Copying BLOB Values to New Rows

This section describes how to copy BLOB values to new rows with getBlob() and setBlob() methods.

The previous test shows that we can not update a Blob object returned from the getBlob() method. But we can use it without any changes with the PreparedStatement.setBlob() method to copy it to a new row. Here is a test program:

/* OracleBlobSetBlobRevised.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.io.*;
import java.sql.*;
public class OracleBlobSetBlobRevised {
  public static void main(String [] args) {
    Connection con = null;
    try {
      oracle.jdbc.pool.OracleDataSource ds
        = new oracle.jdbc.pool.OracleDataSource();
      ds.setDriverType("thin");
      ds.setServerName("localhost");
      ds.setPortNumber(1521);
      ds.setDatabaseName("XE");
      ds.setUser("Herong");
      ds.setPassword("TopSecret");
      con = ds.getConnection();

// Deleting records for re-testing
      Statement sta = con.createStatement();
      sta.executeUpdate(
        "DELETE FROM Image WHERE Subject LIKE 'Copy of %'");

// Creating a PreparedStatement for inserting new records
      PreparedStatement ps = con.prepareStatement(
        "INSERT INTO Image (Subject, Body, ID) VALUES (?,?,?)");

// Looping though the first 3 records
      ResultSet res = sta.executeQuery(
        "SELECT * FROM Image ORDER BY ID");
      int i = 0;
      while (res.next() && i<3) {
        i++;
        System.out.println("Copying record ID: "+res.getInt("ID"));
        String subject = res.getString("Subject");
        Blob body = res.getBlob("Body");

// Oracle does not allow to modify the Blob object
//        byte[] chuck = {(byte)0x00, (byte)0x00, (byte)0x00,
//          (byte)0x00, (byte)0x00, (byte)0x00};
//        body.setBytes(1,chuck);

// Inserting a new record with setBlob()
        ps.setString(1, "Copy of "+subject);
        ps.setBlob(2,body);
        ps.setInt(3,res.getInt("ID")+100);
        ps.executeUpdate();
      }
      ps.close();
      res.close();

// Checking the new records
      res = sta.executeQuery(
        "SELECT * FROM Image WHERE Subject LIKE 'Copy of %'");
      while (res.next()) {
        System.out.println("Record ID: "+res.getInt("ID"));
        System.out.println("   Subject = "+res.getString("Subject"));
        byte[] body = res.getBytes("Body");
        String bodyHex = bytesToHex(body, 32);
        System.out.println("   Body in HEX = "+bodyHex+"...");
      }
      res.close();

      sta.close();
      con.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
  public static String bytesToHex(byte[] bytes, int max) {
    StringBuffer buffer = new StringBuffer();
    for (int i=0; i<bytes.length && i<max; i++) {
      buffer.append(Integer.toHexString(bytes[i] & 0xFF));
    }
    return buffer.toString().toUpperCase();
  }
}

The program worked correctly:

herong> java -cp .;ojdbc11.jar OracleBlobSetBlobRevised

Copying record ID: 1
Copying record ID: 2
Copying record ID: 3
Record ID: 101
   Subject = Copy of Test on INSERT statement
   Body in HEX = C9CBBBCCCEB9C8CABCCCCEB9C9CBBB...
Record ID: 102
   Subject = Copy of Test of the setBytes() method
   Body in HEX = C9CBBBCCCEB9C8CABCCCCEB9C9CBBB...
Record ID: 103
   Subject = Copy of Test of setBinaryStream() methods
   Body in HEX = CAFEBABE000320BAA03D04A704BA0204A804CA0204D8...

Table of Contents

 About This Book

 JDBC (Java Database Connectivity) Introduction

 JDK (Java SE) Installation

 Oracle Express Edition Installation on Windows

 Oracle JDBC Drivers

 Oracle - Reference Implementation of JdbcRowSet

 Oracle - PreparedStatement

 Oracle - JBDC CallableStatement

 Oracle CLOB (Character Large Object) - TEXT

Oracle BLOB (Binary Large Object) - BLOB

 Overview of BLOB (Binary Large Object)

 Create Tables with CLOB Columns

 Inserting BLOB Values with SQL INSERT Statements

 Inserting BLOB Values with setBytes() Method

 Inserting BLOB Values with setBinaryStream() Method

 Closing InputStream Too Early on setBinaryStream()

 Retrieving BLOB Values with getBytes() Method

 Retrieving BLOB Values with getBinaryStream() Method

 Retrieving BLOB Values with getBlob() Method

 Inserting BLOB Values with setBlob() Method

Copying BLOB Values to New Rows

 Archived Tutorials

 References

 Full Version in PDF/EPUB