attrib4j
Class AttributeFactory

java.lang.Object
  |
  +--attrib4j.AttributeFactory

Direct Known Subclasses:

BCELFactory, CFParseFactory

public abstract class AttributeFactory

extends java.lang.Object

Factory for creating ClassAnnotator and AttributeExtractor instances, with discovery and configuration features similar to that employed by standard Java APIs such as JAXP. Current implementations are based on IBM CFParse and Jakarta's BCEL bytecode manipulation libraries.

Note:These classes are not used by client code. The factory does not create 'Attribute' instances. Attributes can be any serializable class and are independent of which bytecode manipulation library is used.

Implementation taken from the jakarata commons logging package.

Version:

$Revision: 1.5 $ $Date: 2003/04/10 03:36:16 $

Author:

Mark Pollack

Field Summary

protected static java.util.Hashtable	factories The previously constructed AttributeFactory instances, keyed by the ClassLoader with which it was created.
static java.lang.String	FACTORY_DEFAULT The fully qualified class name of the fallback AttributeFactory implementation class to use, if no other can be found.
static java.lang.String	FACTORY_PROPERTIES The name of the properties file to search for.
static java.lang.String	FACTORY_PROPERTY The name of the property used to identify the AttributeFactory implementation class name.
protected static java.lang.String	SERVICE_ID JDK1.3+ 'Service Provider' specification ( http://java.sun.com/j2se/1.3/docs/guide/jar/jar.html )

Constructor Summary

protected

AttributeFactory() Protected constructor that is not available for public use.

Method Summary

abstract AttributeExtractor	getAttributeExtractor() Method to return a AttributeExtractor.
abstract ClassAnnotator	getClassAnnotator(java.io.InputStream is, java.lang.String classfileName) Method to return a ClassAnnotator.
protected static java.lang.ClassLoader	getContextClassLoader() Return the thread context class loader if available.
static AttributeFactory	getFactory() Construct (if necessary) and return a AttributeFactory instance, using the following ordered lookup procedure to determine the name of the implementation class to be loaded.
protected static AttributeFactory	newFactory(java.lang.String factoryClass, java.lang.ClassLoader classLoader) Return a new instance of the specified AttributeFactory implementation class, loaded by the specified class loader.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

FACTORY_PROPERTY

public static final java.lang.String FACTORY_PROPERTY

The name of the property used to identify the AttributeFactory implementation class name.

See Also:

Constant Field Values

FACTORY_DEFAULT

public static final java.lang.String FACTORY_DEFAULT

The fully qualified class name of the fallback AttributeFactory implementation class to use, if no other can be found.

See Also:

Constant Field Values

FACTORY_PROPERTIES

public static final java.lang.String FACTORY_PROPERTIES

The name of the properties file to search for.

See Also:

Constant Field Values

SERVICE_ID

protected static final java.lang.String SERVICE_ID

JDK1.3+ 'Service Provider' specification ( http://java.sun.com/j2se/1.3/docs/guide/jar/jar.html )

See Also:

Constant Field Values

factories

protected static java.util.Hashtable factories

The previously constructed AttributeFactory instances, keyed by the ClassLoader with which it was created.

Constructor Detail

AttributeFactory

protected AttributeFactory()

Protected constructor that is not available for public use.

Method Detail

getFactory

public static AttributeFactory getFactory()
                                   throws AttributeException

Construct (if necessary) and return a AttributeFactory instance, using the following ordered lookup procedure to determine the name of the implementation class to be loaded.

• The attrib4j.AttributeFactory system property.
• The JDK 1.3 Service Discovery mechanism
• Use the properties file attrib4j.properties file, if found in the class path of this class. The configuration file is in standard java.util.Properties format and contains the fully qualified name of the implementation class with the key being the system property defined above.
• Fall back to a default implementation class (attrib4j.bcel.BCELFactory).

Throws:

AttributeException - if the implementation class is not available or cannot be instantiated.

getAttributeExtractor

public abstract AttributeExtractor getAttributeExtractor()
                                                  throws AttributeException

Method to return a AttributeExtractor.

Throws:

AttributeException - if a suitable AttributeExtractor instance cannot be returned

getClassAnnotator

public abstract ClassAnnotator getClassAnnotator(java.io.InputStream is,
                                                 java.lang.String classfileName)
                                          throws AttributeException

Method to return a ClassAnnotator.

Parameters:

classfileName - the name of the .class file.

Returns:

a value of type 'ClassAnnotator'

Throws:

AttributeException - if a suitable AttributeFactor instance cannot be returned

getContextClassLoader

protected static java.lang.ClassLoader getContextClassLoader()
                                                      throws AttributeException

Return the thread context class loader if available. Otherwise return null. The thread context class loader is available for JDK 1.2 or later, if certain security conditions are met.

Throws:

AttributeException - if a suitable class loader cannot be identified.

newFactory

protected static AttributeFactory newFactory(java.lang.String factoryClass,
                                             java.lang.ClassLoader classLoader)
                                      throws AttributeException

Return a new instance of the specified AttributeFactory implementation class, loaded by the specified class loader. If that fails, try the class loader used to load this (abstract) AttributeFactory.

Parameters:

factoryClass - Fully qualified name of the AttributeFactory implementation class

classLoader - ClassLoader from which to load this class

Throws:

AttributeException - if a suitable instance cannot be created