/*
* Copyright 2001-2004 The Apache Software Foundation.
*
* Licensed 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.
*/
package org.apache.commons.betwixt.io;
import java.beans.IntrospectionException;
import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import org.apache.commons.betwixt.AttributeDescriptor;
import org.apache.commons.betwixt.BindingConfiguration;
import org.apache.commons.betwixt.Descriptor;
import org.apache.commons.betwixt.ElementDescriptor;
import org.apache.commons.betwixt.XMLBeanInfo;
import org.apache.commons.betwixt.XMLIntrospector;
import org.apache.commons.betwixt.digester.XMLIntrospectorHelper;
import org.apache.commons.betwixt.expression.Context;
import org.apache.commons.betwixt.expression.Expression;
import org.apache.commons.betwixt.io.id.SequentialIDGenerator;
import org.apache.commons.collections.ArrayStack;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;
// FIX ME!!!
// Logging logic!
// FIX ME!!
// Error handling strategy!
// i'm going to add SAXExceptions everywhere since it's the easiest way to make things work quick
// but this is a poor strategy
/**
* <p>Abstract superclass for bean writers.
* This class encapsulates the processing logic.
* Subclasses provide implementations for the actual expression of the xml.</p>
* <h5>SAX Inspired Writing API</h5>
* <p>
* This class is intended to be used by subclassing:
* concrete subclasses perform the actual writing by providing
* suitable implementations for the following methods inspired
* by <a href='http://www.saxproject.org'>SAX</a>:
* </p>
* <ul>
* <li> {@link #start} - called when processing begins</li>
* <li> {@link #startElement(WriteContext, String, String, String, Attributes)}
* - called when the start of an element
* should be written</li>
* <li> {@link #bodyText(WriteContext, String)}
* - called when the start of an element
* should be written</li>
* <li> {@link #endElement(WriteContext, String, String, String)}
* - called when the end of an element
* should be written</li>
* <li> {@link #end} - called when processing has been completed</li>
* </ul>
* <p>
* <strong>Note</strong> that this class contains many deprecated
* versions of the writing API. These will be removed soon so care
* should be taken to use the latest version.
* </p>
* <p>
* <strong>Note</strong> that this class is designed to be used
* in a single threaded environment. When used in multi-threaded
* environments, use of a common <code>XMLIntrospector</code>
* and pooled writer instances should be considered.
* </p>
*
* @author <a href="mailto:rdonkin@apache.org">Robert Burrell Donkin</a>
* @version $Revision: 1.26.2.1 $
*/
public abstract class AbstractBeanWriter {
/** Introspector used */
private XMLIntrospector introspector = new XMLIntrospector();
/** Log used for logging (Doh!) */
private Log log = LogFactory.getLog( AbstractBeanWriter.class );
/** Map containing ID attribute values for beans */
private HashMap idMap = new HashMap();
/** Stack containing beans - used to detect cycles */
private ArrayStack beanStack = new ArrayStack();
/** Used to generate ID attribute values*/
private IDGenerator idGenerator = new SequentialIDGenerator();
/** Should empty elements be written out? */
private boolean writeEmptyElements = true;
/** Dynamic binding configuration settings */
private BindingConfiguration bindingConfiguration = new BindingConfiguration();
/** <code>WriteContext</code> implementation reused curing writing */
private WriteContextImpl writeContext = new WriteContextImpl();
/**
* Marks the start of the bean writing.
* By default doesn't do anything, but can be used
* to do extra start processing
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
*/
public void start() throws IOException, SAXException {
}
/**
* Marks the start of the bean writing.
* By default doesn't do anything, but can be used
* to do extra end processing
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
*/
public void end() throws IOException, SAXException {
}
/**
* <p> Writes the given bean to the current stream using the XML introspector.</p>
*
* <p> This writes an xml fragment representing the bean to the current stream.</p>
*
* <p>This method will throw a <code>CyclicReferenceException</code> when a cycle
* is encountered in the graph <strong>only</strong> if the <code>getMapIDs()</code>
* setting of the </code>BindingConfiguration</code> is false.</p>
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
*
* @param bean write out representation of this bean
*/
public void write(Object bean) throws
IOException,
SAXException,
IntrospectionException {
if (log.isDebugEnabled()) {
log.debug( "Writing bean graph..." );
log.debug( bean );
}
start();
write( null, bean );
end();
if (log.isDebugEnabled()) {
log.debug( "Finished writing bean graph." );
}
}
/**
* <p>Writes the given bean to the current stream
* using the given <code>qualifiedName</code>.</p>
*
* <p>This method will throw a <code>CyclicReferenceException</code> when a cycle
* is encountered in the graph <strong>only</strong> if the <code>getMapIDs()</code>
* setting of the <code>BindingConfiguration</code> is false.</p>
*
* @param qualifiedName the string naming root element
* @param bean the <code>Object</code> to write out as xml
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
*/
public void write(
String qualifiedName,
Object bean)
throws
IOException,
SAXException,
IntrospectionException {
writeBean( "", qualifiedName, qualifiedName, bean, makeContext( bean ) );
}
/**
* <p>Writes the given bean to the current stream
* using the given <code>qualifiedName</code>.</p>
*
* <p>This method will throw a <code>CyclicReferenceException</code> when a cycle
* is encountered in the graph <strong>only</strong> if the <code>getMapIDs()</code>
* setting of the <code>BindingConfiguration</code> is false.</p>
*
* @param namespaceUri the namespace uri
* @param localName the local name
* @param qualifiedName the string naming root element
* @param bean the <code>Object</code> to write out as xml
* @param context not null
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
*/
private void writeBean (
String namespaceUri,
String localName,
String qualifiedName,
Object bean,
Context context)
throws
IOException,
SAXException,
IntrospectionException {
if ( log.isTraceEnabled() ) {
log.trace( "Writing bean graph (qualified name '" + qualifiedName + "'" );
}
// introspect to obtain bean info
XMLBeanInfo beanInfo = introspector.introspect( bean );
if ( beanInfo != null ) {
ElementDescriptor elementDescriptor = beanInfo.getElementDescriptor();
if ( elementDescriptor != null ) {
context = context.newContext( bean );
if ( qualifiedName == null ) {
qualifiedName = elementDescriptor.getQualifiedName();
}
if ( namespaceUri == null ) {
namespaceUri = elementDescriptor.getURI();
}
if ( localName == null ) {
localName = elementDescriptor.getLocalName();
}
String ref = null;
String id = null;
// only give id's to non-primatives
if ( elementDescriptor.isPrimitiveType() ) {
// write without an id
writeElement(
namespaceUri,
localName,
qualifiedName,
elementDescriptor,
context );
} else {
pushBean ( context.getBean() );
if ( getBindingConfiguration().getMapIDs() ) {
ref = (String) idMap.get( context.getBean() );
}
if ( ref == null ) {
// this is the first time that this bean has be written
AttributeDescriptor idAttribute = beanInfo.getIDAttribute();
if (idAttribute == null) {
// use a generated id
id = idGenerator.nextId();
idMap.put( bean, id );
if ( getBindingConfiguration().getMapIDs() ) {
// write element with id
writeElement(
namespaceUri,
localName,
qualifiedName,
elementDescriptor,
context ,
beanInfo.getIDAttributeName(),
id);
} else {
// write element without ID
writeElement(
namespaceUri,
localName,
qualifiedName,
elementDescriptor,
context );
}
} else {
// use id from bean property
// it's up to the user to ensure uniqueness
// XXX should we trap nulls?
Object exp = idAttribute.getTextExpression().evaluate( context );
if (exp == null) {
// we'll use a random id
log.debug("Using random id");
id = idGenerator.nextId();
} else {
// convert to string
id = exp.toString();
}
idMap.put( bean, id);
// the ID attribute should be written automatically
writeElement(
namespaceUri,
localName,
qualifiedName,
elementDescriptor,
context );
}
} else {
if ( !ignoreElement( elementDescriptor, context )) {
// we've already written this bean so write an IDREF
writeIDREFElement(
elementDescriptor,
namespaceUri,
localName,
qualifiedName,
beanInfo.getIDREFAttributeName(),
ref);
}
}
popBean();
}
}
}
log.trace( "Finished writing bean graph." );
}
/**
* Get <code>IDGenerator</code> implementation used to
* generate <code>ID</code> attribute values .
*
* @return implementation used for <code>ID</code> attribute generation
*/
public IDGenerator getIdGenerator() {
return idGenerator;
}
/**
* Set <code>IDGenerator</code> implementation
* used to generate <code>ID</code> attribute values.
* This property can be used to customize the algorithm used for generation.
*
* @param idGenerator use this implementation for <code>ID</code> attribute generation
*/
public void setIdGenerator(IDGenerator idGenerator) {
this.idGenerator = idGenerator;
}
/**
* Gets the dynamic configuration setting to be used for bean reading.
* @return the BindingConfiguration settings, not null
* @since 0.5
*/
public BindingConfiguration getBindingConfiguration() {
return bindingConfiguration;
}
/**
* Sets the dynamic configuration setting to be used for bean reading.
* @param bindingConfiguration the BindingConfiguration settings, not null
* @since 0.5
*/
public void setBindingConfiguration(BindingConfiguration bindingConfiguration) {
this.bindingConfiguration = bindingConfiguration;
}
/**
* <p>Should generated <code>ID</code> attribute values be added to the elements?</p>
*
* <p>If IDs are not being written then if a cycle is encountered in the bean graph,
* then a {@link CyclicReferenceException} will be thrown by the write method.</p>
*
* @return true if <code>ID</code> and <code>IDREF</code> attributes are to be written
* @deprecated 0.5 use {@link BindingConfiguration#getMapIDs}
*/
public boolean getWriteIDs() {
return getBindingConfiguration().getMapIDs();
}
/**
* Set whether generated <code>ID</code> attribute values should be added to the elements
* If this property is set to false, then <code>CyclicReferenceException</code>
* will be thrown whenever a cyclic occurs in the bean graph.
*
* @param writeIDs true if <code>ID</code>'s and <code>IDREF</code>'s should be written
* @deprecated 0.5 use {@link BindingConfiguration#setMapIDs}
*/
public void setWriteIDs(boolean writeIDs) {
getBindingConfiguration().setMapIDs( writeIDs );
}
/**
* <p>Gets whether empty elements should be written into the output.</p>
*
* <p>An empty element is one that has no attributes, no child elements
* and no body text.
* For example, <code><element/></code> is an empty element but
* <code><element attr='value'/></code> is not.</p>
*
* @return true if empty elements will be written into the output
* @since 0.5
*/
public boolean getWriteEmptyElements() {
return writeEmptyElements;
}
/**
* <p>Sets whether empty elements should be written into the output.</p>
*
* <p>An empty element is one that has no attributes, no child elements
* and no body text.
* For example, <code><element/></code> is an empty element but
* <code><element attr='value'/></code> is not.
*
* @param writeEmptyElements true if empty elements should be written into the output
* @since 0.5
*/
public void setWriteEmptyElements(boolean writeEmptyElements) {
this.writeEmptyElements = writeEmptyElements;
}
/**
* <p>Gets the introspector used.</p>
*
* <p>The {@link XMLBeanInfo} used to map each bean is
* created by the <code>XMLIntrospector</code>.
* One way in which the mapping can be customized is
* by altering the <code>XMLIntrospector</code>. </p>
*
* @return the <code>XMLIntrospector</code> used for introspection
*/
public XMLIntrospector getXMLIntrospector() {
return introspector;
}
/**
* <p>Sets the introspector to be used.</p>
*
* <p>The {@link XMLBeanInfo} used to map each bean is
* created by the <code>XMLIntrospector</code>.
* One way in which the mapping can be customized is by
* altering the <code>XMLIntrospector</code>. </p>
*
* @param introspector use this introspector
*/
public void setXMLIntrospector(XMLIntrospector introspector) {
this.introspector = introspector;
}
/**
* <p>Gets the current logging implementation.</p>
*
* @return the <code>Log</code> implementation which this class logs to
*/
public final Log getAbstractBeanWriterLog() {
return log;
}
/**
* <p> Set the current logging implementation. </p>
*
* @param log <code>Log</code> implementation to use
*/
public final void setAbstractBeanWriterLog(Log log) {
this.log = log;
}
// SAX-style methods
//-------------------------------------------------------------------------
/**
* Writes the start tag for an element.
*
* @param uri the element's namespace uri
* @param localName the element's local name
* @param qName the element's qualified name
* @param attr the element's attributes
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @since 0.5
*/
protected void startElement(
WriteContext context,
String uri,
String localName,
String qName,
Attributes attr)
throws
IOException,
SAXException {
// for backwards compatbility call older methods
startElement(uri, localName, qName, attr);
}
/**
* Writes the end tag for an element
*
* @param uri the element's namespace uri
* @param localName the element's local name
* @param qName the element's qualified name
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @since 0.5
*/
protected void endElement(
WriteContext context,
String uri,
String localName,
String qName)
throws
IOException,
SAXException {
// for backwards compatibility call older interface
endElement(uri, localName, qName);
}
/**
* Writes body text
*
* @param text the body text to be written
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @since 0.5
*/
protected void bodyText(WriteContext context, String text)
throws IOException, SAXException {
// for backwards compatibility call older interface
bodyText(text);
}
// Older SAX-style methods
//-------------------------------------------------------------------------
/**
* Writes the start tag for an element.
*
* @param uri the element's namespace uri
* @param localName the element's local name
* @param qName the element's qualified name
* @param attr the element's attributes
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 use {@link #startElement(WriteContext, String, String, String, Attributes)}
*/
protected void startElement(
String uri,
String localName,
String qName,
Attributes attr)
throws
IOException,
SAXException {}
/**
* Writes the end tag for an element
*
* @param uri the element's namespace uri
* @param localName the element's local name
* @param qName the element's qualified name
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 use {@link #endElement(WriteContext, String, String, String)}
*/
protected void endElement(
String uri,
String localName,
String qName)
throws
IOException,
SAXException {}
/**
* Writes body text
*
* @param text the body text to be written
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 use {@link #bodyText(WriteContext, String)}
*/
protected void bodyText(String text) throws IOException, SAXException {}
// Implementation methods
//-------------------------------------------------------------------------
/**
* Writes the given element
*
* @param namespaceUri the namespace uri
* @param localName the local name
* @param qualifiedName qualified name to use for the element
* @param elementDescriptor the <code>ElementDescriptor</code> describing the element
* @param context the <code>Context</code> to use to evaluate the bean expressions
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
*/
private void writeElement(
String namespaceUri,
String localName,
String qualifiedName,
ElementDescriptor elementDescriptor,
Context context )
throws
IOException,
SAXException,
IntrospectionException {
if( log.isTraceEnabled() ) {
log.trace( "Writing: " + qualifiedName + " element: " + elementDescriptor );
}
if ( !ignoreElement( elementDescriptor, context )) {
if ( log.isTraceEnabled() ) {
log.trace( "Element " + elementDescriptor + " is empty." );
}
if (elementDescriptor.isWrapCollectionsInElement()) {
writeContext.setCurrentDescriptor(elementDescriptor);
startElement(
writeContext,
namespaceUri,
localName,
qualifiedName,
new ElementAttributes( elementDescriptor, context ));
}
writeElementContent( elementDescriptor, context ) ;
if ( elementDescriptor.isWrapCollectionsInElement() ) {
writeContext.setCurrentDescriptor(elementDescriptor);
endElement( writeContext, namespaceUri, localName, qualifiedName );
}
}
}
/**
* Writes the given element adding an ID attribute
*
* @param namespaceUri the namespace uri
* @param localName the local name
* @param qualifiedName the qualified name
* @param elementDescriptor the ElementDescriptor describing this element
* @param context the context being evaliated against
* @param idAttribute the qualified name of the <code>ID</code> attribute
* @param idValue the value for the <code>ID</code> attribute
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
*/
private void writeElement(
String namespaceUri,
String localName,
String qualifiedName,
ElementDescriptor elementDescriptor,
Context context,
String idAttribute,
String idValue )
throws
IOException,
SAXException,
IntrospectionException {
if ( !ignoreElement( elementDescriptor, context ) ) {
writeContext.setCurrentDescriptor(elementDescriptor);
startElement(
writeContext,
namespaceUri,
localName,
qualifiedName,
new ElementAttributes(
elementDescriptor,
context,
idAttribute,
idValue ));
writeElementContent( elementDescriptor, context ) ;
writeContext.setCurrentDescriptor(elementDescriptor);
endElement( writeContext, namespaceUri, localName, qualifiedName );
} else if ( log.isTraceEnabled() ) {
log.trace( "Element " + qualifiedName + " is empty." );
}
}
/**
* Write attributes, child elements and element end
*
* @param uri the element namespace uri
* @param localName the local name of the element
* @param qualifiedName the qualified name of the element
* @param elementDescriptor the descriptor for this element
* @param context evaluate against this context
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
*/
private void writeRestOfElement(
String uri,
String localName,
String qualifiedName,
ElementDescriptor elementDescriptor,
Context context )
throws
IOException,
SAXException,
IntrospectionException {
if ( elementDescriptor.isWrapCollectionsInElement() ) {
writeAttributes( elementDescriptor, context );
}
writeElementContent( elementDescriptor, context );
if ( elementDescriptor.isWrapCollectionsInElement() ) {
endElement( writeContext, uri, localName, qualifiedName );
}
}
/**
* Writes an element with a <code>IDREF</code> attribute
*
* @param uri the namespace uri
* @param localName the local name
* @param qualifiedName of the element with <code>IDREF</code> attribute
* @param idrefAttributeName the qualified name of the <code>IDREF</code> attribute
* @param idrefAttributeValue the value for the <code>IDREF</code> attribute
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
*/
private void writeIDREFElement(
ElementDescriptor elementDescriptor,
String uri,
String localName,
String qualifiedName,
String idrefAttributeName,
String idrefAttributeValue )
throws
IOException,
SAXException,
IntrospectionException {
// write IDREF element
AttributesImpl attributes = new AttributesImpl();
// XXX for the moment, assign IDREF to default namespace
attributes.addAttribute(
"",
idrefAttributeName,
idrefAttributeName,
"IDREF",
idrefAttributeValue);
writeContext.setCurrentDescriptor(elementDescriptor);
startElement( writeContext, uri, localName, qualifiedName, attributes);
endElement( writeContext, uri, localName, qualifiedName );
}
/**
* Writes the element content.
*
* @param elementDescriptor the <code>ElementDescriptor</code> to write as xml
* @param context the <code>Context</code> to use to evaluate the bean expressions
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
*/
private void writeElementContent(
ElementDescriptor elementDescriptor,
Context context )
throws
IOException,
SAXException,
IntrospectionException {
writeContext.setCurrentDescriptor( elementDescriptor );
Descriptor[] childDescriptors = elementDescriptor.getContentDescriptors();
if ( childDescriptors != null && childDescriptors.length > 0 ) {
// process child elements
for ( int i = 0, size = childDescriptors.length; i < size; i++ ) {
if (childDescriptors[i] instanceof ElementDescriptor) {
// Element content
ElementDescriptor childDescriptor = (ElementDescriptor) childDescriptors[i];
Context childContext = context;
Expression childExpression = childDescriptor.getContextExpression();
if ( childExpression != null ) {
Object childBean = childExpression.evaluate( context );
if ( childBean != null ) {
String qualifiedName = childDescriptor.getQualifiedName();
String namespaceUri = childDescriptor.getURI();
String localName = childDescriptor.getLocalName();
// XXXX: should we handle nulls better
if ( childBean instanceof Iterator ) {
for ( Iterator iter = (Iterator) childBean; iter.hasNext(); ) {
Object object = iter.next();
if (object == null) {
continue;
}
writeBean(
namespaceUri,
localName,
qualifiedName,
object,
context );
}
} else {
writeBean(
namespaceUri,
localName,
qualifiedName,
childBean,
context );
}
}
} else {
writeElement(
childDescriptor.getURI(),
childDescriptor.getLocalName(),
childDescriptor.getQualifiedName(),
childDescriptor,
childContext );
}
} else {
// Mixed text content
// evaluate the body text
Expression expression = childDescriptors[i].getTextExpression();
if ( expression != null ) {
Object value = expression.evaluate( context );
String text = convertToString(
value,
childDescriptors[i],
context );
if ( text != null && text.length() > 0 ) {;
bodyText( writeContext, text );
}
}
}
}
} else {
// evaluate the body text
Expression expression = elementDescriptor.getTextExpression();
if ( expression != null ) {
Object value = expression.evaluate( context );
String text = convertToString( value, elementDescriptor, context );
if ( text != null && text.length() > 0 ) {
bodyText( writeContext, text );
}
}
}
}
/**
* Pushes the bean onto the ancestry stack.
* If IDs are not being written, then check for cyclic references.
*
* @param bean push this bean onto the ancester stack
*/
protected void pushBean( Object bean ) {
// check that we don't have a cyclic reference when we're not writing IDs
if ( !getBindingConfiguration().getMapIDs() ) {
Iterator it = beanStack.iterator();
while ( it.hasNext() ) {
Object next = it.next();
// use absolute equality rather than equals
// we're only really bothered if objects are actually the same
if ( bean == next ) {
if ( log.isDebugEnabled() ) {
log.debug("Element stack: ");
Iterator debugStack = beanStack.iterator();
while ( debugStack.hasNext() ) {
log.debug(debugStack.next());
}
}
log.error("Cyclic reference at bean: " + bean);
throw new CyclicReferenceException();
}
}
}
if (log.isTraceEnabled()) {
log.trace( "Pushing onto object stack: " + bean );
}
beanStack.push( bean );
}
/**
* Pops the top bean off from the ancestry stack
*
* @return the last object pushed onto the ancester stack
*/
protected Object popBean() {
Object bean = beanStack.pop();
if (log.isTraceEnabled()) {
log.trace( "Popped from object stack: " + bean );
}
return bean;
}
/**
* Should this element (and children) be written out?
*
* @param descriptor the <code>ElementDescriptor</code> to evaluate
* @param context the <code>Context</code> against which the element will be evaluated
* @return true if this element should be written out
*/
private boolean ignoreElement( ElementDescriptor descriptor, Context context ) {
if ( ! getWriteEmptyElements() ) {
return isEmptyElement( descriptor, context );
}
return false;
}
/**
* <p>Will evaluating this element against this context result in an empty element?</p>
*
* <p>An empty element is one that has no attributes, no child elements
* and no body text.
* For example, <code><element/></code> is an empty element but
* <code><element attr='value'/></code> is not.</p>
*
* @param descriptor the <code>ElementDescriptor</code> to evaluate
* @param context the <code>Context</code> against which the element will be evaluated
* @return true if this element is empty on evaluation
*/
private boolean isEmptyElement( ElementDescriptor descriptor, Context context ) {
if ( log.isTraceEnabled() ) {
log.trace( "Is " + descriptor + " empty?" );
}
// an element which has attributes is not empty
if ( descriptor.hasAttributes() ) {
log.trace( "Element has attributes." );
return false;
}
// an element is not empty if it has a non-empty body
Expression expression = descriptor.getTextExpression();
if ( expression != null ) {
Object value = expression.evaluate( context );
String text = convertToString( value, descriptor, context );
if ( text != null && text.length() > 0 ) {
log.trace( "Element has body text which isn't empty." );
return false;
}
}
// always write out loops - even when they have no elements
if ( XMLIntrospectorHelper.isLoopType( descriptor.getPropertyType() ) ) {
log.trace("Loop type so not empty.");
return false;
}
// now test child elements
// an element is empty if it has no non-empty child elements
if ( descriptor.hasChildren() ) {
for ( int i=0, size=descriptor.getElementDescriptors().length; i<size; i++ ) {
if ( ! isEmptyElement( descriptor.getElementDescriptors()[i], context ) ) {
log.trace( "Element has child which isn't empty." );
return false;
}
}
}
log.trace( "Element is empty." );
return true;
}
/**
* Attributes backed by attribute descriptors
*/
private class ElementAttributes implements Attributes {
/** Attribute descriptors backing the <code>Attributes</code> */
private AttributeDescriptor[] attributes;
/** Context to be evaluated when finding values */
private Context context;
/** ID attribute value */
private String idValue;
/** ID attribute name */
private String idAttributeName;
/**
* Construct attributes for element and context.
*
* @param descriptor the <code>ElementDescriptor</code> describing the element
* @param context evaluate against this context
*/
ElementAttributes( ElementDescriptor descriptor, Context context ) {
attributes = descriptor.getAttributeDescriptors();
this.context = context;
}
/**
* Construct attributes for element and context.
*
* @param descriptor the <code>ElementDescriptor</code> describing the element
* @param context evaluate against this context
* @param idAttributeName the name of the id attribute
* @param idValue the ID attribute value
*/
ElementAttributes(
ElementDescriptor descriptor,
Context context,
String idAttributeName,
String idValue) {
attributes = descriptor.getAttributeDescriptors();
this.context = context;
this.idValue = idValue;
this.idAttributeName = idAttributeName;
}
/**
* Gets the index of an attribute by qualified name.
*
* @param qName the qualified name of the attribute
* @return the index of the attribute - or -1 if there is no matching attribute
*/
public int getIndex( String qName ) {
for ( int i=0; i<attributes.length; i++ ) {
if (attributes[i].getQualifiedName() != null
&& attributes[i].getQualifiedName().equals( qName )) {
return i;
}
}
return -1;
}
/**
* Gets the index of an attribute by namespace name.
*
* @param uri the namespace uri of the attribute
* @param localName the local name of the attribute
* @return the index of the attribute - or -1 if there is no matching attribute
*/
public int getIndex( String uri, String localName ) {
for ( int i=0; i<attributes.length; i++ ) {
if (
attributes[i].getURI() != null
&& attributes[i].getURI().equals(uri)
&& attributes[i].getLocalName() != null
&& attributes[i].getURI().equals(localName)) {
return i;
}
}
return -1;
}
/**
* Gets the number of attributes in the list.
*
* @return the number of attributes in this list
*/
public int getLength() {
return attributes.length;
}
/**
* Gets the local name by index.
*
* @param index the attribute index (zero based)
* @return the attribute local name - or null if the index is out of range
*/
public String getLocalName( int index ) {
if ( indexInRange( index ) ) {
return attributes[index].getLocalName();
}
return null;
}
/**
* Gets the qualified name by index.
*
* @param index the attribute index (zero based)
* @return the qualified name of the element - or null if the index is our of range
*/
public String getQName( int index ) {
if ( indexInRange( index ) ) {
return attributes[index].getQualifiedName();
}
return null;
}
/**
* Gets the attribute SAX type by namespace name.
*
* @param index the attribute index (zero based)
* @return the attribute type (as a string) or null if the index is out of range
*/
public String getType( int index ) {
if ( indexInRange( index ) ) {
return "CDATA";
}
return null;
}
/**
* Gets the attribute SAX type by qualified name.
*
* @param qName the qualified name of the attribute
* @return the attribute type (as a string) or null if the attribute is not in the list
*/
public String getType( String qName ) {
return getType( getIndex( qName ) );
}
/**
* Gets the attribute SAX type by namespace name.
*
* @param uri the namespace uri of the attribute
* @param localName the local name of the attribute
* @return the attribute type (as a string) or null if the attribute is not in the list
*/
public String getType( String uri, String localName ) {
return getType( getIndex( uri, localName ));
}
/**
* Gets the namespace URI for attribute at the given index.
*
* @param index the attribute index (zero-based)
* @return the namespace URI (empty string if none is available)
* or null if the index is out of range
*/
public String getURI( int index ) {
if ( indexInRange( index ) ) {
return attributes[index].getURI();
}
return null;
}
/**
* Gets the value for the attribute at given index.
*
* @param index the attribute index (zero based)
* @return the attribute value or null if the index is out of range
* @todo add value caching
*/
public String getValue( int index ) {
if ( indexInRange( index )) {
if (
idAttributeName != null
&& idAttributeName.equals(attributes[index].getLocalName())) {
return idValue;
} else {
Expression expression = attributes[index].getTextExpression();
if ( expression != null ) {
Object value = expression.evaluate( context );
return convertToString( value, attributes[index], context );
}
}
return "";
}
return null;
}
/**
* Gets the value for the attribute by qualified name.
*
* @param qName the qualified name
* @return the attribute value or null if there are no attributes
* with the given qualified name
* @todo add value caching
*/
public String getValue( String qName ) {
return getValue( getIndex( qName ) );
}
/**
* Gets the value for the attribute by namespace name.
*
* @param uri the namespace URI of the attribute
* @param localName the local name of the attribute
* @return the attribute value or null if there are not attributes
* with the given namespace and local name
* @todo add value caching
*/
public String getValue( String uri, String localName ) {
return getValue( getIndex( uri, localName ) );
}
/**
* Is the given index within the range of the attribute list
*
* @param index the index whose range will be checked
* @return true if the index with within the range of the attribute list
*/
private boolean indexInRange( int index ) {
return ( index >= 0 && index < attributes.length );
}
}
// OLD API (DEPRECATED)
// --------------------------------------------------------------------------------------
/**
* Get the indentation for the current element.
* Used for pretty priting.
*
* @return the amount that the current element is indented
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected int getIndentLevel() {
return 0;
}
// Expression methods
//-------------------------------------------------------------------------
/**
* Express an element tag start using given qualified name.
*
* @param qualifiedName the qualified name of the element to be expressed
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void expressElementStart(String qualifiedName)
throws IOException, SAXException {
// do nothing
}
/**
* Express an element tag start using given qualified name.
*
* @param uri the namespace uri
* @param localName the local name for this element
* @param qualifiedName the qualified name of the element to be expressed
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void expressElementStart(String uri, String localName, String qualifiedName)
throws IOException, SAXException {
expressElementStart( qualifiedName );
}
/**
* Express a closing tag.
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void expressTagClose() throws IOException, SAXException {}
/**
* Express an element end tag (with given name)
*
* @param qualifiedName the qualified name for the element to be closed
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void expressElementEnd(String qualifiedName)
throws IOException, SAXException {
// do nothing
}
/**
* Express an element end tag (with given name)
*
* @param uri the namespace uri of the element close tag
* @param localName the local name of the element close tag
* @param qualifiedName the qualified name for the element to be closed
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void expressElementEnd(
String uri,
String localName,
String qualifiedName)
throws
IOException,
SAXException {
expressElementEnd(qualifiedName);
}
/**
* Express an empty element end.
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void expressElementEnd() throws IOException, SAXException {}
/**
* Express body text
*
* @param text the string to write out as the body of the current element
*
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void expressBodyText(String text) throws IOException, SAXException {}
/**
* Express an attribute
*
* @param qualifiedName the qualified name of the attribute
* @param value the attribute value
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void expressAttribute(
String qualifiedName,
String value)
throws
IOException,
SAXException {
// Do nothing
}
/**
* Express an attribute
*
* @param namespaceUri the namespace uri
* @param localName the local name
* @param qualifiedName the qualified name of the attribute
* @param value the attribute value
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void expressAttribute(
String namespaceUri,
String localName,
String qualifiedName,
String value)
throws
IOException,
SAXException {
expressAttribute(qualifiedName, value);
}
/**
* Writes the given element
*
* @param qualifiedName qualified name to use for the element
* @param elementDescriptor the <code>ElementDescriptor</code> describing the element
* @param context the <code>Context</code> to use to evaluate the bean expressions
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void write(
String qualifiedName,
ElementDescriptor elementDescriptor,
Context context )
throws
IOException,
SAXException,
IntrospectionException {
writeElement( "", qualifiedName, qualifiedName, elementDescriptor, context );
}
/**
* Writes the given element adding an ID attribute
*
* @param qualifiedName qualified name to use for the element
* @param elementDescriptor the <code>ElementDescriptor</code> describing the element
* @param context the <code>Context</code> to use to evaluate the bean expressions
* @param idAttribute the qualified name of the <code>ID</code> attribute
* @param idValue the value for the <code>ID</code> attribute
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void write(
String qualifiedName,
ElementDescriptor elementDescriptor,
Context context,
String idAttribute,
String idValue )
throws
IOException,
SAXException,
IntrospectionException {
writeElement(
"",
qualifiedName,
qualifiedName,
elementDescriptor,
context,
idAttribute,
idValue );
}
/**
* Write attributes, child elements and element end
*
* @param qualifiedName qualified name to use for the element
* @param elementDescriptor the <code>ElementDescriptor</code> describing the element
* @param context the <code>Context</code> to use to evaluate the bean expressions
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void writeRestOfElement(
String qualifiedName,
ElementDescriptor elementDescriptor,
Context context )
throws
IOException,
SAXException,
IntrospectionException {
writeRestOfElement( "", qualifiedName, qualifiedName, elementDescriptor, context );
}
/**
* Writes an element with a <code>IDREF</code> attribute
*
* @param qualifiedName of the element with <code>IDREF</code> attribute
* @param idrefAttributeName the qualified name of the <code>IDREF</code> attribute
* @param idrefAttributeValue the value for the <code>IDREF</code> attribute
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void writeIDREFElement(
String qualifiedName,
String idrefAttributeName,
String idrefAttributeValue )
throws
IOException,
SAXException,
IntrospectionException {
// deprecated
AttributesImpl attributes = new AttributesImpl();
attributes.addAttribute(
"",
idrefAttributeName,
idrefAttributeName,
"IDREF",
idrefAttributeValue);
startElement( "", qualifiedName, qualifiedName, attributes);
endElement( "", qualifiedName, qualifiedName );
}
/**
* Writes the element content.
*
* @param elementDescriptor the <code>ElementDescriptor</code> to write as xml
* @param context the <code>Context</code> to use to evaluate the bean expressions
* @return true if some content was written
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @throws IntrospectionException if a java beans introspection problem occurs
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected boolean writeContent(
ElementDescriptor elementDescriptor,
Context context )
throws
IOException,
SAXException,
IntrospectionException {
return false;
}
/**
* Writes the attribute declarations
*
* @param elementDescriptor the <code>ElementDescriptor</code> to be written out as xml
* @param context the <code>Context</code> to use to evaluation bean expressions
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void writeAttributes(
ElementDescriptor elementDescriptor,
Context context )
throws
IOException, SAXException {
if (!elementDescriptor.isWrapCollectionsInElement()) {
return;
}
AttributeDescriptor[] attributeDescriptors = elementDescriptor.getAttributeDescriptors();
if ( attributeDescriptors != null ) {
for ( int i = 0, size = attributeDescriptors.length; i < size; i++ ) {
AttributeDescriptor attributeDescriptor = attributeDescriptors[i];
writeAttribute( attributeDescriptor, context );
}
}
}
/**
* Writes an attribute declaration
*
* @param attributeDescriptor the <code>AttributeDescriptor</code> to be written as xml
* @param context the <code>Context</code> to use to evaluation bean expressions
* @throws IOException if an IO problem occurs during writing
* @throws SAXException if an SAX problem occurs during writing
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void writeAttribute(
AttributeDescriptor attributeDescriptor,
Context context )
throws
IOException, SAXException {
Expression expression = attributeDescriptor.getTextExpression();
if ( expression != null ) {
Object value = expression.evaluate( context );
if ( value != null ) {
String text = value.toString();
if ( text != null && text.length() > 0 ) {
expressAttribute(
attributeDescriptor.getURI(),
attributeDescriptor.getLocalName(),
attributeDescriptor.getQualifiedName(),
text);
}
}
}
}
/**
* Writes a empty line.
* This implementation does nothing but can be overridden by subclasses.
*
* @throws IOException if the line cannot be written
* @deprecated 0.5 replaced by new SAX inspired API
*/
protected void writePrintln() throws IOException {}
/**
* Writes an indentation.
* This implementation does nothing but can be overridden by subclasses.
*
* @throws IOException if the indent cannot be written
* @deprecated 0.5 replaced by new BeanWriter API
*/
protected void writeIndent() throws IOException {}
/**
* Converts an object to a string.
*
* @param value the Object to represent as a String, possibly null
* @param descriptor writing out this descriptor not null
* @param context not null
* @return String representation, not null
*/
private String convertToString( Object value , Descriptor descriptor, Context context ) {
return getBindingConfiguration()
.getObjectStringConverter()
.objectToString( value, descriptor.getPropertyType(), null, context );
}
/**
* Factory method for new contexts.
* Ensure that they are correctly configured.
* @param bean make a new Context for this bean
* @return not null
*/
private Context makeContext(Object bean) {
return new Context( bean, log, bindingConfiguration );
}
/**
* Basic mutable implementation of <code>WriteContext</code>.
*/
private static class WriteContextImpl extends WriteContext {
private ElementDescriptor currentDescriptor;
/**
* @see org.apache.commons.betwixt.io.WriteContext#getCurrentDescriptor()
*/
public ElementDescriptor getCurrentDescriptor() {
return currentDescriptor;
}
/**
* Sets the descriptor for the current element.
* @param currentDescriptor
*/
public void setCurrentDescriptor(ElementDescriptor currentDescriptor) {
this.currentDescriptor = currentDescriptor;
}
}
}