connectionproviderfactory.java

用Java实现的23个常用设计模式源代码

//$Id: ConnectionProviderFactory.java,v 1.9.2.4 2003/10/29 02:00:51 oneovthafew Exp $
package net.sf.hibernate.connection;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Properties;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import net.sf.hibernate.HibernateException;
import net.sf.hibernate.cfg.Environment;
import net.sf.hibernate.util.ReflectHelper;

/**
 * Instantiates a connection provider given either <tt>System</tt> properties or
 * a <tt>java.util.Properties</tt> instance. The <tt>ConnectionProviderFactory</tt>
 * first attempts to find a name of a <tt>ConnectionProvider</tt> subclass in the
 * property <tt>hibernate.connection.provider_class</tt>. If missing, heuristics are used
 * to choose either <tt>DriverManagerConnectionProvider</tt>,
 * <tt>DatasourceConnectionProvider</tt>, <tt>C3P0ConnectionProvider</tt> or
 * <tt>DBCPConnectionProvider</tt>.
 * @see ConnectionProvider
 * @author Gavin King
 */

public final class ConnectionProviderFactory {
	
	private static final Log log = LogFactory.getLog(ConnectionProviderFactory.class);
	
	/**
	 * Instantiate a <tt>ConnectionProvider</tt> using <tt>System</tt> properties.
	 * @return ConnectionProvider
	 * @throws HibernateException
	 */
	public static ConnectionProvider newConnectionProvider() throws HibernateException {
		return newConnectionProvider( Environment.getProperties() );
	}
	
	/**
	 * Instantiate a <tt>ConnectionProvider</tt> using given properties.
	 * Method newConnectionProvider.
	 * @param properties hibernate <tt>SessionFactory</tt> properties
	 * @return ConnectionProvider
	 * @throws HibernateException
	 */
	public static ConnectionProvider newConnectionProvider(Properties properties) throws HibernateException {
		ConnectionProvider connections;
		String providerClass = properties.getProperty(Environment.CONNECTION_PROVIDER);
		if ( providerClass!=null ) {
			try {
				log.info("Initializing connection provider: " + providerClass);
				connections = (ConnectionProvider) ReflectHelper.classForName(providerClass).newInstance();
			}
			catch (Exception e) {
				log.fatal("Could not instantiate connection provider", e);
				throw new HibernateException("Could not instantiate connection provider: " + providerClass);
			}
		}
		else if ( properties.getProperty(Environment.DATASOURCE)!=null ) {
			connections = new DatasourceConnectionProvider();
		}
		else if ( properties.getProperty(Environment.C3P0_MAX_SIZE)!=null ) {
			connections = new C3P0ConnectionProvider();
		}
		else if ( properties.getProperty(Environment.DBCP_MAXACTIVE)!=null ) {
			connections = new DBCPConnectionProvider();
		}
		else if ( 
			properties.getProperty(Environment.PROXOOL_XML)!=null ||
			properties.getProperty(Environment.PROXOOL_PROPERTIES)!=null || 
			properties.getProperty(Environment.PROXOOL_EXISTING_POOL)!=null 
		) {
			connections = new ProxoolConnectionProvider();
		}
		else if ( properties.getProperty(Environment.URL)!=null ) {
			connections = new DriverManagerConnectionProvider();
		}
		else {
			connections = new UserSuppliedConnectionProvider();
		}
		connections.configure(properties);
		return connections;
	}
	
	// cannot be instantiated
	private ConnectionProviderFactory() { throw new UnsupportedOperationException(); }
	
	/**
	 * Transform JDBC connection properties.
	 *
	 * Passed in the form <tt>hibernate.connection.*</tt> to the
	 * format accepted by <tt>DriverManager</tt> by triming the leading "<tt>hibernate.connection</tt>".
	 */
	public static Properties getConnectionProperties(Properties properties) {
		
		Iterator iter = properties.keySet().iterator();
		Properties result = new Properties();
		while ( iter.hasNext() ) {
			String prop = (String) iter.next();
			if ( prop.indexOf(Environment.CONNECTION_PREFIX) > -1 && !SPECIAL_PROPERTIES.contains(prop) ) {
				result.setProperty(
					prop.substring( Environment.CONNECTION_PREFIX.length()+1 ),
					properties.getProperty(prop)
				);
			}
		}
		String userName = properties.getProperty(Environment.USER);
		if (userName!=null) result.setProperty( "user", userName );
		return result;
	}
	
	private static final Set SPECIAL_PROPERTIES;
	static {
		SPECIAL_PROPERTIES = new HashSet();
		SPECIAL_PROPERTIES.add(Environment.DATASOURCE);
		SPECIAL_PROPERTIES.add(Environment.URL);
		SPECIAL_PROPERTIES.add(Environment.CONNECTION_PROVIDER);
		SPECIAL_PROPERTIES.add(Environment.POOL_SIZE);
		SPECIAL_PROPERTIES.add(Environment.ISOLATION);
		SPECIAL_PROPERTIES.add(Environment.DRIVER);
		SPECIAL_PROPERTIES.add(Environment.USER);
		
	}
	
}