Retrieving BLOB Values with getBytes() Method

This section describes how to retrieve BLOB values with the ResultSet.getBytes() method.

The simplest way to retrieve the character string value from a BLOB column is to use the getBytes() method on the ResultSet object. Here is short example program:

/* SqlServerBlobGetBytes.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.io.*;
import java.sql.*;
public class SqlServerBlobGetBytes {
  public static void main(String [] args) {
    Connection con = null;
    try {
      com.microsoft.sqlserver.jdbc.SQLServerDataSource ds
        = new com.microsoft.sqlserver.jdbc.SQLServerDataSource();
      ds.setServerName("localhost");
//      ds.setPortNumber(60782);
      ds.setInstanceName("SQLEXPRESS");
      ds.setDatabaseName("AdventureWorks2019");
      ds.setUser("Herong");
      ds.setPassword("T0pSecret");
      con = ds.getConnection();

// Retrieving BLOB value with getBytes()
      Statement sta = con.createStatement();
      ResultSet res = sta.executeQuery("SELECT * FROM Image");
      int i = 0;
      while (res.next() && i<3) {
        i++;
        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();
  }
}

bytesToHex() method is used to convert a byte array to a Hex string. The output of the program confirms that CLOB values can be retrieved with getBytes() method on the ResultSet object:

herong> java -cp .;mssql-jdbc-9.4.1.jre16.jar SqlServerBlobGetBytes

Record ID: 1
   Subject = Test on INSERT statement
   Body in HEX = C9CBBBCCCEB9C8CABCCCCEB9C9CBBB...
Record ID: 2
   Subject = Test of the setBytes() method
   Body in HEX = C9CBBBCCCEB9C8CABCCCCEB9C9CBBB...
Record ID: 4
   Subject = Test of setBinaryStream() methods
   Body in HEX = CAFEBABE000320B5A03B0487049A02048804AA0204BA...

Table of Contents

 About This Book

 JDBC (Java Database Connectivity) Introduction

 JDK (Java SE) Installation

 Microsoft SQL Server Express Edition

 Microsoft JDBC Driver for SQL Server

 Microsoft JDBC Driver - Query Statements and Result Sets

 Microsoft JDBC Driver - DatabaseMetaData Object

 Microsoft JDBC Driver - DDL Statements

 Microsoft JDBC Driver - DML Statements

 SQL Server - PreparedStatement

 SQL Server CLOB (Character Large Object) - TEXT

SQL Server 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

 JDBC-ODBC Bridge Driver - sun.jdbc.odbc.JdbcOdbcDriver

 JDBC-ODBC Bridge Driver - Flat Text Files

 JDBC-ODBC Bridge Driver - MS Access

 JDBC-ODBC Bridge Driver - MS SQL Server

 Archived Tutorials

 References

 Full Version in PDF/EPUB