How to convert BLOB to Byte Array in java?

You can contents of a blob into a byte array using the getBytes() method.

Example

import java.awt.Image;
import java.awt.image.BufferedImage;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Arrays;
public class BlobToByteArray {
   public static void main(String[] args) throws Exception {
      Image image = new BufferedImage(300,400, BufferedImage.TYPE_INT_RGB);
      String JDBC_DRIVER = "com.mysql.jdbc.Driver";
      String DB_URL = "jdbc:mysql://localhost/mydb";
      String USER = "root";
      String PASS = "password";
      Connection conn = null;
      Statement stmt = null;
      Class.forName("com.mysql.jdbc.Driver");
      System.out.println("Connecting to a selected database...");
      conn = DriverManager.getConnection(DB_URL, USER, PASS);
      System.out.println("Connected database successfully...");
      System.out.println("getting blob.......");
      stmt = conn.createStatement();
      String sql = "SELECT * FROM sample";
      ResultSet rs = stmt.executeQuery(sql);
      while(rs.next()) {
         Blob blob = rs.getBlob("image");
         byte [] bytes = blob.getBytes(1l, (int)blob.length());
         for(int i=0; i<bytes.length;i++) {
            System.out.println(Arrays.toString(bytes));
         }
      }
   }
}

Output

Connecting to a selected database...
Connected database successfully...
getting blob.......
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]
[100, 58, 115, 97, 109, 112, 108, 101, 46, 106, 112, 103]