Storing and Retrieving Images and Files with JDBC

import java.io.InputStream;
import java.io.Reader;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Arrays;
 
public class Lobs {
    public static void main(String[] args) throws Exception {
        // Two small files to store: a fake "photo" and a text document.
        byte[] photoBytes = new byte[2048];
        for (int i = 0; i < photoBytes.length; i++) {
            photoBytes[i] = (byte) (i * 7);
        }
        Path photo = Files.write(Path.of("photo.png"), photoBytes);
        Path essay = Files.writeString(Path.of("essay.txt"),
            "My favorite subject is Java.\nI like collections the most.\n");
 
        try (Connection con =
                 DriverManager.getConnection("jdbc:h2:mem:school")) {
            try (Statement st = con.createStatement()) {
                st.execute("CREATE TABLE document (id INT PRIMARY KEY, "
                    + "student VARCHAR(50), photo BLOB, essay CLOB)");
            }
 
            // Store: stream the files straight into the database.
            String insert = "INSERT INTO document VALUES (?, ?, ?, ?)";
            try (PreparedStatement ps = con.prepareStatement(insert);
                 InputStream in = Files.newInputStream(photo);
                 Reader reader = Files.newBufferedReader(essay)) {
                ps.setInt(1, 1);
                ps.setString(2, "Navika");
                ps.setBinaryStream(3, in, Files.size(photo));
                ps.setCharacterStream(4, reader);
                System.out.println(ps.executeUpdate() + " row stored");
            }
 
            // Retrieve: stream them back out to new files.
            String query = "SELECT photo, essay FROM document WHERE id = ?";
            try (PreparedStatement ps = con.prepareStatement(query)) {
                ps.setInt(1, 1);
                try (ResultSet rs = ps.executeQuery()) {
                    rs.next();
                    Path photoCopy = Path.of("photo-copy.png");
                    try (InputStream in = rs.getBinaryStream("photo")) {
                        Files.copy(in, photoCopy);
                    }
                    String text = rs.getString("essay");
                    System.out.println("Photo bytes back: "
                        + Files.size(photoCopy));
                    System.out.println("Identical to the original? "
                        + Arrays.equals(photoBytes,
                            Files.readAllBytes(photoCopy)));
                    System.out.println("Essay characters: " + text.length());
                    System.out.println("First line: "
                        + text.lines().findFirst().orElse(""));
                    Files.delete(photoCopy);
                }
            }
        } finally {
            Files.delete(photo);
            Files.delete(essay);
        }
    }
}