Java DBCP 连接池(三)

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* http://www.apache.org/licenses/LICENSE-2.0
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import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.ResultSet;
import java.sql.SQLException;
//
// Here are the dbcp-specific classes.
// Note that they are only used in the setupDriver
// method. In normal use, your classes interact
// only with the standard JDBC API
//
import org.apache.commons.pool.ObjectPool;
import org.apache.commons.pool.impl.GenericObjectPool;
import org.apache.commons.dbcp.ConnectionFactory;
import org.apache.commons.dbcp.PoolingDriver;
import org.apache.commons.dbcp.PoolableConnectionFactory;
import org.apache.commons.dbcp.DriverManagerConnectionFactory;
//
// Here's a simple example of how to use the PoolingDriver.
// In this example, we'll construct the PoolingDriver manually,
// just to show how the pieces fit together, but you could also
// configure it using an external conifguration file in
// JOCL format (and eventually Digester).
//
//
// To compile this example, you'll want:
// * commons-pool-1.3.jar
// * commons-dbcp-1.2.2.jar
// in your classpath.
//
// To run this example, you'll want:
// * commons-collections.jar
// * commons-pool-1.3.jar
// * commons-dbcp-1.2.2.jar
// * the classes for your (underlying) JDBC driver
// in your classpath.
//
// Invoke the class using two arguments:
// * the connect string for your underlying JDBC driver
// * the query you'd like to execute
// You'll also want to ensure your underlying JDBC driver
// is registered. You can use the "jdbc.drivers"
// property to do this.
//
// For example:
// java -Djdbc.drivers=oracle.jdbc.driver.OracleDriver \
// -classpath commons-pool-1.3.jar:commons-dbcp-1.2.2.jar:oracle-jdbc.jar:. \
// ManualPoolingDriverExample
// "jdbc:oracle:thin:scott/tiger@myhost:1521:mysid"
// "SELECT * FROM DUAL"
//
public class ManualPoolingDriverExample {
public static void main(String[] args) {
//
// First we load the underlying JDBC driver.
// You need this if you don't use the jdbc.drivers
// system property.
//
System.out.println("Loading underlying JDBC driver.");
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
System.out.println("Done.");
//
// Then we set up and register the PoolingDriver.
// Normally this would be handled auto-magically by
// an external configuration, but in this example we'll
// do it manually.
//
System.out.println("Setting up driver.");
try {
setupDriver(args[0]);
} catch (Exception e) {
e.printStackTrace();
}
System.out.println("Done.");
//
// Now, we can use JDBC as we normally would.
// Using the connect string
// jdbc:apache:commons:dbcp:example
// The general form being:
// jdbc:apache:commons:dbcp:<name-of-pool>
//
Connection conn = null;
Statement stmt = null;
ResultSet rset = null;
try {
System.out.println("Creating connection.");
conn = DriverManager.getConnection("jdbc:apache:commons:dbcp:example");
System.out.println("Creating statement.");
stmt = conn.createStatement();
System.out.println("Executing statement.");
rset = stmt.executeQuery(args[1]);
System.out.println("Results:");
int numcols = rset.getMetaData().getColumnCount();
while(rset.next()) {
for(int i=1;i<=numcols;i++) {
System.out.print("\t" + rset.getString(i));
}
System.out.println("");
}
} catch(SQLException e) {
e.printStackTrace();
} finally {
try { rset.close(); } catch(Exception e) { }
try { stmt.close(); } catch(Exception e) { }
try { conn.close(); } catch(Exception e) { }
}
// Display some pool statistics
try {
printDriverStats();
} catch (Exception e) {
e.printStackTrace();
}
// closes the pool
try {
shutdownDriver();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void setupDriver(String connectURI) throws Exception {
//
// First, we'll need a ObjectPool that serves as the
// actual pool of connections.
//
// We'll use a GenericObjectPool instance, although
// any ObjectPool implementation will suffice.
//
ObjectPool connectionPool = new GenericObjectPool(null);
//
// Next, we'll create a ConnectionFactory that the
// pool will use to create Connections.
// We'll use the DriverManagerConnectionFactory,
// using the connect string passed in the command line
// arguments.
//
ConnectionFactory connectionFactory = new DriverManagerConnectionFactory(connectURI,null);
//
// Now we'll create the PoolableConnectionFactory, which wraps
// the "real" Connections created by the ConnectionFactory with
// the classes that implement the pooling functionality.
//
PoolableConnectionFactory poolableConnectionFactory = new PoolableConnectionFactory(connectionFactory,connectionPool,null,null,false,true);
//
// Finally, we create the PoolingDriver itself...
//
Class.forName("org.apache.commons.dbcp.PoolingDriver");
PoolingDriver driver = (PoolingDriver) DriverManager.getDriver("jdbc:apache:commons:dbcp:");
//
// ...and register our pool with it.
//
driver.registerPool("example",connectionPool);
//
// Now we can just use the connect string "jdbc:apache:commons:dbcp:example"
// to access our pool of Connections.
//
}
public static void printDriverStats() throws Exception {
PoolingDriver driver = (PoolingDriver) DriverManager.getDriver("jdbc:apache:commons:dbcp:");
ObjectPool connectionPool = driver.getConnectionPool("example");

System.out.println("NumActive: " + connectionPool.getNumActive());
System.out.println("NumIdle: " + connectionPool.getNumIdle());
}
public static void shutdownDriver() throws Exception {
PoolingDriver driver = (PoolingDriver) DriverManager.getDriver("jdbc:apache:commons:dbcp:");
driver.closePool("example");
}
}