org.apache.xalan.lib.sql
Class DefaultConnectionPool

java.lang.Object
  org.apache.xalan.lib.sql.DefaultConnectionPool

All Implemented Interfaces:

ConnectionPool

public class DefaultConnectionPool

extends Object

implements ConnectionPool

For internal connectiones, i.e. Connection information supplies in the Stylesheet. The Default Connection Pool will be used.

Field Summary

private static boolean	DEBUG
private Properties	m_ConnectionProtocol Always implement the properties mechinism, if the Password or Username is set seperatly then we will add them to the property manually.
private String	m_driver The basic information to make a JDBC Connection
private Object	m_Driver A placeholder thast will keep the driver loaded between calls.
private boolean	m_IsActive Are we active ??
private Vector	m_pool Storage for the PooledConnections
private int	m_PoolMinSize The mimimum size of the connection pool, if the number of available connections falls below this mark, min connections will be allocated.
private String	m_url

Constructor Summary

DefaultConnectionPool()

Method Summary

private void	addConnection(PooledConnection value)
private Connection	createConnection()
protected void	finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
void	freeUnused() Go through the connection pool and release any connections that are not InUse;
Connection	getConnection() Retrive a database connection from the pool
boolean	hasActiveConnections() Is our ConnectionPool have any connections that are still in Use ??
void	initializePool()
boolean	isEnabled() Return our current Active state
void	releaseConnection(Connection con) Return a connection to the pool, the connection may be closed if the pool is inactive or has exceeded the max number of free connections
void	releaseConnectionOnError(Connection con) Provide a mechinism to return a connection to the pool on Error.
void	setDriver(String d) Set the driver call to be used to create connections
void	setMinConnections(int n) Override the current number of connections to keep in the pool.
void	setPassword(String p) Set the password in the property set.
void	setPoolEnabled(boolean flag) The Pool can be Enabled and Disabled.
void	setProtocol(Properties p) The Protocol string is used to pass in other connection properties.
void	setURL(String url) Set the url used to connect to the database
void	setUser(String u) Set the user name in the property set
boolean	testConnection() Try to aquire a new connection, if it succeeds then return true, else return false.

Methods inherited from class java.lang.Object

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

Field Detail

m_Driver

private Object m_Driver

A placeholder thast will keep the driver loaded between calls.

DEBUG

private static final boolean DEBUG

See Also:

Constant Field Values

m_driver

private String m_driver

The basic information to make a JDBC Connection

m_url

private String m_url

m_PoolMinSize

private int m_PoolMinSize

The mimimum size of the connection pool, if the number of available connections falls below this mark, min connections will be allocated. The Connection Pool will always be somewhere between MinSize and MinSize*2

m_ConnectionProtocol

private Properties m_ConnectionProtocol

Always implement the properties mechinism, if the Password or Username is set seperatly then we will add them to the property manually.

m_pool

private Vector m_pool

Storage for the PooledConnections

m_IsActive

private boolean m_IsActive

Are we active ??

Constructor Detail

DefaultConnectionPool

public DefaultConnectionPool()

Method Detail

isEnabled

public boolean isEnabled()

Return our current Active state

Specified by:

isEnabled in interface ConnectionPool

Returns:

setDriver

public void setDriver(String d)

Set the driver call to be used to create connections

Specified by:

setDriver in interface ConnectionPool

Parameters:

d -

Returns:

setURL

public void setURL(String url)

Set the url used to connect to the database

Specified by:

setURL in interface ConnectionPool

Parameters:

url -

Returns:

freeUnused

public void freeUnused()

Go through the connection pool and release any connections that are not InUse;

Specified by:

freeUnused in interface ConnectionPool

Returns:

hasActiveConnections

public boolean hasActiveConnections()

Is our ConnectionPool have any connections that are still in Use ??

Specified by:

hasActiveConnections in interface ConnectionPool

Returns:

setPassword

public void setPassword(String p)

Set the password in the property set.

Specified by:

setPassword in interface ConnectionPool

Parameters:

p -

Returns:

setUser

public void setUser(String u)

Set the user name in the property set

Specified by:

setUser in interface ConnectionPool

Parameters:

u -

Returns:

setProtocol

public void setProtocol(Properties p)

The Protocol string is used to pass in other connection properties. A properties file is a general purpose container

Specified by:

setProtocol in interface ConnectionPool

Parameters:

p -

Returns:

setMinConnections

public void setMinConnections(int n)

Override the current number of connections to keep in the pool. This setting will only have effect on a new pool or when a new connection is requested and there is less connections that this setting.

Specified by:

setMinConnections in interface ConnectionPool

Parameters:

n -

Returns:

testConnection

public boolean testConnection()

Try to aquire a new connection, if it succeeds then return true, else return false. Note: This method will cause the connection pool to be built.

Specified by:

testConnection in interface ConnectionPool

Returns:

getConnection

public Connection getConnection()
                         throws IllegalArgumentException,
                                SQLException

Description copied from interface: ConnectionPool

Retrive a database connection from the pool

Specified by:

getConnection in interface ConnectionPool

Returns:

Connection

Throws:

SQLException

IllegalArgumentException

releaseConnection

public void releaseConnection(Connection con)
                       throws SQLException

Description copied from interface: ConnectionPool

Return a connection to the pool, the connection may be closed if the pool is inactive or has exceeded the max number of free connections

Specified by:

releaseConnection in interface ConnectionPool

Parameters:

con -

Returns:

Throws:

SQLException

releaseConnectionOnError

public void releaseConnectionOnError(Connection con)
                              throws SQLException

Description copied from interface: ConnectionPool

Provide a mechinism to return a connection to the pool on Error. A good default behaviour is to close this connection and build a new one to replace it. Some JDBC impl's won't allow you to reuse a connection after an error occurs.

Specified by:

releaseConnectionOnError in interface ConnectionPool

Parameters:

con -

Returns:

Throws:

SQLException

createConnection

private Connection createConnection()
                             throws SQLException

Returns:

Throws:

SQLException

initializePool

public void initializePool()
                    throws IllegalArgumentException,
                           SQLException

Returns:

Throws:

IllegalArgumentException

SQLException

addConnection

private void addConnection(PooledConnection value)

Parameters:

value -

Returns:

finalize

protected void finalize()
                 throws Throwable

Description copied from class: Object

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. A subclass overrides the finalize method to dispose of system resources or to perform other cleanup.

The general contract of finalize is that it is invoked if and when the Java^TM virtual machine has determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, except as a result of an action taken by the finalization of some other object or class which is ready to be finalized. The finalize method may take any action, including making this object available again to other threads; the usual purpose of finalize, however, is to perform cleanup actions before the object is irrevocably discarded. For example, the finalize method for an object that represents an input/output connection might perform explicit I/O transactions to break the connection before the object is permanently discarded.

The finalize method of class Object performs no special action; it simply returns normally. Subclasses of Object may override this definition.

The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.

After the finalize method has been invoked for an object, no further action is taken until the Java virtual machine has again determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, including possible actions by other objects or classes which are ready to be finalized, at which point the object may be discarded.

The finalize method is never invoked more than once by a Java virtual machine for any given object.

Any exception thrown by the finalize method causes the finalization of this object to be halted, but is otherwise ignored.

Overrides:

finalize in class Object

Returns:

Throws:

Throwable

setPoolEnabled

public void setPoolEnabled(boolean flag)

The Pool can be Enabled and Disabled. Disabling the pool closes all the outstanding Unused connections and any new connections will be closed upon release.

Specified by:

setPoolEnabled in interface ConnectionPool

Parameters:

flag - Control the Connection Pool. If it is enabled then Connections will actuall be held around. If disabled then all unused connections will be instantly closed and as connections are released they are closed and removed from the pool.

Returns: