public static TwoWayFieldBridge extractTwoWayType(FieldBridge fieldBridge) 
{
		FieldBridge fb = extractType( fieldBridge );
		if ( fb instanceof TwoWayFieldBridge ) {
			return ( TwoWayFieldBridge ) fb;
		}
		else {
			throw new SearchException( "FieldBridge passed in is not an instance of " + TwoWayFieldBridge.class.getSimpleName() );
		}
}

Takes in a fieldBridge and will return you a TwoWayFieldBridge instance.

 public static FieldBridge extractType(ClassBridge cb) 
{
	 
		builtInBridges.put( Double.class.getName(), DOUBLE );
		builtInBridges.put( double.class.getName(), DOUBLE );
		builtInBridges.put( Float.class.getName(), FLOAT );
		builtInBridges.put( float.class.getName(), FLOAT );
		builtInBridges.put( Short.class.getName(), SHORT );
		builtInBridges.put( short.class.getName(), SHORT );
		builtInBridges.put( Integer.class.getName(), INTEGER );
		builtInBridges.put( int.class.getName(), INTEGER );
		builtInBridges.put( Long.class.getName(), LONG );
		builtInBridges.put( long.class.getName(), LONG );
		builtInBridges.put( BigInteger.class.getName(), BIG_INTEGER );
		builtInBridges.put( BigDecimal.class.getName(), BIG_DECIMAL );
		builtInBridges.put( String.class.getName(), STRING );
		builtInBridges.put( Boolean.class.getName(), BOOLEAN );
		builtInBridges.put( boolean.class.getName(), BOOLEAN );
		builtInBridges.put( Class.class.getName(), CLAZZ );
		builtInBridges.put( URL.class.getName(), Url );
		builtInBridges.put( URI.class.getName(), Uri );
		builtInBridges.put( Date.class.getName(), DATE_MILLISECOND );
		FieldBridge bridge = null;
		if ( cb != null ) {
			Class impl = cb.impl();
			//TODO better error information ( see guessType() )
			if (impl != null) {
				try {
					Object instance = impl.newInstance();
					if ( FieldBridge.class.isAssignableFrom( impl ) ) {
						bridge = (FieldBridge) instance;
					}
					else if ( org.hibernate.search.bridge.TwoWayStringBridge.class.isAssignableFrom( impl ) ) {
						bridge = new TwoWayString2FieldBridgeAdaptor(
								(org.hibernate.search.bridge.TwoWayStringBridge) instance );
					}
					else if ( org.hibernate.search.bridge.StringBridge.class.isAssignableFrom( impl ) ) {
						bridge = new String2FieldBridgeAdaptor( (org.hibernate.search.bridge.StringBridge) instance );
					}
					else {
						throw new SearchException("@ClassBridge implementation implements none of the field bridge interfaces: "
								+ impl );
					}
					if ( cb.params().length  > 0 && ParameterizedBridge.class.isAssignableFrom( impl ) ) {
						Map params = new HashMap( cb.params().length );
						for ( Parameter param : cb.params() ) {
							params.put( param.name(), param.value() );
						}
						( (ParameterizedBridge) instance ).setParameterValues( params );
					}
				}
				catch (Exception e) {
					throw new HibernateException( "Unable to instantiate FieldBridge for " + ClassBridge.class.getName(), e );
				}
			}
		}
		if ( bridge == null ) throw new SearchException( "Unable to guess FieldBridge for " + ClassBridge.class.getName() );
		return bridge;
}

This extracts and instantiates the implementation class from a ClassBridge annotation.

 public static FieldBridge extractType(FieldBridge fieldBridgeAnnotation) 
{
		FieldBridge bridge = null;
		if ( fieldBridgeAnnotation != null ) {
			bridge = doExtractType( fieldBridgeAnnotation, null );
		}
		if ( bridge == null ) {
			throw new SearchException(
					"Unable to guess FieldBridge for " + org.hibernate.search.annotations.FieldBridge.class.getName()
			);
		}
		return bridge;
}

This extracts and instantiates the implementation class from a ClassBridge annotation.

 public static FieldBridge getDateField(Resolution resolution) 
{
		switch (resolution) {
			case YEAR:
				return DATE_YEAR;
			case MONTH:
				return DATE_MONTH;
			case DAY:
				return DATE_DAY;
			case HOUR:
				return DATE_HOUR;
			case MINUTE:
				return DATE_MINUTE;
			case SECOND:
				return DATE_SECOND;
			case MILLISECOND:
				return DATE_MILLISECOND;
			default:
				throw new AssertionFailure( "Unknown Resolution: " + resolution );
		}
}

 public static FieldBridge guessType(Field field,
    XMember member,
    ReflectionManager reflectionManager) 
{
		FieldBridge bridge;
		org.hibernate.search.annotations.FieldBridge bridgeAnn;
		//@Field bridge has priority over @FieldBridge
		if ( field != null && void.class != field.bridge().impl() ) {
			bridgeAnn = field.bridge();
		}
		else {
			bridgeAnn = member.getAnnotation( org.hibernate.search.annotations.FieldBridge.class );
		}
		final String memberName = member.getName();
		if ( bridgeAnn != null ) {
			bridge = doExtractType( bridgeAnn, memberName );
		}
		else if ( member.isAnnotationPresent( org.hibernate.search.annotations.DateBridge.class ) ) {
			Resolution resolution =
					member.getAnnotation( org.hibernate.search.annotations.DateBridge.class ).resolution();
			bridge = getDateField( resolution );
		}
		else {
			//find in built-ins
			XClass returnType = member.getType();
			bridge = builtInBridges.get( returnType.getName() );
			if ( bridge == null && returnType.isEnum() ) {
				bridge = new TwoWayString2FieldBridgeAdaptor(
						new EnumBridge( (Class< ? extends Enum >) reflectionManager.toClass( returnType ) )
				);
			}
		}
		//TODO add classname
		if ( bridge == null ) throw new SearchException( "Unable to guess FieldBridge for " + memberName );
		return bridge;
}