由于没有发现潜在的递归导致MySQL链接数溢出：MySQLNonTransientConnectionException: Data source rejected establishment of connection, message from server: "Too many connec

DAOProxy的代码：下面代码中红色高亮的就是出问题的地方，DAOFactory中会构造一个PersonDAOProxy，调用listPersons或者addPerson显然会导致递归，从而导致MySQL链接数溢出！将高亮处的代码修改为：dao.listPersons()、dao.addPerson(person)即可！

public class PersonDAOProxy implements IPersonDAO {

private DatabaseConnection conn = null;
private IPersonDAO dao = null;

public PersonDAOProxy() throws NamingException, SQLException {
conn = DatabaseConnection.newInstance();
dao = new PersonDAOImpl(conn.getConnection());
}

@Override
public List<Person> listPersons() throws SQLException {
List<Person> persons = null;
try {
persons = DAOFactory.getIPersonDAOInstance().listPersons();
} catch (Exception e) {
e.printStackTrace();
} finally {
conn.close();
}
return persons;
}

@Override
public void addPerson(Person person) throws SQLException {
try {
DAOFactory.getIPersonDAOInstance().addPerson(person);
} catch (Exception e) {
e.printStackTrace();
} finally {
conn.close();
}
}

}