org.apache.commons.digester3.FactoryCreateRule Maven / Gradle / Ivy
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package org.apache.commons.digester3;
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
import static java.lang.String.format;
import java.util.Formatter;
import java.util.Stack;
import org.xml.sax.Attributes;
/**
*
* Rule implementation that uses an {@link ObjectCreationFactory} to create a new object which it pushes onto the object
* stack. When the element is complete, the object will be popped.
*
*
* This rule is intended in situations where the element's attributes are needed before the object can be created. A
* common senario is for the ObjectCreationFactory implementation to use the attributes as parameters in a call to
* either a factory method or to a non-empty constructor.
*/
public class FactoryCreateRule
extends Rule
{
// ----------------------------------------------------------- Fields
/** Should exceptions thrown by the factory be ignored? */
private boolean ignoreCreateExceptions;
/** Stock to manage */
private Stack exceptionIgnoredStack;
// ----------------------------------------------------------- Constructors
/**
*
* Construct a factory create rule that will use the specified class name to create an {@link ObjectCreationFactory}
* which will then be used to create an object and push it on the stack.
*
*
* Exceptions thrown during the object creation process will be propagated.
*
*
* @param className Java class name of the object creation factory class
*/
public FactoryCreateRule( String className )
{
this( className, false );
}
/**
*
* Construct a factory create rule that will use the specified class to create an {@link ObjectCreationFactory}
* which will then be used to create an object and push it on the stack.
*
*
* Exceptions thrown during the object creation process will be propagated.
*
*
* @param clazz Java class name of the object creation factory class
*/
public FactoryCreateRule( Class> clazz )
{
this( clazz, false );
}
/**
*
* Construct a factory create rule that will use the specified class name (possibly overridden by the specified
* attribute if present) to create an {@link ObjectCreationFactory}, which will then be used to instantiate an
* object instance and push it onto the stack.
*
*
* Exceptions thrown during the object creation process will be propagated.
*
*
* @param className Default Java class name of the factory class
* @param attributeName Attribute name which, if present, contains an override of the class name of the object
* creation factory to create.
*/
public FactoryCreateRule( String className, String attributeName )
{
this( className, attributeName, false );
}
/**
*
* Construct a factory create rule that will use the specified class (possibly overridden by the specified attribute
* if present) to create an {@link ObjectCreationFactory}, which will then be used to instantiate an object instance
* and push it onto the stack.
*
*
* Exceptions thrown during the object creation process will be propagated.
*
*
* @param clazz Default Java class name of the factory class
* @param attributeName Attribute name which, if present, contains an override of the class name of the object
* creation factory to create.
*/
public FactoryCreateRule( Class> clazz, String attributeName )
{
this( clazz, attributeName, false );
}
/**
*
* Construct a factory create rule using the given, already instantiated, {@link ObjectCreationFactory}.
*
*
* Exceptions thrown during the object creation process will be propagated.
*
*
* @param creationFactory called on to create the object.
*/
public FactoryCreateRule( ObjectCreationFactory creationFactory )
{
this( creationFactory, false );
}
/**
* Construct a factory create rule that will use the specified class name to create an {@link ObjectCreationFactory}
* which will then be used to create an object and push it on the stack.
*
* @param className Java class name of the object creation factory class
* @param ignoreCreateExceptions if true, exceptions thrown by the object creation factory will be ignored.
*/
public FactoryCreateRule( String className, boolean ignoreCreateExceptions )
{
this( className, null, ignoreCreateExceptions );
}
/**
* Construct a factory create rule that will use the specified class to create an {@link ObjectCreationFactory}
* which will then be used to create an object and push it on the stack.
*
* @param clazz Java class name of the object creation factory class
* @param ignoreCreateExceptions if true, exceptions thrown by the object creation factory will be ignored.
*/
public FactoryCreateRule( Class> clazz, boolean ignoreCreateExceptions )
{
this( clazz, null, ignoreCreateExceptions );
}
/**
* Construct a factory create rule that will use the specified class name (possibly overridden by the specified
* attribute if present) to create an {@link ObjectCreationFactory}, which will then be used to instantiate an
* object instance and push it onto the stack.
*
* @param className Default Java class name of the factory class
* @param attributeName Attribute name which, if present, contains an override of the class name of the object
* creation factory to create.
* @param ignoreCreateExceptions if true, exceptions thrown by the object creation factory will be ignored.
*/
public FactoryCreateRule( String className, String attributeName, boolean ignoreCreateExceptions )
{
this.className = className;
this.attributeName = attributeName;
this.ignoreCreateExceptions = ignoreCreateExceptions;
}
/**
* Construct a factory create rule that will use the specified class (possibly overridden by the specified attribute
* if present) to create an {@link ObjectCreationFactory}, which will then be used to instantiate an object instance
* and push it onto the stack.
*
* @param clazz Default Java class name of the factory class
* @param attributeName Attribute name which, if present, contains an override of the class name of the object
* creation factory to create.
* @param ignoreCreateExceptions if true, exceptions thrown by the object creation factory will be ignored.
*/
public FactoryCreateRule( Class> clazz, String attributeName,
boolean ignoreCreateExceptions )
{
this( clazz.getName(), attributeName, ignoreCreateExceptions );
}
/**
* Construct a factory create rule using the given, already instantiated, {@link ObjectCreationFactory}.
*
* @param creationFactory called on to create the object.
* @param ignoreCreateExceptions if true, exceptions thrown by the object creation factory will be ignored.
*/
public FactoryCreateRule( ObjectCreationFactory creationFactory, boolean ignoreCreateExceptions )
{
this.creationFactory = creationFactory;
this.ignoreCreateExceptions = ignoreCreateExceptions;
}
// ----------------------------------------------------- Instance Variables
/**
* The attribute containing an override class name if it is present.
*/
protected String attributeName = null;
/**
* The Java class name of the ObjectCreationFactory to be created. This class must have a no-arguments constructor.
*/
protected String className = null;
/**
* The object creation factory we will use to instantiate objects as required based on the attributes specified in
* the matched XML element.
*/
protected ObjectCreationFactory creationFactory = null;
// --------------------------------------------------------- Public Methods
/**
* {@inheritDoc}
*/
@Override
public void begin( String namespace, String name, Attributes attributes )
throws Exception
{
if ( ignoreCreateExceptions )
{
if ( exceptionIgnoredStack == null )
{
exceptionIgnoredStack = new Stack();
}
try
{
Object instance = getFactory( attributes ).createObject( attributes );
if ( getDigester().getLogger().isDebugEnabled() )
{
getDigester().getLogger().debug( format( "[FactoryCreateRule]{%s} New %s",
getDigester().getMatch(),
( instance == null ? "null object"
: instance.getClass().getName() ) ) );
}
getDigester().push( instance );
exceptionIgnoredStack.push( Boolean.FALSE );
}
catch ( Exception e )
{
// log message and error
if ( getDigester().getLogger().isInfoEnabled() )
{
getDigester().getLogger().info( format( "[FactoryCreateRule]{%s} Create exception ignored: %s",
getDigester().getMatch(),
( ( e.getMessage() == null ) ? e.getClass().getName()
: e.getMessage() ) ) );
if ( getDigester().getLogger().isDebugEnabled() )
{
getDigester().getLogger().debug( "[FactoryCreateRule] Ignored exception:", e );
}
}
exceptionIgnoredStack.push( Boolean.TRUE );
}
}
else
{
Object instance = getFactory( attributes ).createObject( attributes );
if ( getDigester().getLogger().isDebugEnabled() )
{
getDigester().getLogger().debug( format( "[FactoryCreateRule]{%s} New %s",
getDigester().getMatch(),
( instance == null ? "null object"
: instance.getClass().getName() ) ) );
}
getDigester().push( instance );
}
}
/**
* {@inheritDoc}
*/
@Override
public void end( String namespace, String name )
throws Exception
{
// check if object was created
// this only happens if an exception was thrown and we're ignoring them
if ( ignoreCreateExceptions
&& exceptionIgnoredStack != null
&& !exceptionIgnoredStack.empty()
&& exceptionIgnoredStack.pop().booleanValue() )
{
// creation exception was ignored
// nothing was put onto the stack
if ( getDigester().getLogger().isTraceEnabled() )
{
getDigester().getLogger().trace( format( "[FactoryCreateRule]{%s} No creation so no push so no pop",
getDigester().getMatch() ) );
}
return;
}
Object top = getDigester().pop();
if ( getDigester().getLogger().isDebugEnabled() )
{
getDigester().getLogger().debug( format( "[FactoryCreateRule]{%s} Pop %s",
getDigester().getMatch(),
top.getClass().getName() ) );
}
}
/**
* {@inheritDoc}
*/
@Override
public void finish()
throws Exception
{
if ( attributeName != null )
{
creationFactory = null;
}
}
/**
* {@inheritDoc}
*/
@Override
public String toString()
{
Formatter formatter = new Formatter().format( "FactoryCreateRule[className=%s, attributeName=%s",
className, attributeName );
if ( creationFactory != null )
{
formatter.format( ", creationFactory=%s", creationFactory );
}
formatter.format( "]" );
return ( formatter.toString() );
}
// ------------------------------------------------------ Protected Methods
/**
* Return an instance of our associated object creation factory, creating one if necessary.
*
* @param attributes Attributes passed to our factory creation element
* @return An instance of our associated object creation factory, creating one if necessary
* @exception Exception if any error occurs
*/
protected ObjectCreationFactory getFactory( Attributes attributes )
throws Exception
{
if ( creationFactory == null )
{
String realClassName = className;
if ( attributeName != null )
{
String value = attributes.getValue( attributeName );
if ( value != null )
{
realClassName = value;
}
}
if ( getDigester().getLogger().isDebugEnabled() )
{
getDigester().getLogger().debug( format( "[FactoryCreateRule]{%s} New factory %s",
getDigester().getMatch(), realClassName ) );
}
Class clazz = getDigester().getClassLoader().loadClass( realClassName );
creationFactory = (ObjectCreationFactory) clazz.newInstance();
creationFactory.setDigester( getDigester() );
}
return ( creationFactory );
}
}