Oracle - column CLOB Base 64 to file

Extractclob.java

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package extractclob;

import java.io.File;
import java.io.FileWriter;
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import net.iharder.Base64;
/**
 * @author rgomes
 */
public class Extractclob {
    
    static String horas(int a) {
        String formado;
        if (a == 1){
           formado = "HH:mm:ss";
        } else {
           formado = "dd/MM/yyyy HH:mm:ss";       
        }
        DateFormat dateFormat = new SimpleDateFormat(formado);
        Date date = new Date();
        return dateFormat.format(date);
    }
    
    static void extractfiles(){
        try{
            Class.forName("oracle.jdbc.driver.OracleDriver");
            Connection conn = DriverManager.getConnection("jdbc:oracle:thin:apps/apps@10.50.100.70:1611:TEST");
            String sql = "SELECT attach_filename, attach_content_bytes FROM CC_CEM_ATTACHMENTS where attach_filename <> 'Thumbnail' and attach_id in (83,103)";
            PreparedStatement stmt = conn.prepareStatement(sql);
            ResultSet resultSet = stmt.executeQuery();
            
            while (resultSet.next()) {
                String file_name = resultSet.getString(1);
                File data = new File("C:\\kbfiles\\attach\\"+file_name);
                Reader reader = resultSet.getCharacterStream(2);
                FileWriter writer = new FileWriter(data);
                char[] buffer = new char[1];
                String a = null;
                while (reader.read(buffer) > 0) {
                    writer.write(buffer);
                }
                writer.close();
                Base64.decodeFileToFile("C:\\kbfiles\\attach\\"+file_name, "C:\\kbfiles\\attach\\"+file_name);
            }
            conn.close();
        }catch (Exception e) {
            System.err.println("Exception: "+e.getMessage());
            System.err.println();
        }
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        extractfiles();
    }
    
}