The basic service for managing a set of JDBC drivers.
+ * NOTE: The {@link 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
+ *
+ * The DriverManager methods getConnection and
+ * getDrivers have been enhanced to support the Java Standard Edition
+ * Service Provider mechanism. JDBC 4.0 Drivers must
+ * include the file META-INF/services/java.sql.Driver. This file contains the name of the JDBC drivers
+ * implementation of java.sql.Driver. For example, to load the my.sql.Driver class,
+ * the META-INF/services/java.sql.Driver file would contain the entry:
+ *
+ * my.sql.Driver
+ *
+ *
+ * Applications no longer need to explictly load JDBC drivers using Class.forName(). Existing programs
+ * which currently load JDBC drivers using Class.forName() will continue to work without
+ * modification.
+ *
+ *
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 Driver
+ * @see Connection
+ */
+public class DriverManager {
+
+
+ /**
+ * The SQLPermission constant that allows the
+ * setting of the logging stream.
+ * @since 1.3
+ */
+ final static SQLPermission SET_LOG_PERMISSION =
+ new SQLPermission("setLog");
+
+ //--------------------------JDBC 2.0-----------------------------
+
+ /**
+ * Retrieves the log writer.
+ *
+ * The getLogWriter and setLogWriter
+ * methods should be used instead
+ * of the get/setlogStream methods, which are deprecated.
+ * @return a java.io.PrintWriter 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.
+ *
+ * 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.
+ *
+ * Starting with 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.
+ *
+ * @param 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
+ *
+ * @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.
+ *
+ * @param url a database url of the form
+ * jdbc:subprotocol:subname
+ * @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
+ */
+ public static Connection getConnection(String url,
+ java.util.Properties info) throws SQLException {
+
+ // Gets the classloader of the code that called this method, may
+ // be null.
+ ClassLoader callerCL = DriverManager.getCallerClassLoader();
+
+ return (getConnection(url, info, callerCL));
+ }
+
+ /**
+ * 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.
+ *
+ * @param url a database url of the form
+ * jdbc:subprotocol:subname
+ * @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
+ */
+ public static Connection getConnection(String url,
+ String user, String password) throws SQLException {
+ java.util.Properties info = new java.util.Properties();
+
+ // Gets the classloader of the code that called this method, may
+ // be null.
+ ClassLoader callerCL = DriverManager.getCallerClassLoader();
+
+ if (user != null) {
+ info.put("user", user);
+ }
+ if (password != null) {
+ info.put("password", password);
+ }
+
+ return (getConnection(url, info, callerCL));
+ }
+
+ /**
+ * 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.
+ *
+ * @param url a database url of the form
+ * jdbc:subprotocol:subname
+ * @return a connection to the URL
+ * @exception SQLException if a database access error occurs
+ */
+ public static Connection getConnection(String url)
+ throws SQLException {
+
+ java.util.Properties info = new java.util.Properties();
+
+ // Gets the classloader of the code that called this method, may
+ // be null.
+ ClassLoader callerCL = DriverManager.getCallerClassLoader();
+
+ return (getConnection(url, info, callerCL));
+ }
+
+ /**
+ * 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.
+ *
+ * @param url a database URL of the form
+ * jdbc:subprotocol:subname
+ * @return a Driver object representing a driver
+ * that can connect to the given URL
+ * @exception SQLException if a database access error occurs
+ */
+ public static Driver getDriver(String url)
+ throws SQLException {
+ java.util.Vector drivers = null;
+
+ println("DriverManager.getDriver(\"" + url + "\")");
+
+ if (!initialized) {
+ initialize();
+ }
+
+ synchronized (DriverManager.class){
+ // use the read copy of the drivers vector
+ drivers = readDrivers;
+ }
+
+ // Gets the classloader of the code that called this method, may
+ // be null.
+ ClassLoader callerCL = DriverManager.getCallerClassLoader();
+
+ // Walk through the loaded drivers attempting to locate someone
+ // who understands the given URL.
+ for (int i = 0; i < drivers.size(); i++) {
+ DriverInfo di = (DriverInfo)drivers.elementAt(i);
+ // If the caller does not have permission to load the driver then
+ // skip it.
+ if ( getCallerClass(callerCL, di.driverClassName ) !=
+ di.driverClass ) {
+ println(" skipping: " + di);
+ continue;
+ }
+ try {
+ println(" trying " + di);
+ if (di.driver.acceptsURL(url)) {
+ // Success!
+ println("getDriver returning " + di);
+ return (di.driver);
+ }
+ } catch (SQLException ex) {
+ // Drop through and try the next driver.
+ }
+ }
+
+ 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.
+ *
+ * @param driver the new JDBC Driver that is to be registered with the
+ * DriverManager
+ * @exception SQLException if a database access error occurs
+ */
+ public static synchronized void registerDriver(java.sql.Driver driver)
+ throws SQLException {
+ if (!initialized) {
+ initialize();
+ }
+
+ DriverInfo di = new DriverInfo();
+
+ di.driver = driver;
+ di.driverClass = driver.getClass();
+ di.driverClassName = di.driverClass.getName();
+
+ // Not Required -- drivers.addElement(di);
+
+ writeDrivers.addElement(di);
+ println("registerDriver: " + di);
+
+ /* update the read copy of drivers vector */
+ readDrivers = (java.util.Vector) writeDrivers.clone();
+
+ }
+
+ /**
+ * Drops a driver from the DriverManager's list.
+ * Applets can only deregister drivers from their own classloaders.
+ *
+ * @param driver the JDBC Driver to drop
+ * @exception SQLException if a database access error occurs
+ */
+ public static synchronized void deregisterDriver(Driver driver)
+ throws SQLException {
+ // Gets the classloader of the code that called this method,
+ // may be null.
+ ClassLoader callerCL = DriverManager.getCallerClassLoader();
+ println("DriverManager.deregisterDriver: " + driver);
+
+ // Walk through the loaded drivers.
+ int i;
+ DriverInfo di = null;
+ for (i = 0; i < writeDrivers.size(); i++) {
+ di = (DriverInfo)writeDrivers.elementAt(i);
+ if (di.driver == driver) {
+ break;
+ }
+ }
+ // If we can't find the driver just return.
+ if (i >= writeDrivers.size()) {
+ println(" couldn't find driver to unload");
+ return;
+ }
+
+ // If the caller does not have permission to load the driver then
+ // throw a security exception.
+ if (getCallerClass(callerCL, di.driverClassName ) != di.driverClass ) {
+ throw new SecurityException();
+ }
+
+ // Remove the driver. Other entries in drivers get shuffled down.
+ writeDrivers.removeElementAt(i);
+
+ /* update the read copy of drivers vector */
+ readDrivers = (java.util.Vector) writeDrivers.clone();
+ }
+
+ /**
+ * 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
+ *
+ * In the Java 2 SDK, Standard Edition, version 1.3 release, this method checks
+ * to see that there is an d.getClass().getName()
+ *
+ * @return the list of JDBC Drivers loaded by the caller's class loader
+ */
+ public static java.util.EnumerationDriverManager
+ * and all drivers.
+ *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.
+ *
+ * @param out the new logging/tracing PrintStream; to disable, set to null
+ * @deprecated
+ * @throws SecurityException if a security manager exists and its
+ * checkPermission method denies setting the log stream
+ *
+ * @see SecurityManager#checkPermission
+ * @see #getLogStream
+ */
+ 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.
+ *
+ * @return the logging/tracing PrintStream; if disabled, is null
+ * @deprecated
+ * @see #setLogStream
+ */
+ public static java.io.PrintStream getLogStream() {
+ return logStream;
+ }
+
+ /**
+ * 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();
+ }
+ }
+ }
+
+ //------------------------------------------------------------------------
+
+ // Returns the class object that would be created if the code calling the
+ // driver manager had loaded the driver class, or null if the class
+ // is inaccessible.
+ private static Class getCallerClass(ClassLoader callerClassLoader,
+ String driverClassName) {
+ Class callerC = null;
+
+ try {
+ callerC = Class.forName(driverClassName, true, callerClassLoader);
+ }
+ catch (Exception ex) {
+ callerC = null; // being very careful
+ }
+
+ return callerC;
+ }
+
+ private static void loadInitialDrivers() {
+ String drivers;
+ try {
+ drivers = (String) AccessController.doPrivileged(new PrivilegedAction() {
+ public Object run() {
+ return System.getProperty("jdbc.drivers");
+ }
+ });
+ } 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() {
+ public Object run() {
+
+ ServiceLoader