Blob.java

import java.io.FileInputStream;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.io.InputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.nio.file.*;

public class Blob {
    private static String sha1 = "";

    public static String calculateSHA1(String filePath) throws IOException, NoSuchAlgorithmException {
        MessageDigest sha1Digest = MessageDigest.getInstance("SHA-1");
        try (InputStream fileInputStream = new FileInputStream(filePath)) {
            byte[] buffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = fileInputStream.read(buffer)) != -1) {
                sha1Digest.update(buffer, 0, bytesRead);
            }
        }
        byte[] sha1Hash = sha1Digest.digest();
        StringBuilder hexString = new StringBuilder();
        for (byte hashByte : sha1Hash) {
            String hex = Integer.toHexString(0xFF & hashByte);
            if (hex.length() == 1) {
                hexString.append('0');
            }
            hexString.append(hex);
        }

        sha1 = hexString.toString();
        return sha1;
    }
    public String getSha1 ()
    {
        return sha1;
    }

    public static byte[] readFile(String inputFile) throws IOException {
        ByteArrayOutputStream bytes = new ByteArrayOutputStream();

        try (FileInputStream files = new FileInputStream(inputFile)) {
            byte[] br = new byte[1024];
            int bytesRead;
            while ((bytesRead = files.read(br)) != -1) {
                bytes.write(br, 0, bytesRead);
            }
        }
        return bytes.toByteArray();
    }

    public static String createBlob(String inputFile) throws IOException, NoSuchAlgorithmException {
        byte[] data = readFile(inputFile);
        String hash = calculateSHA1(new String(data));

        File folder = new File("objects");

        if (!folder.exists()) {
            folder.mkdir();
        }
        String outputFile = "objects" + File.separator + hash;
        Files.write(Paths.get(outputFile), data);
        return hash;
    }
}