AmazonS3ClientBuilder.standard().withRegion(Regions.AP_SOUTHEAST_1).withCredentials(new AWSStaticCredentialsProvider(credentials)).build();
}

5. MultipartFile to file

Create a method to convert multipart file to file. So, it can be uploaded on the S3 bucket.

private File convertMultiPartToFile(MultipartFile file) throws IOException {
   File convFile = new File(System.getProperty("java.io.tmpdir") + File.separator +Objects.requireNonNull(file.getOriginalFilename()));
   try {
      file.transferTo(convFile);
      LOGGER.info("File created successfully");
   } catch (IOException e) {
      LOGGER.error("Exception in file convert service");
   }
   return convFile;
}

6. Method to Generate file name

This method will generate a file name for the file by which it can be identified on the S3 bucket.

private String generateFileName(MultipartFile multiPart) {
   return new Date().getTime() + "-" + Objects.requireNonNull(multiPart.getOriginalFilename()).replace(" ", "_");
}

7. Method to upload File

This method uploads the file on the S3 bucket.

private void uploadFileTos3bucket(String fileName, File file) {
   s3client.putObject(
         new PutObjectRequest(BUCKET_NAME, fileName, file).withCannedAcl(CannedAccessControlList.PublicRead));
}

8. Create a service to upload Multipart files on S3

This method takes a MultipartFile as input and uploads that file to the server and return a URL by which we can access that particular file from the browser.

public String uploadFile(MultipartFile multipartFile) {
   String fileUrl = "";
   try {
      LOGGER.info("In amazon file upload");
      File file = convertMultiPartToFile(multipartFile);
      String fileName = generateFileName(multipartFile);
      fileUrl = ENDPOINT_URL + "/" + fileName;
      uploadFileTos3bucket(fileName, file);
      Utils.delete(file);
      return fileUrl;
   } catch (Exception e) {
      LOGGER.error("Error file uploading file", e);
   }
   return null;
}

9. Method to delete the file from the S3 bucket

This method deletes the file from the S3 bucket.

public void deleteFileFromS3Bucket(String fileUrl) {
   String fileName = fileUrl.substring(fileUrl.lastIndexOf('/') + 1);
   s3client.deleteObject(new DeleteObjectRequest(BUCKET_NAME, fileName));
}