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java/org/apache/tomcat/dbcp/dbcp2/package-info.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * <p>
+ * Database Connection Pool API.
+ * </p>
+ *
+ * <b>Overview in Dialog Form</b>
+ * <p>
+ * Q: How do I use the DBCP package?
+ * </p>
+ * <p>
+ * A: There are two primary ways to access the DBCP pool, as a {@link java.sql.Driver Driver}, or as a
+ * {@link javax.sql.DataSource DataSource}. You'll want to create an instance of
+ * {@link org.apache.tomcat.dbcp.dbcp2.PoolingDriver} or {@link org.apache.tomcat.dbcp.dbcp2.PoolingDataSource}. When using one
+ * of these interfaces, you can just use your JDBC objects the way you normally would. Closing a
+ * {@link java.sql.Connection} will simply return it to its pool.
+ * </p>
+ * <p>
+ * Q: But {@link org.apache.tomcat.dbcp.dbcp2.PoolingDriver PoolingDriver} and
+ * {@link org.apache.tomcat.dbcp.dbcp2.PoolingDataSource PoolingDataSource} both expect an
+ * {@link org.apache.tomcat.dbcp.pool2.ObjectPool ObjectPool} as an input. Where do I get one of those?
+ * </p>
+ * <p>
+ * A: The {@link org.apache.tomcat.dbcp.pool2.ObjectPool ObjectPool} interface is defined in Commons Pool. You can use one
+ * of the provided implementations such as {@link org.apache.tomcat.dbcp.pool2.impl.GenericObjectPool GenericObjectPool} or
+ * {@link org.apache.tomcat.dbcp.pool2.impl.SoftReferenceObjectPool SoftReferenceObjectPool} or you can create your own.
+ * </p>
+ * <p>
+ * Q: Ok, I've found an {@link org.apache.tomcat.dbcp.pool2.ObjectPool ObjectPool} implementation that I think suits my
+ * connection pooling needs. But it wants a {@link org.apache.tomcat.dbcp.pool2.PooledObjectFactory PooledObjectFactory}.
+ * What should I use for that?
+ * </p>
+ * <p>
+ * A: The DBCP package provides a class for this purpose. It's called
+ * {@link org.apache.tomcat.dbcp.dbcp2.PoolableConnectionFactory}. It implements the factory and lifecycle methods of
+ * {@link org.apache.tomcat.dbcp.pool2.PooledObjectFactory} for {@link java.sql.Connection}s. But it doesn't create the
+ * actual database {@link java.sql.Connection}s itself, it uses a {@link org.apache.tomcat.dbcp.dbcp2.ConnectionFactory} for
+ * that. The {@link org.apache.tomcat.dbcp.dbcp2.PoolableConnectionFactory} will take {@link java.sql.Connection}s created
+ * by the {@link org.apache.tomcat.dbcp.dbcp2.ConnectionFactory} and wrap them with classes that implement the pooling
+ * behaviour.
+ * </p>
+ * <p>
+ * Several implementations of {@link org.apache.tomcat.dbcp.dbcp2.ConnectionFactory} are provided--one that uses
+ * {@link java.sql.DriverManager} to create connections
+ * ({@link org.apache.tomcat.dbcp.dbcp2.DriverManagerConnectionFactory}), one that uses a {@link java.sql.Driver} to create
+ * connections ({@link org.apache.tomcat.dbcp.dbcp2.DriverConnectionFactory}), one that uses a {@link javax.sql.DataSource}
+ * to create connections ({@link org.apache.tomcat.dbcp.dbcp2.DataSourceConnectionFactory}).
+ * </p>
+ * <p>
+ * Q: I think I'm starting to get it, but can you walk me though it again?
+ * </p>
+ * <p>
+ * A: Sure. Let's assume you want to create a {@link javax.sql.DataSource} that pools {@link java.sql.Connection}s.
+ * Let's also assume that those pooled {@link java.sql.Connection}s should be obtained from the
+ * {@link java.sql.DriverManager}. You'll want to create a {@link org.apache.tomcat.dbcp.dbcp2.PoolingDataSource}.
+ * </p>
+ * <p>
+ * The {@link org.apache.tomcat.dbcp.dbcp2.PoolingDataSource} uses an underlying {@link org.apache.tomcat.dbcp.pool2.ObjectPool}
+ * to create and store its {@link java.sql.Connection}.
+ * </p>
+ * <p>
+ * To create a {@link org.apache.tomcat.dbcp.pool2.ObjectPool}, you'll need a
+ * {@link org.apache.tomcat.dbcp.pool2.PooledObjectFactory} that creates the actual {@link java.sql.Connection}s. That's
+ * what {@link org.apache.tomcat.dbcp.dbcp2.PoolableConnectionFactory} is for.
+ * </p>
+ * <p>
+ * To create the {@link org.apache.tomcat.dbcp.dbcp2.PoolableConnectionFactory}, you'll need at least two things:
+ * </p>
+ * <ol>
+ * <li>A {@link org.apache.tomcat.dbcp.dbcp2.ConnectionFactory} from which the actual database {@link java.sql.Connection}s
+ * will be obtained.</li>
+ * <li>An empty and factory-less {@link org.apache.tomcat.dbcp.pool2.ObjectPool} in which the {@link java.sql.Connection}s
+ * will be stored. <br>
+ * When you pass an {@link org.apache.tomcat.dbcp.pool2.ObjectPool} into the
+ * {@link org.apache.tomcat.dbcp.dbcp2.PoolableConnectionFactory}, it will automatically register itself as the
+ * {@link org.apache.tomcat.dbcp.pool2.PooledObjectFactory} for that pool.</li>
+ * </ol>
+ * <p>
+ * In code, that might look like this:
+ * </p>
+ *
+ * <pre>
+ * GenericObjectPool connectionPool = new GenericObjectPool(null);
+ * ConnectionFactory connectionFactory = new DriverManagerConnectionFactory("jdbc:some:connect:string", "userName",
+ *         "password");
+ * PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(connectionFactory,
+ *         connectionPool, null, null, false, true);
+ * PoolingDataSource dataSource = new PoolingDataSource(connectionPool);
+ * </pre>
+ * <p>
+ * To create a {@link org.apache.tomcat.dbcp.dbcp2.PoolingDriver}, we do the same thing, except that instead of creating a
+ * {@link javax.sql.DataSource} on the last line, we create a {@link org.apache.tomcat.dbcp.dbcp2.PoolingDriver}, and
+ * register the {@code connectionPool} with it. E.g.,:
+ * </p>
+ *
+ * <pre>
+ * GenericObjectPool connectionPool = new GenericObjectPool(null);
+ * ConnectionFactory connectionFactory = new DriverManagerConnectionFactory("jdbc:some:connect:string", "userName",
+ *         "password");
+ * PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(connectionFactory,
+ *         connectionPool, null, null, false, true);
+ * PoolingDriver driver = new PoolingDriver();
+ * driver.registerPool("example", connectionPool);
+ * </pre>
+ * <p>
+ * Since the {@link org.apache.tomcat.dbcp.dbcp2.PoolingDriver} registers itself with the {@link java.sql.DriverManager}
+ * when it is created, now you can just go to the {@link java.sql.DriverManager} to create your
+ * {@link java.sql.Connection}s, like you normally would:
+ * </p>
+ *
+ * <pre>
+ * Connection conn = DriverManager.getConnection("jdbc:apache:commons:dbcp:example");
+ * </pre>
+ */
+package org.apache.tomcat.dbcp.dbcp2;