https://openjdk.java.net/ 
/*
 * Copyright (c) 1996, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.sql;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.ServiceLoader;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.stream.Stream;

import jdk.internal.reflect.CallerSensitive;
import jdk.internal.reflect.Reflection;



The basic service for managing a set of JDBC drivers.


NOTE: The DataSource interface, provides another way to connect to a data source. The use of a DataSource object is the preferred means of connecting to a data source. 
 As part of its initialization, the DriverManager class will attempt to load available JDBC drivers by using: 
    

  • The jdbc.drivers system property which contains a colon separated list of fully qualified class names of JDBC drivers. Each driver is loaded using the 
system class loader: 
      

    • jdbc.drivers=foo.bah.Driver:wombat.sql.Driver:bad.taste.ourDriver 
    

  • Service providers of the java.sql.Driver class, that are loaded via the service-provider loading mechanism. 


See Also:
Implementation Note: DriverManager initialization is done lazily and looks up service providers using the thread context class loader. The drivers loaded and available to an application will depend on the thread context class loader of the thread that triggers driver initialization by DriverManager. 
When the method getConnection is called, the DriverManager will attempt to locate a suitable driver from amongst those loaded at initialization and those loaded explicitly using the same class loader as the current application.
Since:1.1
/**
 * The basic service for managing a set of JDBC drivers.
 * <p>
 * <strong>NOTE:</strong> The {@link javax.sql.DataSource} interface, provides
 * another way to connect to a data source.
 * The use of a {@code DataSource} object is the preferred means of
 * connecting to a data source.
 * <P>
 * As part of its initialization, the {@code DriverManager} class will
 * attempt to load available JDBC drivers by using:
 * <ul>
 * <li>The {@code jdbc.drivers} system property which contains a
 * colon separated list of fully qualified class names of JDBC drivers. Each
 * driver is loaded using the {@linkplain ClassLoader#getSystemClassLoader
 * system class loader}:
 * <ul>
 * <li>{@code jdbc.drivers=foo.bah.Driver:wombat.sql.Driver:bad.taste.ourDriver}
 * </ul>
 *
 * <li>Service providers of the {@code java.sql.Driver} class, that are loaded
 * via the {@linkplain ServiceLoader#load service-provider loading} mechanism.
 *</ul>
 *
 * @implNote
 * {@code DriverManager} initialization is done lazily and looks up service
 * providers using the thread context class loader.  The drivers loaded and
 * available to an application will depend on the thread context class loader of
 * the thread that triggers driver initialization by {@code DriverManager}.
 *
 * <P>When the method {@code getConnection} is called,
 * the {@code DriverManager} will attempt to
 * locate a suitable driver from amongst those loaded at
 * initialization and those loaded explicitly using the same class loader
 * as the current application.
 *
 * @see Driver
 * @see Connection
 * @since 1.1
 */
public class DriverManager {


    // List of registered JDBC drivers
    private final static CopyOnWriteArrayList<DriverInfo> registeredDrivers = new CopyOnWriteArrayList<>();
    private static volatile int loginTimeout = 0;
    private static volatile java.io.PrintWriter logWriter = null;
    private static volatile java.io.PrintStream logStream = null;
    // Used in println() to synchronize logWriter
    private final static Object logSync = new Object();
    // Used in ensureDriversInitialized() to synchronize driversInitialized
    private final static Object lockForInitDrivers = new Object();
    private static volatile boolean driversInitialized;
    private static final String JDBC_DRIVERS_PROPERTY = "jdbc.drivers";

    /* Prevent the DriverManager class from being instantiated. */
    private DriverManager(){}

    
The SQLPermission constant that allows the
setting of the logging stream.

Since:1.3
/**
     * The <code>SQLPermission</code> constant that allows the
     * setting of the logging stream.
     * @since 1.3
     */
    final static SQLPermission SET_LOG_PERMISSION =
        new SQLPermission("setLog");

    
The SQLPermission constant that allows the un-register a registered JDBC driver. 
Since:1.8
/**
     * The {@code SQLPermission} constant that allows the
     * un-register a registered JDBC driver.
     * @since 1.8
     */
    final static SQLPermission DEREGISTER_DRIVER_PERMISSION =
        new SQLPermission("deregisterDriver");

    //--------------------------JDBC 2.0-----------------------------

    
Retrieves the log writer.
The getLogWriter and setLogWriter
methods should be used instead
of the get/setlogStream methods, which are deprecated.

See Also:
Returns:a java.io.PrintWriter object
Since:1.2
/**
     * Retrieves the log writer.
     *
     * The <code>getLogWriter</code> and <code>setLogWriter</code>
     * methods should be used instead
     * of the <code>get/setlogStream</code> methods, which are deprecated.
     * @return a <code>java.io.PrintWriter</code> object
     * @see #setLogWriter
     * @since 1.2
     */
    public static java.io.PrintWriter getLogWriter() {
            return logWriter;
    }

    
Sets the logging/tracing PrintWriter object
that is used by the DriverManager and all drivers.

 If a security manager exists, its checkPermission method is first called with a SQLPermission("setLog") permission to check that the caller is allowed to call setLogWriter. 
Params:
  • out – the new logging/tracing PrintStream object;
     null to disable logging and tracing
Throws:
  • SecurityException – if a security manager exists and its checkPermission method denies permission to set the log writer.
See Also:
Since:1.2
/**
     * Sets the logging/tracing <code>PrintWriter</code> object
     * that is used by the <code>DriverManager</code> and all drivers.
     *<P>
     * If a security manager exists, its {@code checkPermission}
     * method is first called with a {@code SQLPermission("setLog")}
     * permission to check that the caller is allowed to call {@code setLogWriter}.
     *
     * @param out the new logging/tracing <code>PrintStream</code> object;
     *      <code>null</code> to disable logging and tracing
     * @throws SecurityException if a security manager exists and its
     * {@code checkPermission} method denies permission to set the log writer.
     * @see SecurityManager#checkPermission
     * @see #getLogWriter
     * @since 1.2
     */
    public static void setLogWriter(java.io.PrintWriter out) {

        SecurityManager sec = System.getSecurityManager();
        if (sec != null) {
            sec.checkPermission(SET_LOG_PERMISSION);
        }
            logStream = null;
            logWriter = out;
    }


    //---------------------------------------------------------------

    
Attempts to establish a connection to the given database URL.
The DriverManager attempts to select an appropriate driver from
the set of registered JDBC drivers.


Note: If a property is specified as part of the url and is also specified in the Properties object, it is implementation-defined as to which value will take precedence. For maximum portability, an application should only specify a property once. 
Params:
  • url – a database url of the form
 jdbc:subprotocol:subname
  • info – a list of arbitrary string tag/value pairs as
connection arguments; normally at least a "user" and
"password" property should be included
Throws:
  • SQLException – if a database access error occurs or the url is null
  • SQLTimeoutException –  when the driver has determined that the timeout value specified by the setLoginTimeout method has been exceeded and has at least tried to cancel the current database connection attempt
Returns:a Connection to the URL
/**
     * Attempts to establish a connection to the given database URL.
     * The <code>DriverManager</code> attempts to select an appropriate driver from
     * the set of registered JDBC drivers.
     *<p>
     * <B>Note:</B> If a property is specified as part of the {@code url} and
     * is also specified in the {@code Properties} object, it is
     * implementation-defined as to which value will take precedence.
     * For maximum portability, an application should only specify a
     * property once.
     *
     * @param url a database url of the form
     * <code> jdbc:<em>subprotocol</em>:<em>subname</em></code>
     * @param info a list of arbitrary string tag/value pairs as
     * connection arguments; normally at least a "user" and
     * "password" property should be included
     * @return a Connection to the URL
     * @exception SQLException if a database access error occurs or the url is
     * {@code null}
     * @throws SQLTimeoutException  when the driver has determined that the
     * timeout value specified by the {@code setLoginTimeout} method
     * has been exceeded and has at least tried to cancel the
     * current database connection attempt
     */
    @CallerSensitive
    public static Connection getConnection(String url,
        java.util.Properties info) throws SQLException {

        return (getConnection(url, info, Reflection.getCallerClass()));
    }

    
Attempts to establish a connection to the given database URL.
The DriverManager attempts to select an appropriate driver from
the set of registered JDBC drivers.


Note: If the user or password property are also specified as part of the url, it is implementation-defined as to which value will take precedence. For maximum portability, an application should only specify a property once. 
Params:
  • url – a database url of the form
jdbc:subprotocol:subname
  • user – the database user on whose behalf the connection is being
  made
  • password – the user's password
Throws:
  • SQLException – if a database access error occurs or the url is null
  • SQLTimeoutException –  when the driver has determined that the timeout value specified by the setLoginTimeout method has been exceeded and has at least tried to cancel the current database connection attempt
Returns:a connection to the URL
/**
     * Attempts to establish a connection to the given database URL.
     * The <code>DriverManager</code> attempts to select an appropriate driver from
     * the set of registered JDBC drivers.
     *<p>
     * <B>Note:</B> If the {@code user} or {@code password} property are
     * also specified as part of the {@code url}, it is
     * implementation-defined as to which value will take precedence.
     * For maximum portability, an application should only specify a
     * property once.
     *
     * @param url a database url of the form
     * <code>jdbc:<em>subprotocol</em>:<em>subname</em></code>
     * @param user the database user on whose behalf the connection is being
     *   made
     * @param password the user's password
     * @return a connection to the URL
     * @exception SQLException if a database access error occurs or the url is
     * {@code null}
     * @throws SQLTimeoutException  when the driver has determined that the
     * timeout value specified by the {@code setLoginTimeout} method
     * has been exceeded and has at least tried to cancel the
     * current database connection attempt
     */
    @CallerSensitive
    public static Connection getConnection(String url,
        String user, String password) throws SQLException {
        java.util.Properties info = new java.util.Properties();

        if (user != null) {
            info.put("user", user);
        }
        if (password != null) {
            info.put("password", password);
        }

        return (getConnection(url, info, Reflection.getCallerClass()));
    }

    
Attempts to establish a connection to the given database URL.
The DriverManager attempts to select an appropriate driver from
the set of registered JDBC drivers.

Params:
  • url – a database url of the form
  jdbc:subprotocol:subname
Throws:
  • SQLException – if a database access error occurs or the url is null
  • SQLTimeoutException –  when the driver has determined that the timeout value specified by the setLoginTimeout method has been exceeded and has at least tried to cancel the current database connection attempt
Returns:a connection to the URL
/**
     * Attempts to establish a connection to the given database URL.
     * The <code>DriverManager</code> attempts to select an appropriate driver from
     * the set of registered JDBC drivers.
     *
     * @param url a database url of the form
     *  <code> jdbc:<em>subprotocol</em>:<em>subname</em></code>
     * @return a connection to the URL
     * @exception SQLException if a database access error occurs or the url is
     * {@code null}
     * @throws SQLTimeoutException  when the driver has determined that the
     * timeout value specified by the {@code setLoginTimeout} method
     * has been exceeded and has at least tried to cancel the
     * current database connection attempt
     */
    @CallerSensitive
    public static Connection getConnection(String url)
        throws SQLException {

        java.util.Properties info = new java.util.Properties();
        return (getConnection(url, info, Reflection.getCallerClass()));
    }

    
Attempts to locate a driver that understands the given URL.
The DriverManager attempts to select an appropriate driver from
the set of registered JDBC drivers.

Params:
  • url – a database URL of the form
    jdbc:subprotocol:subname
Throws:
Returns:a Driver object representing a driver
that can connect to the given URL
/**
     * Attempts to locate a driver that understands the given URL.
     * The <code>DriverManager</code> attempts to select an appropriate driver from
     * the set of registered JDBC drivers.
     *
     * @param url a database URL of the form
     *     <code>jdbc:<em>subprotocol</em>:<em>subname</em></code>
     * @return a <code>Driver</code> object representing a driver
     * that can connect to the given URL
     * @exception SQLException if a database access error occurs
     */
    @CallerSensitive
    public static Driver getDriver(String url)
        throws SQLException {

        println("DriverManager.getDriver(\"" + url + "\")");

        ensureDriversInitialized();

        Class<?> callerClass = Reflection.getCallerClass();

        // Walk through the loaded registeredDrivers attempting to locate someone
        // who understands the given URL.
        for (DriverInfo aDriver : registeredDrivers) {
            // If the caller does not have permission to load the driver then
            // skip it.
            if (isDriverAllowed(aDriver.driver, callerClass)) {
                try {
                    if (aDriver.driver.acceptsURL(url)) {
                        // Success!
                        println("getDriver returning " + aDriver.driver.getClass().getName());
                    return (aDriver.driver);
                    }

                } catch(SQLException sqe) {
                    // Drop through and try the next driver.
                }
            } else {
                println("    skipping: " + aDriver.driver.getClass().getName());
            }

        }

        println("getDriver: no suitable driver");
        throw new SQLException("No suitable driver", "08001");
    }


    
Registers the given driver with the DriverManager. A newly-loaded driver class should call the method registerDriver to make itself known to the DriverManager. If the driver is currently registered, no action is taken. 
Params:
  • driver – the new JDBC Driver that is to be registered with the DriverManager
Throws:
/**
     * Registers the given driver with the {@code DriverManager}.
     * A newly-loaded driver class should call
     * the method {@code registerDriver} to make itself
     * known to the {@code DriverManager}. If the driver is currently
     * registered, no action is taken.
     *
     * @param driver the new JDBC Driver that is to be registered with the
     *               {@code DriverManager}
     * @exception SQLException if a database access error occurs
     * @exception NullPointerException if {@code driver} is null
     */
    public static void registerDriver(java.sql.Driver driver)
        throws SQLException {

        registerDriver(driver, null);
    }

    
Registers the given driver with the DriverManager. A newly-loaded driver class should call the method registerDriver to make itself known to the DriverManager. If the driver is currently registered, no action is taken. 
Params:
  • driver – the new JDBC Driver that is to be registered with the DriverManager
  • da –  the DriverAction implementation to be used when DriverManager#deregisterDriver is called
Throws:
Since:1.8
/**
     * Registers the given driver with the {@code DriverManager}.
     * A newly-loaded driver class should call
     * the method {@code registerDriver} to make itself
     * known to the {@code DriverManager}. If the driver is currently
     * registered, no action is taken.
     *
     * @param driver the new JDBC Driver that is to be registered with the
     *               {@code DriverManager}
     * @param da     the {@code DriverAction} implementation to be used when
     *               {@code DriverManager#deregisterDriver} is called
     * @exception SQLException if a database access error occurs
     * @exception NullPointerException if {@code driver} is null
     * @since 1.8
     */
    public static void registerDriver(java.sql.Driver driver,
            DriverAction da)
        throws SQLException {

        /* Register the driver if it has not already been added to our list */
        if (driver != null) {
            registeredDrivers.addIfAbsent(new DriverInfo(driver, da));
        } else {
            // This is for compatibility with the original DriverManager
            throw new NullPointerException();
        }

        println("registerDriver: " + driver);

    }

    
Removes the specified driver from the DriverManager's list of registered drivers. 
 If a null value is specified for the driver to be removed, then no action is taken. 
 If a security manager exists, its checkPermission method is first called with a SQLPermission("deregisterDriver") permission to check that the caller is allowed to deregister a JDBC Driver. 

If the specified driver is not found in the list of registered drivers,
then no action is taken.  If the driver was found, it will be removed
from the list of registered drivers.

 If a DriverAction instance was specified when the JDBC driver was registered, its deregister method will be called prior to the driver being removed from the list of registered drivers. 
Params:
  • driver – the JDBC Driver to remove
Throws:
  • SQLException – if a database access error occurs
  • SecurityException – if a security manager exists and its checkPermission method denies permission to deregister a driver.
See Also:
/**
     * Removes the specified driver from the {@code DriverManager}'s list of
     * registered drivers.
     * <p>
     * If a {@code null} value is specified for the driver to be removed, then no
     * action is taken.
     * <p>
     * If a security manager exists, its {@code checkPermission}
     * method is first called with a {@code SQLPermission("deregisterDriver")}
     * permission to check that the caller is allowed to deregister a JDBC Driver.
     * <p>
     * If the specified driver is not found in the list of registered drivers,
     * then no action is taken.  If the driver was found, it will be removed
     * from the list of registered drivers.
     * <p>
     * If a {@code DriverAction} instance was specified when the JDBC driver was
     * registered, its deregister method will be called
     * prior to the driver being removed from the list of registered drivers.
     *
     * @param driver the JDBC Driver to remove
     * @exception SQLException if a database access error occurs
     * @throws SecurityException if a security manager exists and its
     * {@code checkPermission} method denies permission to deregister a driver.
     *
     * @see SecurityManager#checkPermission
     */
    @CallerSensitive
    public static void deregisterDriver(Driver driver) throws SQLException {
        if (driver == null) {
            return;
        }

        SecurityManager sec = System.getSecurityManager();
        if (sec != null) {
            sec.checkPermission(DEREGISTER_DRIVER_PERMISSION);
        }

        println("DriverManager.deregisterDriver: " + driver);

        DriverInfo aDriver = new DriverInfo(driver, null);
        synchronized (lockForInitDrivers) {
            if (registeredDrivers.contains(aDriver)) {
                if (isDriverAllowed(driver, Reflection.getCallerClass())) {
                    DriverInfo di = registeredDrivers.get(registeredDrivers.indexOf(aDriver));
                     // If a DriverAction was specified, Call it to notify the
                     // driver that it has been deregistered
                     if (di.action() != null) {
                         di.action().deregister();
                     }
                     registeredDrivers.remove(aDriver);
                } else {
                    // If the caller does not have permission to load the driver then
                    // throw a SecurityException.
                    throw new SecurityException();
                }
            } else {
                println("    couldn't find driver to unload");
            }
        }
    }

    
Retrieves an Enumeration with all of the currently loaded JDBC drivers
to which the current caller has access.

Note: The classname of a driver can be found using
d.getClass().getName()

See Also:
Returns:the list of JDBC Drivers loaded by the caller's class loader
/**
     * Retrieves an Enumeration with all of the currently loaded JDBC drivers
     * to which the current caller has access.
     *
     * <P><B>Note:</B> The classname of a driver can be found using
     * <CODE>d.getClass().getName()</CODE>
     *
     * @return the list of JDBC Drivers loaded by the caller's class loader
     * @see #drivers()
     */
    @CallerSensitive
    public static Enumeration<Driver> getDrivers() {
        ensureDriversInitialized();

        return Collections.enumeration(getDrivers(Reflection.getCallerClass()));
    }

    
Retrieves a Stream with all of the currently loaded JDBC drivers
to which the current caller has access.

Returns:the stream of JDBC Drivers loaded by the caller's class loader
Since:9
/**
     * Retrieves a Stream with all of the currently loaded JDBC drivers
     * to which the current caller has access.
     *
     * @return the stream of JDBC Drivers loaded by the caller's class loader
     * @since 9
     */
    @CallerSensitive
    public static Stream<Driver> drivers() {
        ensureDriversInitialized();

        return getDrivers(Reflection.getCallerClass()).stream();
    }

    private static List<Driver> getDrivers(Class<?> callerClass) {
        List<Driver> result = new ArrayList<>();
        // Walk through the loaded registeredDrivers.
        for (DriverInfo aDriver : registeredDrivers) {
            // If the caller does not have permission to load the driver then
            // skip it.
            if (isDriverAllowed(aDriver.driver, callerClass)) {
                result.add(aDriver.driver);
            } else {
                println("    skipping: " + aDriver.getClass().getName());
            }
        }
        return result;
    }

    
Sets the maximum time in seconds that a driver will wait
while attempting to connect to a database once the driver has
been identified.

Params:
  • seconds – the login time limit in seconds; zero means there is no limit
See Also:
/**
     * Sets the maximum time in seconds that a driver will wait
     * while attempting to connect to a database once the driver has
     * been identified.
     *
     * @param seconds the login time limit in seconds; zero means there is no limit
     * @see #getLoginTimeout
     */
    public static void setLoginTimeout(int seconds) {
        loginTimeout = seconds;
    }

    
Gets the maximum time in seconds that a driver can wait
when attempting to log in to a database.

See Also:
Returns:the driver login time limit in seconds
/**
     * Gets the maximum time in seconds that a driver can wait
     * when attempting to log in to a database.
     *
     * @return the driver login time limit in seconds
     * @see #setLoginTimeout
     */
    public static int getLoginTimeout() {
        return (loginTimeout);
    }

    
Sets the logging/tracing PrintStream that is used
by the DriverManager
and all drivers.

 If a security manager exists, its checkPermission method is first called with a SQLPermission("setLog") permission to check that the caller is allowed to call setLogStream. 
Params:
  • out – the new logging/tracing PrintStream; to disable, set to null
Throws:
  • SecurityException – if a security manager exists and its checkPermission method denies permission to set the log stream.
See Also:
Deprecated:Use setLogWriter
/**
     * Sets the logging/tracing PrintStream that is used
     * by the <code>DriverManager</code>
     * and all drivers.
     *<P>
     * If a security manager exists, its {@code checkPermission}
     * method is first called with a {@code SQLPermission("setLog")}
     * permission to check that the caller is allowed to call {@code setLogStream}.
     *
     * @param out the new logging/tracing PrintStream; to disable, set to <code>null</code>
     * @deprecated Use {@code setLogWriter}
     * @throws SecurityException if a security manager exists and its
     * {@code checkPermission} method denies permission to set the log stream.
     * @see SecurityManager#checkPermission
     * @see #getLogStream
     */
    @Deprecated(since="1.2")
    public static void setLogStream(java.io.PrintStream out) {

        SecurityManager sec = System.getSecurityManager();
        if (sec != null) {
            sec.checkPermission(SET_LOG_PERMISSION);
        }

        logStream = out;
        if ( out != null )
            logWriter = new java.io.PrintWriter(out);
        else
            logWriter = null;
    }

    
Retrieves the logging/tracing PrintStream that is used by the DriverManager
and all drivers.

See Also:
Returns:the logging/tracing PrintStream; if disabled, is null
Deprecated: Use getLogWriter
/**
     * Retrieves the logging/tracing PrintStream that is used by the <code>DriverManager</code>
     * and all drivers.
     *
     * @return the logging/tracing PrintStream; if disabled, is <code>null</code>
     * @deprecated  Use {@code getLogWriter}
     * @see #setLogStream
     */
    @Deprecated(since="1.2")
    public static java.io.PrintStream getLogStream() {
        return logStream;
    }

    
Prints a message to the current JDBC log stream.

Params:
  • message – a log or tracing message
/**
     * Prints a message to the current JDBC log stream.
     *
     * @param message a log or tracing message
     */
    public static void println(String message) {
        synchronized (logSync) {
            if (logWriter != null) {
                logWriter.println(message);

                // automatic flushing is never enabled, so we must do it ourselves
                logWriter.flush();
            }
        }
    }

    //------------------------------------------------------------------------

    // Indicates whether the class object that would be created if the code calling
    // DriverManager is accessible.
    private static boolean isDriverAllowed(Driver driver, Class<?> caller) {
        ClassLoader callerCL = caller != null ? caller.getClassLoader() : null;
        return isDriverAllowed(driver, callerCL);
    }

    private static boolean isDriverAllowed(Driver driver, ClassLoader classLoader) {
        boolean result = false;
        if (driver != null) {
            Class<?> aClass = null;
            try {
                aClass =  Class.forName(driver.getClass().getName(), true, classLoader);
            } catch (Exception ex) {
                result = false;
            }

             result = ( aClass == driver.getClass() ) ? true : false;
        }

        return result;
    }

    /*
     * Load the initial JDBC drivers by checking the System property
     * jdbc.drivers and then use the {@code ServiceLoader} mechanism
     */
    private static void ensureDriversInitialized() {
        if (driversInitialized) {
            return;
        }

        synchronized (lockForInitDrivers) {
            if (driversInitialized) {
                return;
            }
            String drivers;
            try {
                drivers = AccessController.doPrivileged(new PrivilegedAction<String>() {
                    public String run() {
                        return System.getProperty(JDBC_DRIVERS_PROPERTY);
                    }
                });
            } catch (Exception ex) {
                drivers = null;
            }
            // If the driver is packaged as a Service Provider, load it.
            // Get all the drivers through the classloader
            // exposed as a java.sql.Driver.class service.
            // ServiceLoader.load() replaces the sun.misc.Providers()

            AccessController.doPrivileged(new PrivilegedAction<Void>() {
                public Void run() {

                    ServiceLoader<Driver> loadedDrivers = ServiceLoader.load(Driver.class);
                    Iterator<Driver> driversIterator = loadedDrivers.iterator();

                    /* Load these drivers, so that they can be instantiated.
                     * It may be the case that the driver class may not be there
                     * i.e. there may be a packaged driver with the service class
                     * as implementation of java.sql.Driver but the actual class
                     * may be missing. In that case a java.util.ServiceConfigurationError
                     * will be thrown at runtime by the VM trying to locate
                     * and load the service.
                     *
                     * Adding a try catch block to catch those runtime errors
                     * if driver not available in classpath but it's
                     * packaged as service and that service is there in classpath.
                     */
                    try {
                        while (driversIterator.hasNext()) {
                            driversIterator.next();
                        }
                    } catch (Throwable t) {
                        // Do nothing
                    }
                    return null;
                }
            });

            println("DriverManager.initialize: jdbc.drivers = " + drivers);

            if (drivers != null && !drivers.equals("")) {
                String[] driversList = drivers.split(":");
                println("number of Drivers:" + driversList.length);
                for (String aDriver : driversList) {
                    try {
                        println("DriverManager.Initialize: loading " + aDriver);
                        Class.forName(aDriver, true,
                                ClassLoader.getSystemClassLoader());
                    } catch (Exception ex) {
                        println("DriverManager.Initialize: load failed: " + ex);
                    }
                }
            }

            driversInitialized = true;
            println("JDBC DriverManager initialized");
        }
    }


    //  Worker method called by the public getConnection() methods.
    private static Connection getConnection(
        String url, java.util.Properties info, Class<?> caller) throws SQLException {
        /*
         * When callerCl is null, we should check the application's
         * (which is invoking this class indirectly)
         * classloader, so that the JDBC driver class outside rt.jar
         * can be loaded from here.
         */
        ClassLoader callerCL = caller != null ? caller.getClassLoader() : null;
        if (callerCL == null || callerCL == ClassLoader.getPlatformClassLoader()) {
            callerCL = Thread.currentThread().getContextClassLoader();
        }

        if (url == null) {
            throw new SQLException("The url cannot be null", "08001");
        }

        println("DriverManager.getConnection(\"" + url + "\")");

        ensureDriversInitialized();

        // Walk through the loaded registeredDrivers attempting to make a connection.
        // Remember the first exception that gets raised so we can reraise it.
        SQLException reason = null;

        for (DriverInfo aDriver : registeredDrivers) {
            // If the caller does not have permission to load the driver then
            // skip it.
            if (isDriverAllowed(aDriver.driver, callerCL)) {
                try {
                    println("    trying " + aDriver.driver.getClass().getName());
                    Connection con = aDriver.driver.connect(url, info);
                    if (con != null) {
                        // Success!
                        println("getConnection returning " + aDriver.driver.getClass().getName());
                        return (con);
                    }
                } catch (SQLException ex) {
                    if (reason == null) {
                        reason = ex;
                    }
                }

            } else {
                println("    skipping: " + aDriver.getClass().getName());
            }

        }

        // if we got here nobody could connect.
        if (reason != null)    {
            println("getConnection failed: " + reason);
            throw reason;
        }

        println("getConnection: no suitable driver found for "+ url);
        throw new SQLException("No suitable driver found for "+ url, "08001");
    }


}

/*
 * Wrapper class for registered Drivers in order to not expose Driver.equals()
 * to avoid the capture of the Driver it being compared to as it might not
 * normally have access.
 */
class DriverInfo {

    final Driver driver;
    DriverAction da;
    DriverInfo(Driver driver, DriverAction action) {
        this.driver = driver;
        da = action;
    }

    @Override
    public boolean equals(Object other) {
        return (other instanceof DriverInfo)
                && this.driver == ((DriverInfo) other).driver;
    }

    @Override
    public int hashCode() {
        return driver.hashCode();
    }

    @Override
    public String toString() {
        return ("driver[className="  + driver + "]");
    }

    DriverAction action() {
        return da;
    }
}