在数据库连接池 编程里使用了copyonwritearrayList

@Override
	public void config(ComponentConfig config)
	{
		super.config(config);

		// use the security handler to retrieve password
		// if it is available.
		if (securityHandler == null) {
			securityHandler = ContextManager.getSecurityHandler();
		}
		if (securityHandler != null) {
			password = securityHandler.retrievePassword(keyHost, user);
		}

		try {
			dataSource = new OracleConnectionPoolDataSource();
			Properties properties = CommonUtil.retrieveStringProperties(systemProperties);;
			// process id as current pid
			properties.setProperty("oracle.jdbc.v$session.process", String.valueOf(CommonUtil.getPid()));
			properties.setProperty("oracle.jdbc.ReadTimeout", String.valueOf(readTimeout * 1000));
			properties.setProperty("oracle.net.disableOob", String.valueOf(oracleNetDisableOob));
			dataSource.setConnectionProperties(properties);
			
			//dataSource.setDriverClass("oracle.jdbc.OracleDriver");
			dataSource.setURL(brokerUrl);
			dataSource.setUser(user);
			dataSource.setPassword(password);

			// the settings below are optional -- c3p0 can work with defaults
			//dataSource.setMinPoolSize(initialPoolSize);
			//dataSource.setMaxPoolSize(maxPoolSize);
			//dataSource.setAcquireIncrement(this.aquireIncrement);

			connectionFactory = AQjmsFactory.getConnectionFactory(dataSource);
			connections = new CopyOnWriteArrayList<JmsConnection>();
			createConnections(this.initialPoolSize);
			LOGGER.debug(String.format(
					"connection pool initialized with %d connections",
					initialPoolSize));
		}
		catch (JMSException e) {
			String error = "Failed to get connectionFactory with error "
					+ e.getMessage();
			LOGGER.error(error);
			throw new InitializationException(error);
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		LOGGER.debug(String.format(
				"connection pool initialized with %d connections",
				initialPoolSize));
		// replace cxCode for OracleAQ
		if (DEFAULT_JMS_CX_CODE.equals(cxCode)) {
			cxCode = "CX610";
		}
	}