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package oracle.toplink.essentials.sessions;

import java.util.*;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.sql.*;
import oracle.toplink.essentials.exceptions.*;
import oracle.toplink.essentials.internal.security.PrivilegedAccessHelper;
import oracle.toplink.essentials.internal.security.PrivilegedNewInstanceFromClass;

/**
 * <p>
 * <b>Purpose</b>:Use this Connector to build a java.sql.Connection by
 * directly instantiating the Driver, as opposed to using the DriverManager.
 *
 * @author Big Country
 * @since TOPLink/Java 2.1
 */
public class DirectConnector extends DefaultConnector {

    /** cache up the instantiated Driver to speed up reconnects */
    protected Driver cachedInstance;

    /**
     * PUBLIC:
     * Construct a Connector with default settings (Sun JDBC-ODBC bridge).
     * Although this does not really make sense for a "direct" Connector -
     * the Sun JdbcOdbcDriver works fine with the DriverManager.
     */
    public DirectConnector() {
        super();
    }

    /**
     * PUBLIC:
     * Construct a Connector with the specified settings.
     */
    public DirectConnector(String driverClassName, String driverURLHeader, String databaseURL) {
        super(driverClassName, driverURLHeader, databaseURL);
    }

    /**
     * INTERNAL:
     * Connect with the specified properties and return the Connection.
     * @return java.sql.Connection
     */
    public Connection connect(Properties properties) throws DatabaseException {
        try {
            return this.instantiateDriver(this.loadDriver()).connect(this.getConnectionString(), properties);
        } catch (SQLException exception) {
            throw DatabaseException.sqlException(exception);
        }
    }

    /**
     * INTERNAL:
     * Instantiate the Driver if necessary.
     * @return java.sql.Driver
     */
    protected Driver instantiateDriver(Class driverClass) throws DatabaseException {
        if (cachedInstance != null) {
            return cachedInstance;
        }

        try {
            if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()){
                try {
                    cachedInstance = (Driver)AccessController.doPrivileged(new PrivilegedNewInstanceFromClass(driverClass));
                } catch (PrivilegedActionException exception) {
                    Exception throwableException = exception.getException();
                    if (throwableException instanceof InstantiationException) {
                        throw DatabaseException.configurationErrorNewInstanceInstantiationException((InstantiationException)throwableException, driverClass);
                    } else {
                        throw DatabaseException.configurationErrorNewInstanceIllegalAccessException((IllegalAccessException)throwableException, driverClass);
                    }
                }
            } else {
                cachedInstance = (Driver)PrivilegedAccessHelper.newInstanceFromClass(driverClass);
            }
            return cachedInstance;
        } catch (InstantiationException ie) {
            throw DatabaseException.configurationErrorNewInstanceInstantiationException(ie, driverClass);
        } catch (IllegalAccessException iae) {
            throw DatabaseException.configurationErrorNewInstanceIllegalAccessException(iae, driverClass);
        }
    }
}