Blob - Learn Java by Examples

package org.kodejava.jdbc; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.sql.*; public class BlobReadDemo { private static final String URL = "jdbc:mysql://localhost/kodejava"; private static final String USERNAME = "kodejava"; private static final String PASSWORD = "s3cr*t"; public static void main(String[] args) { try (Connection conn = DriverManager.getConnection(URL, USERNAME, PASSWORD)) { String sql = "SELECT name, image FROM product_image"; PreparedStatement stmt = conn.prepareStatement(sql); ResultSet rs = stmt.executeQuery(); while (rs.next()) { String name = rs.getString("name"); File image = new File(name); try (FileOutputStream fos = new FileOutputStream(image)) { byte[] buffer = new byte[1024]; // Get the binary stream of our BLOB data InputStream is = rs.getBinaryStream("image"); while (is.read(buffer) > 0) { fos.write(buffer); } } catch (IOException e) { e.printStackTrace(); } } } catch (SQLException e) { e.printStackTrace(); } } }

CREATE TABLE `product_image` ( `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT, `product_id` bigint(20) unsigned NOT NULL, `name` varchar(255) NOT NULL, `description` varchar(255) DEFAULT NULL, `image` blob, PRIMARY KEY (`id`), KEY `product_id` (`product_id`), CONSTRAINT `product_image_ibfk_1` FOREIGN KEY (`product_id`) REFERENCES `product` (`id`) ) ENGINE = InnoDB;

Database BLOBs (Binary Large Objects) can be used to store any data, such as images, audio, or video files, for instance. This example shows you how we use JDBC library to store image in our database. To send the binary information to the database, we can call the PreparedStatement.setBinaryStream() method and pass the appropriate input stream and its size.

package org.kodejava.jdbc;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class BlobDemo {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection conn =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {
            conn.setAutoCommit(false);

            String sql = "INSERT INTO product_image " +
                         "(product_id, name, description, image) VALUES (?, ?, ?, ?)";
            String image = "/uml-distilled-3rd-edition.jpg";

            try (PreparedStatement stmt = conn.prepareStatement(sql);
                 InputStream is = BlobDemo.class.getResourceAsStream(image)) {

                stmt.setLong(1, 1L);
                stmt.setString(2, "uml-distilled-3rd-edition.jpg");
                stmt.setString(3, "UML Distilled 3rd Edition");
                stmt.setBinaryStream(4, is);
                stmt.execute();

                conn.commit();
            } catch (Exception e) {
                conn.rollback();
                e.printStackTrace();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

The structure of product_image table.

CREATE TABLE `product_image`
(
    `id`          bigint(20) unsigned NOT NULL AUTO_INCREMENT,
    `product_id`  bigint(20) unsigned NOT NULL,
    `name`        varchar(255)        NOT NULL,
    `description` varchar(255) DEFAULT NULL,
    `image`       blob,
    PRIMARY KEY (`id`),
    KEY `product_id` (`product_id`),
    CONSTRAINT `product_image_ibfk_1` FOREIGN KEY (`product_id`) REFERENCES `product` (`id`)
) ENGINE = InnoDB;

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.4.0</version>
</dependency>

Tag Archives: Blob

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