Conta.java
package br.com.caelum.financas.modelo;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class Conta {
    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    private String titular;
    private String numero;
    private String banco;
    private String agencia;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getTitular() {
        return titular;
    }
    public void setTitular(String titular) {
        this.titular = titular;
    }
    public String getNumero() {
        return numero;
    }
    public void setNumero(String numero) {
        this.numero = numero;
    }
    public String getBanco() {
        return banco;
    }
    public void setBanco(String banco) {
        this.banco = banco;
    }
    public String getAgencia() {
        return agencia;
    }
    public void setAgencia(String agencia) {
        this.agencia = agencia;
    }
}
TsteJPA.java
package br.com.caelum.financas.teste;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import br.com.caelum.financas.modelo.Conta;
public class TesteJPA {
    public static void main(String[] args) {
        Conta conta = new Conta();
        conta.setTitular("joao fernando");
        conta.setBanco("brasil");
        conta.setNumero("123456");
        conta.setAgencia("321");
        EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("financas");
        EntityManager manager = entityManagerFactory.createEntityManager();
        manager.getTransaction().begin();
        manager.persist(conta);
        manager.getTransaction().commit();
        manager.close();
    }
}
persistence.xml
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
        http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
    version="2.0">
    <!-- unidade de persistencia com o nome financas -->
    <persistence-unit name="financas">
        <!-- Implementação do JPA, no nosso caso Hibernate -->
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <!-- Aqui são listadas todas as entidades -->
        <class>br.com.caelum.financas.modelo.Conta</class>
        <properties>
            <!-- Propriedades JDBC -->
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost/financas" />
            <property name="javax.persistence.jdbc.user" value="root" />
            <property name="javax.persistence.jdbc.password" value="" />
            <!-- Configurações específicas do Hibernate -->
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect" />
            <property name="hibernate.hbm2ddl.auto" value="update" />
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.format_sql" value="true" />
        </properties>
    </persistence-unit>
</persistence>