Dificuldades com inserção de registro na base

package servlet;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.Iterator;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class UploadServlet extends javax.servlet.http.HttpServlet {

    static final long serialVersionUID = 1L;
    static Connection conn;
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doExecute(request, response);
    }

    public static void initConnection() throws Exception {
        String DRIVER = "oracle.jdbc.driver.OracleDriver";
        String URL = "jdbc:oracle:thin:@localhost:1521:xe";
        String USER = "puudia";
        String PASSWORD = new String("puudia");
        
        Class.forName(DRIVER);
        conn = DriverManager.getConnection(URL, USER, PASSWORD);
        
    }
    
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doExecute(request, response);
    }   
    protected void doExecute(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        
        // isso aqui tem que pegar o usuario logado, caso contrario -1 anonymous
        int idusu = 1;
        
        try {
            
            initConnection();
            
            boolean isMultipart = ServletFileUpload.isMultipartContent(request);
            
            // Create a factory for disk-based file items
            FileItemFactory factory = new DiskFileItemFactory();

            // Create a new file upload handler
            ServletFileUpload upload = new ServletFileUpload(factory);

            // Parse the request
            List items = upload.parseRequest(request);
            int i = 0;
            // Process the uploaded items
            Iterator iter = items.iterator();
            while (iter.hasNext()) {
                FileItem item = (FileItem) iter.next();

                // somente se o cmapo do
                if (item.isFormField() == false) {
                    int id = 0;
                    // pegar o id da foto
                    Statement stmt = conn.createStatement();
                    ResultSet rs = stmt.executeQuery("select sfot_id.nextval xxx from dual");
                    if (rs.next()) {
                        id = rs.getInt("xxx");
                    }
                    rs.close();
                    rs = null;
                    stmt.close();
                    stmt = null;
                    
                    String fileName = item.getName();
                    String ext = fileName.substring(fileName.lastIndexOf("."), fileName.length());
                    String file = "D:\\Projetos\\puudia\\web\\fotos\\f"+id+ext;
                    String url = "f"+id+ext;
                    InputStream is = item.getInputStream();
                    FileOutputStream fos = new FileOutputStream(new File(file));                    
                    
                    // gravar foto
                    byte[] b = new byte[1024];
                    while (is.read(b) != -1) {
                        fos.write(b);
                    }
                    fos.flush();
                    fos.close();
                    fos = null;
                    
                    is.close();
                    is = null;
                    
                    PreparedStatement ps = conn.prepareStatement("insert into puudia.foto(fot_id, usu_id, fot_url, fot_descricao, fot_data) values(?, ?, ?, ?, sysdate)");

                    ps.setInt(1, id);
                    ps.setInt(2, idusu);
                    ps.setString(3, url);
                    ps.setString(4, "foto sem comentário");

                    ps.executeUpdate();

                    ps.close();
                    ps = null;

                }
            }