java.sql
Class DriverManager

java.lang.Object
  java.sql.DriverManager

public class DriverManager

extends Object

The basic service for managing a set of JDBC drivers.
NOTE: The DataSource interface, new in the JDBC 2.0 API, 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 the driver classes referenced in the "jdbc.drivers" system property. This allows a user to customize the JDBC Drivers used by their applications. For example in your ~/.hotjava/properties file you might specify:

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

A program can also explicitly load JDBC drivers at any time. For example, the my.sql.Driver is loaded with the following statement:

 Class.forName("my.sql.Driver");
 

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 classloader as the current applet or application.

Starting with the Java 2 SDK, Standard Edition, version 1.3, a logging stream can be set only if the proper permission has been granted. Normally this will be done with the tool PolicyTool, which can be used to grant permission java.sql.SQLPermission "setLog".

See Also:

Driver, Connection

Field Summary

private static Vector	drivers
private static boolean	initialized
private static int	loginTimeout
private static PrintStream	logStream
private static Object	logSync
private static PrintWriter	logWriter
(package private) static SQLPermission	SET_LOG_PERMISSION The SQLPermission constant that allows the setting of the logging stream.

Constructor Summary

private

DriverManager()

Method Summary

static void	deregisterDriver(Driver driver) Drops a driver from the DriverManager's list.
private static Class	getCallerClass(ClassLoader callerClassLoader, String driverClassName)
private static ClassLoader	getCallerClassLoader()
static Connection	getConnection(String url) Attempts to establish a connection to the given database URL.
static Connection	getConnection(String url, Properties info) Attempts to establish a connection to the given database URL.
private static Connection	getConnection(String url, Properties info, ClassLoader callerCL)
static Connection	getConnection(String url, String user, String password) Attempts to establish a connection to the given database URL.
static Driver	getDriver(String url) Attempts to locate a driver that understands the given URL.
static Enumeration	getDrivers() Retrieves an Enumeration with all of the currently loaded JDBC drivers to which the current caller has access.
static int	getLoginTimeout() Gets the maximum time in seconds that a driver can wait when attempting to log in to a database.
static PrintStream	getLogStream() Deprecated.
static PrintWriter	getLogWriter() Retrieves the log writer.
(package private) static void	initialize()
private static void	loadInitialDrivers()
static void	println(String message) Prints a message to the current JDBC log stream.
static void	registerDriver(Driver driver) Registers the given driver with the DriverManager.
static void	setLoginTimeout(int seconds) Sets the maximum time in seconds that a driver will wait while attempting to connect to a database.
static void	setLogStream(PrintStream out) Deprecated.
static void	setLogWriter(PrintWriter out) Sets the logging/tracing PrintWriter object that is used by the DriverManager and all drivers.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

SET_LOG_PERMISSION

static final SQLPermission SET_LOG_PERMISSION

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

Since:

1.3

drivers

private static Vector drivers

loginTimeout

private static int loginTimeout

logWriter

private static PrintWriter logWriter

logStream

private static PrintStream logStream

initialized

private static boolean initialized

logSync

private static Object logSync

Constructor Detail

DriverManager

private DriverManager()

Method Detail

getLogWriter

public static PrintWriter getLogWriter()

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

Returns:

a java.io.PrintWriter object

Since:

1.2

See Also:

setLogWriter(java.io.PrintWriter)

setLogWriter

public static void setLogWriter(PrintWriter out)

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

There is a minor versioning problem created by the introduction of the method setLogWriter. The method setLogWriter cannot create a PrintStream object that will be returned by getLogStream---the Java platform does not provide a backward conversion. As a result, a new application that uses setLogWriter and also uses a JDBC 1.0 driver that uses getLogStream will likely not see debugging information written by that driver.

In the Java 2 SDK, Standard Edition, version 1.3 release, this method checks to see that there is an SQLPermission object before setting the logging stream. If a SecurityManager exists and its checkPermission method denies setting the log writer, this method throws a java.lang.SecurityException.

Parameters:

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 setting the log writer

Since:

1.2

See Also:

SecurityManager.checkPermission(java.security.Permission), getLogWriter()

getConnection

public static Connection getConnection(String url,
                                       Properties info)
                                throws SQLException

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.

Parameters:

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

Returns:

a Connection to the URL

Throws:

SQLException - if a database access error occurs

getConnection

public static Connection getConnection(String url,
                                       String user,
                                       String password)
                                throws SQLException

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.

Parameters:

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

Returns:

a connection to the URL

Throws:

SQLException - if a database access error occurs

getConnection

public static Connection getConnection(String url)
                                throws SQLException

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.

Parameters:

url - a database url of the form jdbc:subprotocol:subname

Returns:

a connection to the URL

Throws:

SQLException - if a database access error occurs

getDriver

public static Driver getDriver(String url)
                        throws SQLException

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.

Parameters:

url - a database URL of the form jdbc:subprotocol:subname

Returns:

a Driver object representing a driver that can connect to the given URL

Throws:

SQLException - if a database access error occurs

registerDriver

public static void registerDriver(Driver driver)
                           throws SQLException

Registers the given driver with the DriverManager. A newly-loaded driver class should call the method registerDriver to make itself known to the DriverManager.

Parameters:

driver - the new JDBC Driver that is to be registered with the DriverManager

Throws:

SQLException - if a database access error occurs

deregisterDriver

public static void deregisterDriver(Driver driver)
                             throws SQLException

Drops a driver from the DriverManager's list. Applets can only deregister drivers from their own classloaders.

Parameters:

driver - the JDBC Driver to drop

Throws:

SQLException - if a database access error occurs

getDrivers

public static Enumeration getDrivers()

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()

Returns:

the list of JDBC Drivers loaded by the caller's class loader

setLoginTimeout

public static void setLoginTimeout(int seconds)

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

Parameters:

seconds - the login time limit in seconds

See Also:

getLoginTimeout()

getLoginTimeout

public static int getLoginTimeout()

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

Returns:

the driver login time limit in seconds

See Also:

setLoginTimeout(int)

setLogStream

public static void setLogStream(PrintStream out)

Deprecated.

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

In the Java 2 SDK, Standard Edition, version 1.3 release, this method checks to see that there is an SQLPermission object before setting the logging stream. If a SecurityManager exists and its checkPermission method denies setting the log writer, this method throws a java.lang.SecurityException.

Parameters:

out - the new logging/tracing PrintStream; to disable, set to null

Throws:

SecurityException - if a security manager exists and its checkPermission method denies setting the log stream

See Also:

SecurityManager.checkPermission(java.security.Permission), getLogStream()

getLogStream

public static PrintStream getLogStream()

Deprecated.

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

Returns:

the logging/tracing PrintStream; if disabled, is null

See Also:

setLogStream(java.io.PrintStream)

println

public static void println(String message)

Prints a message to the current JDBC log stream.

Parameters:

message - a log or tracing message

getCallerClass

private static Class getCallerClass(ClassLoader callerClassLoader,
                                    String driverClassName)

loadInitialDrivers

private static void loadInitialDrivers()

getConnection

private static Connection getConnection(String url,
                                        Properties info,
                                        ClassLoader callerCL)
                                 throws SQLException

Throws:

SQLException

initialize

static void initialize()

getCallerClassLoader

private static ClassLoader getCallerClassLoader()