Package org.apache.tomcat.dbcp.dbcp2
Database Connection Pool API.
Overview in Dialog FormQ: How do I use the DBCP package?
A: There are two primary ways to access the DBCP pool, as a Driver
, or as a
DataSource
. You'll want to create an instance of
PoolingDriver
or PoolingDataSource
. When using one
of these interfaces, you can just use your JDBC objects the way you normally would. Closing a
Connection
will simply return it to its pool.
Q: But PoolingDriver
and
PoolingDataSource
both expect an
ObjectPool
as an input. Where do I get one of those?
A: The ObjectPool
interface is defined in Commons Pool. You can use one
of the provided implementations such as GenericObjectPool
or
SoftReferenceObjectPool
or you can create your own.
Q: Ok, I've found an ObjectPool
implementation that I think suits my
connection pooling needs. But it wants a PooledObjectFactory
.
What should I use for that?
A: The DBCP package provides a class for this purpose. It's called
PoolableConnectionFactory
. It implements the factory and lifecycle methods of
PooledObjectFactory
for Connection
s. But it doesn't create the
actual database Connection
s itself, it uses a ConnectionFactory
for
that. The PoolableConnectionFactory
will take Connection
s created
by the ConnectionFactory
and wrap them with classes that implement the pooling
behaviour.
Several implementations of ConnectionFactory
are provided--one that uses
DriverManager
to create connections
(DriverManagerConnectionFactory
), one that uses a Driver
to create
connections (DriverConnectionFactory
), one that uses a DataSource
to create connections (DataSourceConnectionFactory
).
Q: I think I'm starting to get it, but can you walk me though it again?
A: Sure. Let's assume you want to create a DataSource
that pools Connection
s.
Let's also assume that those pooled Connection
s should be obtained from the
DriverManager
. You'll want to create a PoolingDataSource
.
The PoolingDataSource
uses an underlying ObjectPool
to create and store its Connection
.
To create a ObjectPool
, you'll need a
PooledObjectFactory
that creates the actual Connection
s. That's
what PoolableConnectionFactory
is for.
To create the PoolableConnectionFactory
, you'll need at least two things:
- A
ConnectionFactory
from which the actual databaseConnection
s will be obtained. - An empty and factory-less
ObjectPool
in which theConnection
s will be stored.
When you pass anObjectPool
into thePoolableConnectionFactory
, it will automatically register itself as thePooledObjectFactory
for that pool.
In code, that might look like this:
GenericObjectPool connectionPool = new GenericObjectPool(null); ConnectionFactory connectionFactory = new DriverManagerConnectionFactory("jdbc:some:connect:string", "userName", "password"); ObjectName oName = new ObjectName("MyTests:DataSource=test"); // or null to not use JMX PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(connectionFactory, oName); PoolingDataSource dataSource = new PoolingDataSource(connectionPool);
To create a PoolingDriver
, we do the same thing, except that instead of creating a
DataSource
on the last line, we create a PoolingDriver
, and
register the connectionPool
with it. E.g.,:
GenericObjectPool connectionPool = new GenericObjectPool(null); ConnectionFactory connectionFactory = new DriverManagerConnectionFactory("jdbc:some:connect:string", "userName", "password"); ObjectName oName = new ObjectName("MyTests:DataSource=test"); // or null to not use JMX PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(connectionFactory, oName); PoolingDriver driver = new PoolingDriver(); driver.registerPool("example", connectionPool);
Since the PoolingDriver
registers itself with the DriverManager
when it is created, now you can just go to the DriverManager
to create your
Connection
s, like you normally would:
Connection conn = DriverManager.getConnection("jdbc:apache:commons:dbcp:example");
-
ClassDescriptionTracks connection usage for recovering and reporting abandoned connections.Basic implementation of
javax.sql.DataSource
that is configured via JavaBeans properties.JNDI object factory that creates an instance ofBasicDataSource
that has been configured based on theRefAddr
values of the specifiedReference
, which must match the names and data types of theBasicDataSource
bean properties with the following exceptions:connectionInitSqls
must be passed to this factory as a single String using semicolon to delimit the statements whereasBasicDataSource
requires a collection of Strings.Interface to keep API compatibility.Abstract factory interface for creatingConnection
s.Constants.ADataSource
-based implementation ofConnectionFactory
.Defines the methods that will be made available via JMX.A base delegating implementation ofCallableStatement
.DelegatingConnection<C extends Connection>A base delegating implementation ofConnection
.A base delegating implementation ofDatabaseMetaData
.A base delegating implementation ofPreparedStatement
.A base delegating implementation ofResultSet
.A base delegating implementation ofStatement
.ADriver
-based implementation ofConnectionFactory
.ADriverManager
-based implementation ofConnectionFactory
.Defines bridge methods to JDBC 4.1 (Java 7 or above) methods to allow call sites to operate safely (withoutAbstractMethodError
) when using a JDBC driver written for JDBC 4.0 (Java 6 or above).An exception wrapping a list of exceptions.ADelegatingCallableStatement
that cooperates withPoolingConnection
to implement a pool ofCallableStatement
s.A delegating connection that, rather than closing the underlying connection, returns itself to anObjectPool
when closed.APooledObjectFactory
that createsPoolableConnection
s.Defines the attributes and methods that will be exposed via JMX forPoolableConnection
instances.ADelegatingPreparedStatement
that cooperates withPoolingConnection
to implement a pool ofPreparedStatement
s.ADelegatingConnection
that poolsPreparedStatement
s.Statement types.PoolingDataSource<C extends Connection>A key uniquely identifyingPreparedStatement
s.An SQLException based on a list of Throwable causes.Class for logging swallowed exceptions.Utility methods.