Perturbando o Povo com Modelagem!

package br.com.trimbase.rastreio.bd;

import java.sql.*;

public class DAO {

	// Pretendo fazer desse DAO algo generico (para qq banco), por isso estes atributos
	private ConnectionPool pool = null;
	private Connection con = null;
	private String host = null;
	private String usuario = null;
	private String senha = null;
	private String URL = null;
	private String driver = null;
	private String baseDados = null;
	private String prefixoBase = null;
	private String porta = null;
	
	public DAO() {
		super();
		host        = "localhost";
		usuario     = "postgres";
		senha       = "agente86";
		driver      = "org.postgresql.Driver";
		baseDados   = "os";
		prefixoBase = "jdbc:postgresql://";
		porta       = "5432";

		URL = prefixoBase + host + ":" + porta + "/" + baseDados + "/";
	}

	public synchronized Connection getConnection() {
		pool = ConnectionPool.getInstance(URL, usuario, senha, driver, 5);
		con = pool.getConnection();
		return con;
	}
	
	public synchronized void liberaConexao(Connection con) {
		if (pool != null) {
			pool.returnConnection(con);
		}
	}
	
	public void terminaConexoes() {
		if (pool != null) {
			pool.release();			
		}
		pool = null;
	}

	public ConnectionPool getPool() {
		return pool;
	}

	public void setPool(ConnectionPool pool) {
		this.pool = pool;
	}
}

package br.com.trimbase.rastreio.bd;

import java.sql.PreparedStatement;
import java.sql.Connection;
import java.sql.ResultSet;

public abstract class DAOGenerico {
	private DAO dao = new DAO();
	private Connection conn = dao.getConnection();

	public long getCodigo(String sequencia) {
		long retorno = 0;
		PreparedStatement stmt;
		String sql;
		try {
			sql  = " SELECT nextval(\'" + sequencia + "\') ";
			stmt = getConn().prepareStatement(sql);
			ResultSet rs = stmt.executeQuery();
			while ((rs != null) && (rs.next())) {
				retorno = rs.getLong(1);
			}
		}catch(Exception e) {
			e.printStackTrace();
		}
		
		dao.liberaConexao(conn);

		sql  = null;
		stmt = null;
		dao  = null;
		conn = null;
		
		return retorno;
	}
	
	public Connection getConn() {
		return conn;
	}
	
	public void setConn(Connection conn) {
		this.conn = conn;
	}

	public DAO getDao() {
		return dao;
	}

	public void setDao(DAO dao) {
		this.dao = dao;
	}
}

package br.com.trimbase.agente.dao;

import java.sql.PreparedStatement;
import br.com.trimbase.rastreio.bd.DAOGenerico;
import br.com.trimbase.agente.*;

public class FisicaDAO extends DAOGenerico {
	
	public boolean cadastra(Fisica fisica) {
		boolean retorno = false;
		PreparedStatement stmt;
		long codAgente = getCodigo("agente_agecod_seq");
		
		String sql = " INSERT INTO agente (agecod, agenom, ageobs) VALUES (?, ?, ?) "; 

		try{
			stmt = getConn().prepareStatement(sql);
			stmt.setLong(1, codAgente);
			stmt.setString(2, fisica.getNome());
			stmt.setString(3, fisica.getObs());
			retorno = stmt.execute();
			
			if (retorno) {
				sql = " INSERT INTO fisica (fisage, fiscpf) VALUE (?, ?) ";
				stmt = getConn().prepareStatement(sql);
				stmt.setLong(1, codAgente);
				stmt.setString(2, fisica.getCpf());
				retorno = stmt.execute();
			}
		}catch (Exception ex) {
			ex.printStackTrace();
		}
		
		getDao().liberaConexao(getConn());

		sql  = null;
		stmt = null;
		setDao(null);
		setConn(null);

		return retorno;
	}
}