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XMLTooling-J is a low-level library that may be used to construct libraries that allow developers to work with
XML in a Java beans manner.
/*
* Licensed to the University Corporation for Advanced Internet Development,
* Inc. (UCAID) under one or more contributor license agreements. See the
* NOTICE file distributed with this work for additional information regarding
* copyright ownership. The UCAID 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.
*/
package org.opensaml.xml.parse;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.lang.ref.SoftReference;
import java.util.Collections;
import java.util.Map;
import java.util.Stack;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.validation.Schema;
import org.opensaml.xml.Configuration;
import org.opensaml.xml.util.LazyMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.DOMImplementation;
import org.w3c.dom.Document;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;
/**
* A pool of JAXP 1.3 {@link DocumentBuilder}s.
*
* This implementation of {@link ParserPool} does not allow its properties to be modified once
* it has been initialized. For an implementation that does support versioned properties over
* time, see {@link BasicParserPool}.
*
* This is a pool implementation of the caching factory variety, and as such imposes no upper bound
* on the number of DocumentBuilders allowed to be concurrently checked out and in use. It does however
* impose a limit on the size of the internal cache of idle builder instances via the value configured
* via {@link #setMaxPoolSize(int)}.
*
* Builders retrieved from this pool may (but are not required to) be returned to the pool with the method
* {@link #returnBuilder(DocumentBuilder)}.
*
* References to builders are kept by way of {@link SoftReference} so that the garbage collector
* may reap the builders if the system is running out of memory.
*/
public class StaticBasicParserPool implements ParserPool {
/** Class logger. */
private final Logger log = LoggerFactory.getLogger(StaticBasicParserPool.class);
/** Flag to track whether pool is in the initialized state. */
private boolean initialized;
/** Factory used to create new builders. */
private DocumentBuilderFactory builderFactory;
/** Cache of document builders. */
private Stack> builderPool;
/** Max number of builders allowed in the pool. Default value: 5 */
private int maxPoolSize;
/** Builder attributes. */
private Map builderAttributes;
/** Whether the builders are coalescing. Default value: true */
private boolean coalescing;
/** Whether the builders expand entity references. Default value: true */
private boolean expandEntityReferences;
/** Builder features. */
private Map builderFeatures;
/** Whether the builders ignore comments. Default value: true */
private boolean ignoreComments;
/** Whether the builders ignore element content whitespace. Default value: true */
private boolean ignoreElementContentWhitespace;
/** Whether the builders are namespace aware. Default value: true */
private boolean namespaceAware;
/** Schema used to validate parsed content. */
private Schema schema;
/** Whether the builder should validate. Default value: false */
private boolean dtdValidating;
/** Whether the builders are XInclude aware. Default value: false */
private boolean xincludeAware;
/** Entity resolver used by builders. */
private EntityResolver entityResolver;
/** Error handler used by builders. */
private ErrorHandler errorHandler;
/** Constructor. */
public StaticBasicParserPool() {
initialized = false;
maxPoolSize = 5;
builderPool = new Stack>();
builderAttributes = new LazyMap();
coalescing = true;
expandEntityReferences = true;
builderFeatures = new LazyMap();
ignoreComments = true;
ignoreElementContentWhitespace = true;
namespaceAware = true;
schema = null;
dtdValidating = false;
xincludeAware = false;
errorHandler = new LoggingErrorHandler(log);
}
/**
* Initialize the pool.
*
* @throws XMLParserException thrown if pool can not be initialized,
* or if it is already initialized
*
**/
public synchronized void initialize() throws XMLParserException {
if (initialized) {
throw new XMLParserException("Parser pool was already initialized");
}
initializeFactory();
initialized = true;
}
/**
* Return initialized state.
*
* @return true if pool is initialized, false otherwise
*/
public synchronized boolean isInitialized() {
return initialized;
}
/** {@inheritDoc} */
public DocumentBuilder getBuilder() throws XMLParserException {
DocumentBuilder builder = null;
if (!initialized) {
throw new XMLParserException("Parser pool has not been initialized");
}
synchronized(builderPool) {
if (!builderPool.isEmpty()) {
builder = builderPool.pop().get();
}
}
// Will be null if either the stack was empty, or the SoftReference
// has been garbage-collected
if (builder == null) {
builder = createBuilder();
}
if (builder != null) {
return new DocumentBuilderProxy(builder, this);
}
return null;
}
/** {@inheritDoc} */
public void returnBuilder(DocumentBuilder builder) {
if (!(builder instanceof DocumentBuilderProxy)) {
return;
}
DocumentBuilderProxy proxiedBuilder = (DocumentBuilderProxy) builder;
if (proxiedBuilder.getOwningPool() != this) {
return;
}
synchronized (proxiedBuilder) {
if (proxiedBuilder.isReturned()) {
return;
}
// Not strictly true in that it may not actually be pushed back
// into the cache, depending on builderPool.size() below. But
// that's ok. returnBuilder() shouldn't normally be called twice
// on the same builder instance anyway, and it also doesn't matter
// whether a builder is ever logically returned to the pool.
proxiedBuilder.setReturned(true);
}
DocumentBuilder unwrappedBuilder = proxiedBuilder.getProxiedBuilder();
unwrappedBuilder.reset();
SoftReference builderReference = new SoftReference(unwrappedBuilder);
synchronized(builderPool) {
if (builderPool.size() < maxPoolSize) {
builderPool.push(builderReference);
}
}
}
/** {@inheritDoc} */
public Document newDocument() throws XMLParserException {
DocumentBuilder builder = getBuilder();
Document document = builder.newDocument();
returnBuilder(builder);
return document;
}
/** {@inheritDoc} */
public Document parse(InputStream input) throws XMLParserException {
DocumentBuilder builder = getBuilder();
try {
Document document = builder.parse(input);
return document;
} catch (SAXException e) {
throw new XMLParserException("Invalid XML", e);
} catch (IOException e) {
throw new XMLParserException("Unable to read XML from input stream", e);
} finally {
returnBuilder(builder);
}
}
/** {@inheritDoc} */
public Document parse(Reader input) throws XMLParserException {
DocumentBuilder builder = getBuilder();
try {
Document document = builder.parse(new InputSource(input));
return document;
} catch (SAXException e) {
throw new XMLParserException("Invalid XML", e);
} catch (IOException e) {
throw new XMLParserException("Unable to read XML from input stream", e);
} finally {
returnBuilder(builder);
}
}
/**
* Gets the max number of builders the pool will hold.
*
* @return max number of builders the pool will hold
*/
public int getMaxPoolSize() {
return maxPoolSize;
}
/**
* Sets the max number of builders the pool will hold.
*
* @param newSize max number of builders the pool will hold
*/
public void setMaxPoolSize(int newSize) {
checkValidModifyState();
maxPoolSize = newSize;
}
/**
* Gets the builder attributes used when creating builders. This collection is unmodifiable.
*
* @return builder attributes used when creating builders
*/
public Map getBuilderAttributes() {
return Collections.unmodifiableMap(builderAttributes);
}
/**
* Sets the builder attributes used when creating builders.
*
* @param newAttributes builder attributes used when creating builders
*/
public void setBuilderAttributes(Map newAttributes) {
checkValidModifyState();
builderAttributes = newAttributes;
}
/**
* Gets whether the builders are coalescing.
*
* @return whether the builders are coalescing
*/
public boolean isCoalescing() {
return coalescing;
}
/**
* Sets whether the builders are coalescing.
*
* @param isCoalescing whether the builders are coalescing
*/
public void setCoalescing(boolean isCoalescing) {
checkValidModifyState();
coalescing = isCoalescing;
}
/**
* Gets whether builders expand entity references.
*
* @return whether builders expand entity references
*/
public boolean isExpandEntityReferences() {
return expandEntityReferences;
}
/**
* Sets whether builders expand entity references.
*
* @param expand whether builders expand entity references
*/
public void setExpandEntityReferences(boolean expand) {
checkValidModifyState();
expandEntityReferences = expand;
}
/**
* Gets the builders' features. This collection is unmodifiable.
*
* @return the builders' features
*/
public Map getBuilderFeatures() {
return Collections.unmodifiableMap(builderFeatures);
}
/**
* Sets the the builders' features.
*
* @param newFeatures the builders' features
*/
public void setBuilderFeatures(Map newFeatures) {
checkValidModifyState();
builderFeatures = newFeatures;
}
/**
* Gets whether the builders ignore comments.
*
* @return whether the builders ignore comments
*/
public boolean getIgnoreComments() {
return ignoreComments;
}
/**
* Sets whether the builders ignore comments.
*
* @param ignore The ignoreComments to set.
*/
public void setIgnoreComments(boolean ignore) {
checkValidModifyState();
ignoreComments = ignore;
}
/**
* Get whether the builders ignore element content whitespace.
*
* @return whether the builders ignore element content whitespace
*/
public boolean isIgnoreElementContentWhitespace() {
return ignoreElementContentWhitespace;
}
/**
* Sets whether the builders ignore element content whitespace.
*
* @param ignore whether the builders ignore element content whitespace
*/
public void setIgnoreElementContentWhitespace(boolean ignore) {
checkValidModifyState();
ignoreElementContentWhitespace = ignore;
}
/**
* Gets whether the builders are namespace aware.
*
* @return whether the builders are namespace aware
*/
public boolean isNamespaceAware() {
return namespaceAware;
}
/**
* Sets whether the builders are namespace aware.
*
* @param isNamespaceAware whether the builders are namespace aware
*/
public void setNamespaceAware(boolean isNamespaceAware) {
checkValidModifyState();
namespaceAware = isNamespaceAware;
}
/** {@inheritDoc} */
public Schema getSchema() {
return schema;
}
/** {@inheritDoc} */
public synchronized void setSchema(Schema newSchema) {
// Note this method is synchronized because it is more than just an atomic assignment.
// Don't want inconsistent data in the factory via initializeFactory(), also synchronized.
checkValidModifyState();
schema = newSchema;
if (schema != null) {
setNamespaceAware(true);
builderAttributes.remove("http://java.sun.com/xml/jaxp/properties/schemaSource");
builderAttributes.remove("http://java.sun.com/xml/jaxp/properties/schemaLanguage");
}
}
/**
* Gets whether the builders are validating.
*
* @return whether the builders are validating
*/
public boolean isDTDValidating() {
return dtdValidating;
}
/**
* Sets whether the builders are validating.
*
* @param isValidating whether the builders are validating
*/
public void setDTDValidating(boolean isValidating) {
checkValidModifyState();
dtdValidating = isValidating;
}
/**
* Gets whether the builders are XInclude aware.
*
* @return whether the builders are XInclude aware
*/
public boolean isXincludeAware() {
return xincludeAware;
}
/**
* Sets whether the builders are XInclude aware.
*
* @param isXIncludeAware whether the builders are XInclude aware
*/
public void setXincludeAware(boolean isXIncludeAware) {
checkValidModifyState();
xincludeAware = isXIncludeAware;
}
/**
* Gets the size of the current pool storage.
*
* @return current pool storage size
*/
protected int getPoolSize() {
return builderPool.size();
}
/**
* Check that pool is in a valid state to be modified.
*/
protected void checkValidModifyState() {
if (initialized) {
throw new IllegalStateException("Pool is already initialized, property changes not allowed");
}
}
/**
* Initializes the pool with a new set of configuration options.
*
* @throws XMLParserException thrown if there is a problem initialzing the pool
*/
protected synchronized void initializeFactory() throws XMLParserException {
DocumentBuilderFactory newFactory = DocumentBuilderFactory.newInstance();
setAttributes(newFactory, builderAttributes);
setFeatures(newFactory, builderFeatures);
newFactory.setCoalescing(coalescing);
newFactory.setExpandEntityReferences(expandEntityReferences);
newFactory.setIgnoringComments(ignoreComments);
newFactory.setIgnoringElementContentWhitespace(ignoreElementContentWhitespace);
newFactory.setNamespaceAware(namespaceAware);
newFactory.setSchema(schema);
newFactory.setValidating(dtdValidating);
newFactory.setXIncludeAware(xincludeAware);
builderFactory = newFactory;
}
/**
* Sets document builder attributes. If an attribute is not supported it is ignored.
*
* @param factory document builder factory upon which the attribute will be set
* @param attributes the set of attributes to be set
*/
protected void setAttributes(DocumentBuilderFactory factory, Map attributes) {
if (attributes == null || attributes.isEmpty()) {
return;
}
for (Map.Entry attribute : attributes.entrySet()) {
try {
log.debug("Setting DocumentBuilderFactory attribute '{}'", attribute.getKey());
factory.setAttribute(attribute.getKey(), attribute.getValue());
} catch (IllegalArgumentException e) {
log.warn("DocumentBuilderFactory attribute '{}' is not supported", attribute.getKey());
}
}
}
/**
* Sets document builder features. If an features is not supported it is ignored.
*
* @param factory document builder factory upon which the attribute will be set
* @param features the set of features to be set
*/
protected void setFeatures(DocumentBuilderFactory factory, Map features) {
if (features == null || features.isEmpty()) {
return;
}
for (Map.Entry feature : features.entrySet()) {
try {
log.debug("Setting DocumentBuilderFactory attribute '{}'", feature.getKey());
factory.setFeature(feature.getKey(), feature.getValue());
} catch (ParserConfigurationException e) {
log.warn("DocumentBuilderFactory feature '{}' is not supported", feature.getKey());
}
}
}
/**
* Creates a new document builder.
*
* @return newly created document builder
*
* @throws XMLParserException thrown if their is a configuration error with the builder factory
*/
protected DocumentBuilder createBuilder() throws XMLParserException {
try {
DocumentBuilder builder = builderFactory.newDocumentBuilder();
if (entityResolver != null) {
builder.setEntityResolver(entityResolver);
}
if (errorHandler != null) {
builder.setErrorHandler(errorHandler);
}
return builder;
} catch (ParserConfigurationException e) {
log.error("Unable to create new document builder", e);
throw new XMLParserException("Unable to create new document builder", e);
}
}
/**
* A proxy that prevents the manages document builders retrieved from the parser pool.
*/
protected class DocumentBuilderProxy extends DocumentBuilder {
/** Builder being proxied. */
private DocumentBuilder builder;
/** Pool that owns this parser. */
private ParserPool owningPool;
/** Track accounting state of whether this builder has been returned to the owning pool. */
private boolean returned;
/**
* Constructor.
*
* @param target document builder to proxy
* @param owner the owning pool
*/
public DocumentBuilderProxy(DocumentBuilder target, StaticBasicParserPool owner) {
owningPool = owner;
builder = target;
returned = false;
}
/** {@inheritDoc} */
public DOMImplementation getDOMImplementation() {
checkValidState();
return builder.getDOMImplementation();
}
/** {@inheritDoc} */
public Schema getSchema() {
checkValidState();
return builder.getSchema();
}
/** {@inheritDoc} */
public boolean isNamespaceAware() {
checkValidState();
return builder.isNamespaceAware();
}
/** {@inheritDoc} */
public boolean isValidating() {
checkValidState();
return builder.isValidating();
}
/** {@inheritDoc} */
public boolean isXIncludeAware() {
checkValidState();
return builder.isXIncludeAware();
}
/** {@inheritDoc} */
public Document newDocument() {
checkValidState();
return builder.newDocument();
}
/** {@inheritDoc} */
public Document parse(File f) throws SAXException, IOException {
checkValidState();
return builder.parse(f);
}
/** {@inheritDoc} */
public Document parse(InputSource is) throws SAXException, IOException {
checkValidState();
return builder.parse(is);
}
/** {@inheritDoc} */
public Document parse(InputStream is) throws SAXException, IOException {
checkValidState();
return builder.parse(is);
}
/** {@inheritDoc} */
public Document parse(InputStream is, String systemId) throws SAXException, IOException {
checkValidState();
return builder.parse(is, systemId);
}
/** {@inheritDoc} */
public Document parse(String uri) throws SAXException, IOException {
checkValidState();
return builder.parse(uri);
}
/** {@inheritDoc} */
public void reset() {
// ignore, entity resolver and error handler can't be changed
}
/** {@inheritDoc} */
public void setEntityResolver(EntityResolver er) {
checkValidState();
return;
}
/** {@inheritDoc} */
public void setErrorHandler(ErrorHandler eh) {
checkValidState();
return;
}
/**
* Gets the pool that owns this parser.
*
* @return pool that owns this parser
*/
protected ParserPool getOwningPool() {
return owningPool;
}
/**
* Gets the proxied document builder.
*
* @return proxied document builder
*/
protected DocumentBuilder getProxiedBuilder() {
return builder;
}
/**
* Check accounting state as to whether this parser has been returned to the
* owning pool.
*
* @return true if parser has been returned to the owning pool, otherwise false
*/
protected boolean isReturned() {
return returned;
}
/**
* Set accounting state as to whether this parser has been returned to the
* owning pool.
*
* @param isReturned set true to indicate that parser has been returned to the owning pool
*/
protected void setReturned(boolean isReturned) {
this.returned = isReturned;
}
/**
* Check whether the parser is in a valid and usable state, and if not, throw a runtime exception.
*
* @throws IllegalStateException thrown if the parser is in a state such that it can not be used
*/
protected void checkValidState() throws IllegalStateException {
if (isReturned()) {
throw new IllegalStateException("DocumentBuilderProxy has already been returned to its owning pool");
}
}
/** {@inheritDoc} */
protected void finalize() throws Throwable {
super.finalize();
owningPool.returnBuilder(this);
}
}
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