Question

I use this code to fetch data from database table.

public List<Dashboard> getDashboardList() throws SQLException {

        if (ds == null) {
            throw new SQLException("Can't get data source");
        }

        //get database connection
        Connection con = ds.getConnection();

        if (con == null) {
            throw new SQLException("Can't get database connection");
        }

        PreparedStatement ps = con.prepareStatement(
                "SELECT * from GLOBALSETTINGS");

        //get customer data from database
        ResultSet result = ps.executeQuery();

        List<Dashboard> list = new ArrayList<Dashboard>();

        while (result.next()) {
            Dashboard cust = new Dashboard();

            cust.setUser(result.getString("SessionTTL"));
            cust.setPassword(result.getString("MAXACTIVEUSERS"));


            //store all data into a List
            list.add(cust);
        }

        return list;
    }

This code is a part of a JSF page which is deployed on glassfish server. The problem is that when I reload the JSF page many times(around 8 times) the web page freezes. I suspect that the thread pool is fill and there is no space for new connections. How I can solve the problem? Close the connection when the query is finished or there is another way?

Best wishes

Answer 1

First of all: Yes you should close your connection when your done by explicitly calling the close() method. Closing a connection will release database resources.

UPDATE: And you should close the PreparedStatement as well (with close()). I would also recommend to handle SQLExceptions in your method and not throw it, since you need to make sure that your statement and connection are closed even if an exception occurs.

Something like this:

Connection connection = dataSource.getConnection();
try {
    PreparedStatement statement = connection.prepareStatement();
    try {
        // Work with the statement
    catch (SQLException e ) {
        // Handle exceptions
} catch (SQLException e {
    // Handle exceptions
    } finally {
        statement.close();
    }
} finally {
    connection.close();
}

Furthermore, you should not query the database in a bean field’s getter method. Getters can be called several times during each request. The more elegant way would be to prepare the DashboardList in the constructor or @PostConstruct of your bean.