org.hsqldb.jdbc
Class JDBCDriver

java.lang.Object
  org.hsqldb.jdbc.JDBCDriver

All Implemented Interfaces:

Driver

public class JDBCDriver
extends Object
implements Driver

Provides the java.sql.Driver interface implementation required by the JDBC specification.

The Java SQL framework allows for multiple database drivers.

The DriverManager will try to load as many drivers as it can find and then for any given connection request, it will ask each driver in turn to try to connect to the target URL.

The application developer will normally not need to call any function of the Driver directly. All required calls are made by the DriverManager.

HSQLDB-Specific Information:

When the HSQL Database Engine Driver class is loaded, it creates an instance of itself and register it with the DriverManager. This means that a user can load and register the HSQL Database Engine driver by calling:

  Class.forName("org.hsqldb.jdbc.JDBCDriver")
  

For detailed information about how to obtain HSQLDB JDBC Connections, please see JDBCConnection.

JRE 1.1.x Notes:

In general, JDBC 2 support requires Java 1.2 and above, and JDBC3 requires Java 1.4 and above. In HSQLDB, support for methods introduced in different versions of JDBC depends on the JDK version used for compiling and building HSQLDB.

Since 1.7.0, it is possible to build the product so that all JDBC 2 methods can be called while executing under the version 1.1.x Java Runtime Environment^TM. However, in addition to this technique requiring explicit casts to the org.hsqldb.jdbc.* classes, some of the method calls also require int values that are defined only in the JDBC 2 or greater version of the ResultSet interface. For this reason, when the product is compiled under JDK 1.1.x, these values are defined in JDBCResultSet.

In a JRE 1.1.x environment, calling JDBC 2 methods that take or return the JDBC2-only ResultSet values can be achieved by referring to them in parameter specifications and return value comparisons, respectively, as follows:

 JDBCResultSet.FETCH_FORWARD
 JDBCResultSet.TYPE_FORWARD_ONLY
 JDBCResultSet.TYPE_SCROLL_INSENSITIVE
 JDBCResultSet.CONCUR_READ_ONLY
 // etc.
 

However, please note that code written to use HSQLDB JDBC 2 features under JDK 1.1.x will not be compatible for use with other JDBC 2 drivers. Please also note that this feature is offered solely as a convenience to developers who must work under JDK 1.1.x due to operating constraints, yet wish to use some of the more advanced features available under the JDBC 2 specification.

JDBC 4.0 notes:

Starting with JDBC 4.0 (JDK 1.6), the DriverManager methods getConnection and getDrivers have been enhanced to support the Java Standard Edition Service Provider mechanism. When built under a Java runtime that supports JDBC 4.0, HSQLDB distribution jars containing the Driver implementation also include the file META-INF/services/java.sql.Driver. This file contains the fully qualified class name ('org.hsqldb.jdbc.JDBCDriver') of the HSQLDB implementation of java.sql.Driver.

Hence, under JDBC 4.0 or greater, applications no longer need to explictly load the HSQLDB JDBC driver using Class.forName(). Of course, existing programs which do load JDBC drivers using Class.forName() will continue to work without modification.

Author:

Campbell Boucher-Burnet (boucherb@users dot sourceforge.net), Fred Toussi (fredt@users dot sourceforge.net)

See Also:

JDBCConnection

Field Summary

static JDBCDriver	driverInstance
ThreadLocal<JDBCConnection>	threadConnection As a separate instance of this class is registered with DriverManager for each class loader, the threadConnection is not declared as static.

Constructor Summary

JDBCDriver()
Default constructor

Method Summary

boolean	acceptsURL(String url) Returns true if the driver thinks that it can open a connection to the given URL.
Connection	connect(String url, Properties info) Attempts to make a database connection to the given URL.
static Connection	getConnection(String url, Properties info) The static equivalent of the connect(String,Properties) method.
int	getMajorVersion() Gets the driver's major version number.
int	getMinorVersion() Gets the driver's minor version number.
Logger	getParentLogger() Return the parent Logger of all the Loggers used by this driver.
DriverPropertyInfo[]	getPropertyInfo(String url, Properties info) Gets information about the possible properties for this driver.
boolean	jdbcCompliant() Reports whether this driver is a genuine JDBC CompliantTM driver.

Methods inherited from class java.lang.Object

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

Field Detail

driverInstance

public static JDBCDriver driverInstance

threadConnection

public final ThreadLocal<JDBCConnection> threadConnection

As a separate instance of this class is registered with DriverManager for each class loader, the threadConnection is not declared as static. The registered instance is kept to allow access to the its threadConnection.

Constructor Detail

JDBCDriver

public JDBCDriver()

Default constructor

Method Detail

connect

public Connection connect(String url,
                          Properties info)
                   throws SQLException

Attempts to make a database connection to the given URL.

Returns "null" if this is the wrong kind of driver to connect to the given URL. This will be common, as when the JDBC driver manager is asked to connect to a given URL it passes the URL to each loaded driver in turn.

The driver throws an SQLException if it is the right driver to connect to the given URL but has trouble connecting to the database.

The java.util.Properties argument can be used to pass arbitrary string tag/value pairs as connection arguments. Normally at least "user" and "password" properties should be included in the Properties object.

HSQLDB-Specific Information:

For the HSQL Database Engine, at least "user" and "password" properties should be included in the Properties.

From version 1.7.1, two optional properties are supported:

• get_column_name (default true) - if set to false, a ResultSetMetaData.getColumnName() call will return the user defined label (getColumnLabel()) instead of the column name.
  This property is available in order to achieve compatibility with certain non-HSQLDB JDBC driver implementations.
• strict_md if set to true, some ResultSetMetaData methods return more strict values for compatibility reasons.

From version 1.8.0.x, strict_md is deprecated (ignored) because metadata reporting is always strict (JDBC-compliant), and three new optional properties are supported:

• ifexits (default false) - when true, an exception is raised when attempting to connect to an in-process file: or mem: scheme database instance if it has not yet been created. When false, an in-process file: or mem: scheme database instance is created automatically if it has not yet been created. This property does not apply to requests for network or res: (i.e. files_in_jar) scheme connections.
• shutdown (default false) - when true, the the target database mimics the behaviour of 1.7.1 and older versions. When the last connection to a database is closed, the database is automatically shut down. The property takes effect only when the first connection is made to the database. This means the connection that opens the database. It has no effect if used with subsequent, simultaneous connections.
  This command has two uses. One is for test suites, where connections to the database are made from one JVM context, immediately followed by another context. The other use is for applications where it is not easy to configure the environment to shutdown the database. Examples reported by users include web application servers, where the closing of the last connection coincides with the web application being shut down.
• default_schema - backwards compatibility feature. To be used for clients written before HSQLDB schema support. Denotes whether to use the default schema when a schema qualifier is not included in a database object's SQL identifier character sequence. Also affects the semantics of DatabaseMetaData calls that supply null-valued schemaNamePattern parameter values.

Specified by:

connect in interface Driver

Parameters:

url - the URL of the database to which to connect

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 object that represents a connection to the URL

Throws:

SQLException - if a database access error occurs

getConnection

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

The static equivalent of the connect(String,Properties) method.

Parameters:

url - the URL of the database to which to connect

info - a list of arbitrary string tag/value pairs as connection arguments including at least at a "user" and a "password" property

Returns:

a Connection object that represents a connection to the URL

Throws:

SQLException - if a database access error occurs

acceptsURL

public boolean acceptsURL(String url)

Returns true if the driver thinks that it can open a connection to the given URL. Typically drivers will return true if they understand the subprotocol specified in the URL and false if they don't.

Specified by:

acceptsURL in interface Driver

Parameters:

url - the URL of the database

Returns:

true if this driver can connect to the given URL

getPropertyInfo

public DriverPropertyInfo[] getPropertyInfo(String url,
                                            Properties info)

Gets information about the possible properties for this driver.

The getPropertyInfo method is intended to allow a generic GUI tool to discover what properties it should prompt a human for in order to get enough information to connect to a database. Note that depending on the values the human has supplied so far, additional values may become necessary, so it may be necessary to iterate though several calls to getPropertyInfo.

HSQLDB-Specific Information:

HSQLDB uses the values submitted in info to set the value for each DriverPropertyInfo object returned. It does not use the default value that it would use for the property if the value is null.

Specified by:

getPropertyInfo in interface Driver

Parameters:

url - the URL of the database to which to connect

info - a proposed list of tag/value pairs that will be sent on connect open

Returns:

an array of DriverPropertyInfo objects describing possible properties. This array may be an empty array if no properties are required.

getMajorVersion

public int getMajorVersion()

Gets the driver's major version number.

Specified by:

getMajorVersion in interface Driver

Returns:

this driver's major version number

getMinorVersion

public int getMinorVersion()

Gets the driver's minor version number.

Specified by:

getMinorVersion in interface Driver

Returns:

this driver's minor version number

jdbcCompliant

public boolean jdbcCompliant()

Reports whether this driver is a genuine JDBC Compliant^TM driver. A driver may only report true here if it passes the JDBC compliance tests; otherwise it is required to return false.

JDBC compliance requires full support for the JDBC API and full support for SQL 92 Entry Level.

HSQLDB-Specific Information:

HSQLDB 2.0 is aimed to be compliant with JDBC 4.0 specification. It supports SQL 92 Entry Level and beyond.

This method is not intended to encourage the development of non-JDBC compliant drivers, but is a recognition of the fact that some vendors are interested in using the JDBC API and framework for lightweight databases that do not support full database functionality, or for special databases such as document information retrieval where a SQL implementation may not be feasible.

Specified by:

jdbcCompliant in interface Driver

Returns:

true if this driver is JDBC Compliant; false otherwise

getParentLogger

public Logger getParentLogger()
                       throws SQLFeatureNotSupportedException

Return the parent Logger of all the Loggers used by this driver. This should be the Logger farthest from the root Logger that is still an ancestor of all of the Loggers used by this driver. Configuring this Logger will affect all of the log messages generated by the driver. In the worst case, this may be the root Logger.

Returns:

the parent Logger for this driver

Throws:

SQLFeatureNotSupportedException - if the driver does not use java.util.logging.

Since:

JDK 1.7 M11 2010/09/10 (b123), HSQLDB 2.0.1