Storage Strategy for firebase upload and download with Admin SDK initialization in code

FirebaseStorageStrategyModified.java

@Service
public class FirebaseStorageStrategy implements StorageStrategy {
    private final Logger log = LoggerFactory.getLogger(FirebaseStorageStrategy.class);
    private final Environment environment;

    private StorageOptions storageOptions;
    private String bucketName;
    private String projectId;

    public FirebaseStorageStrategy(Environment environment) {
        this.environment = environment;
    }

    @PostConstruct
    private void initializeFirebase() throws Exception {
        bucketName = environment.getRequiredProperty("FIREBASE_BUCKET_NAME");
        projectId = environment.getRequiredProperty("FIREBASE_PROJECT_ID");

        InputStream firebaseCredential = createFirebaseCredential();
        this.storageOptions = StorageOptions.newBuilder()
                .setProjectId(projectId)
                .setCredentials(GoogleCredentials.fromStream(firebaseCredential)).build();

    }

    public String[] uploadFile(MultipartFile multipartFile) throws IOException {
        System.out.println("bucket name====" + bucketName);
        File file = convertMultiPartToFile(multipartFile);
        Path filePath = file.toPath();
        String objectName = generateFileName(multipartFile);

        Storage storage = storageOptions.getService();

        BlobId blobId = BlobId.of(bucketName, objectName);
        BlobInfo blobInfo = BlobInfo.newBuilder(blobId).build();
        Blob blob = storage.create(blobInfo, Files.readAllBytes(filePath));

        log.info("File " + filePath + " uploaded to bucket " + bucketName + " as " + objectName);
        return new String[]{"fileUrl", objectName};
    }


    @Override
    public ResponseEntity<Object> downloadFile(String fileName, HttpServletRequest request) throws Exception {
        Storage storage = storageOptions.getService();

        Blob blob = storage.get(BlobId.of(bucketName, fileName));
        ReadChannel reader = blob.reader();
        InputStream inputStream = Channels.newInputStream(reader);

        byte[] content = null;
        log.info("File downloaded successfully.");

        content = IOUtils.toByteArray(inputStream);

        final ByteArrayResource byteArrayResource = new ByteArrayResource(content);

        return ResponseEntity
                .ok()
                .contentLength(content.length)
                .header("Content-type", "application/octet-stream")
                .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + fileName + "\"")
                .body(byteArrayResource);

    }


    private File convertMultiPartToFile(MultipartFile file) throws IOException {
        File convertedFile = new File(Objects.requireNonNull(file.getOriginalFilename()));
        FileOutputStream fos = new FileOutputStream(convertedFile);
        fos.write(file.getBytes());
        fos.close();
        return convertedFile;
    }

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

    private InputStream createFirebaseCredential() throws Exception {
        FirebaseCredential firebaseCredential = new FirebaseCredential();
        //private key
        String privateKey = environment.getRequiredProperty("FIREBASE_PRIVATE_KEY").replace("\\n", "\n");
        
        firebaseCredential.setType(environment.getRequiredProperty("FIREBASE_TYPE"));
        firebaseCredential.setProject_id(projectId);
        firebaseCredential.setPrivate_key_id("FIREBASE_PRIVATE_KEY_ID");
        firebaseCredential.setPrivate_key(privateKey);
        firebaseCredential.setClient_email(environment.getRequiredProperty("FIREBASE_CLIENT_EMAIL"));
        firebaseCredential.setClient_id(environment.getRequiredProperty("FIREBASE_CLIENT_ID"));
        firebaseCredential.setAuth_uri(environment.getRequiredProperty("FIREBASE_AUTH_URI"));
        firebaseCredential.setToken_uri(environment.getRequiredProperty("FIREBASE_TOKEN_URI"));
        firebaseCredential.setAuth_provider_x509_cert_url(environment.getRequiredProperty("FIREBASE_AUTH_PROVIDER_X509_CERT_URL"));
        firebaseCredential.setClient_x509_cert_url(environment.getRequiredProperty("FIREBASE_CLIENT_X509_CERT_URL"));

        ObjectMapper mapper = new ObjectMapper();
        String jsonString = mapper.writeValueAsString(firebaseCredential);

        //convert jsonString string to InputStream using Apache Commons
        return IOUtils.toInputStream(jsonString);
    }
}