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Xerces2 is the next generation of high performance, fully compliant XML parsers in the Apache Xerces family.
This new version of Xerces introduces the Xerces Native Interface (XNI), a complete framework for building
parser components and configurations that is extremely modular and easy to program. The Apache Xerces2 parser is
the reference implementation of XNI but other parser components, configurations, and parsers can be written
using the Xerces Native Interface. For complete design and implementation documents, refer to the XNI Manual.
Xerces2 is a fully conforming XML Schema 1.0 processor. A partial experimental implementation of the XML Schema
1.1 Structures and Datatypes Working Drafts (December 2009) and an experimental implementation of the XML Schema
Definition Language (XSD): Component Designators (SCD) Candidate Recommendation (January 2010) are provided for
evaluation. For more information, refer to the XML Schema page. Xerces2 also provides a complete implementation
of the Document Object Model Level 3 Core and Load/Save W3C Recommendations and provides a complete
implementation of the XML Inclusions (XInclude) W3C Recommendation. It also provides support for OASIS XML
Catalogs v1.1. Xerces2 is able to parse documents written according to the XML 1.1 Recommendation, except that
it does not yet provide an option to enable normalization checking as described in section 2.13 of this
specification. It also handles namespaces according to the XML Namespaces 1.1 Recommendation, and will correctly
serialize XML 1.1 documents if the DOM level 3 load/save APIs are in use.
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/*
* 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.
*/
// $Id: SchemaFactoryFinder.java 727367 2008-12-17 13:05:26Z mrglavas $
package javax.xml.validation;
import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Properties;
import javax.xml.XMLConstants;
/**
* Implementation of {@link SchemaFactory#newInstance(String)}.
*
* @author Kohsuke Kawaguchi
* @version $Revision: 727367 $, $Date: 2008-12-17 08:05:26 -0500 (Wed, 17 Dec 2008) $
* @since 1.5
*/
final class SchemaFactoryFinder {
/** XML Schema language identifiers. */
private static final String W3C_XML_SCHEMA10_NS_URI = "http://www.w3.org/XML/XMLSchema/v1.0";
private static final String W3C_XML_SCHEMA11_NS_URI = "http://www.w3.org/XML/XMLSchema/v1.1";
/** debug support code. */
private static boolean debug = false;
/**
* Cache properties for performance.
*/
private static Properties cacheProps = new Properties();
/**
* First time requires initialization overhead.
*/
private static boolean firstTime = true;
/**
* Default columns per line.
*/
private static final int DEFAULT_LINE_LENGTH = 80;
static {
// Use try/catch block to support applets
try {
String val = SecuritySupport.getSystemProperty("jaxp.debug");
// Allow simply setting the prop to turn on debug
debug = val != null && (! "false".equals(val));
} catch (Exception _) {
debug = false;
}
}
/**
* Conditional debug printing.
*
* @param msg to print
*/
private static void debugPrintln(String msg) {
if (debug) {
System.err.println("JAXP: " + msg);
}
}
/**
* ClassLoader to use to find SchemaFactory.
*/
private final ClassLoader classLoader;
/**
* Constructor that specifies ClassLoader to use
* to find SchemaFactory.
*
* @param loader
* to be used to load resource, {@link SchemaFactory}, and
* {@link SchemaFactoryLoader} implementations during
* the resolution process.
* If this parameter is null, the default system class loader
* will be used.
*/
public SchemaFactoryFinder(ClassLoader loader) {
this.classLoader = loader;
if( debug ) {
debugDisplayClassLoader();
}
}
private void debugDisplayClassLoader() {
try {
if( classLoader == SecuritySupport.getContextClassLoader() ) {
debugPrintln("using thread context class loader ("+classLoader+") for search");
return;
}
}
// The VM ran out of memory or there was some other serious problem. Re-throw.
catch (VirtualMachineError vme) {
throw vme;
}
// ThreadDeath should always be re-thrown
catch (ThreadDeath td) {
throw td;
}
catch (Throwable _) {
; // getContextClassLoader() undefined in JDK1.1
}
if( classLoader==ClassLoader.getSystemClassLoader() ) {
debugPrintln("using system class loader ("+classLoader+") for search");
return;
}
debugPrintln("using class loader ("+classLoader+") for search");
}
/**
* Creates a new {@link SchemaFactory} object for the specified
* schema language.
*
* @param schemaLanguage
* See {@link SchemaFactory Schema Language} table in SchemaFactory
* for the list of available schema languages.
*
* @return null if the callee fails to create one.
*
* @throws NullPointerException
* If the schemaLanguage parameter is null.
*/
public SchemaFactory newFactory(String schemaLanguage) {
if(schemaLanguage==null) throw new NullPointerException();
SchemaFactory f = _newFactory(schemaLanguage);
if (debug) {
if (f != null) {
debugPrintln("factory '" + f.getClass().getName() + "' was found for " + schemaLanguage);
} else {
debugPrintln("unable to find a factory for " + schemaLanguage);
}
}
return f;
}
/**
* Lookup a SchemaFactory for the given schemaLanguage.
*
* @param schemaLanguage Schema language to lookup SchemaFactory for.
*
* @return SchemaFactory for the given schemaLanguage.
*/
private SchemaFactory _newFactory(String schemaLanguage) {
SchemaFactory sf;
String propertyName = SERVICE_CLASS.getName() + ":" + schemaLanguage;
// system property look up
try {
if (debug) debugPrintln("Looking up system property '"+propertyName+"'" );
String r = SecuritySupport.getSystemProperty(propertyName);
if (r != null && r.length() > 0) {
if (debug) debugPrintln("The value is '"+r+"'");
sf = createInstance(r);
if(sf!=null) return sf;
}
else if (debug) {
debugPrintln("The property is undefined.");
}
}
// The VM ran out of memory or there was some other serious problem. Re-throw.
catch (VirtualMachineError vme) {
throw vme;
}
// ThreadDeath should always be re-thrown
catch (ThreadDeath td) {
throw td;
}
catch (Throwable t) {
if( debug ) {
debugPrintln("failed to look up system property '"+propertyName+"'" );
t.printStackTrace();
}
}
String javah = SecuritySupport.getSystemProperty( "java.home" );
String configFile = javah + File.separator +
"lib" + File.separator + "jaxp.properties";
String factoryClassName = null ;
// try to read from $java.home/lib/jaxp.properties
try {
if(firstTime){
synchronized(cacheProps){
if(firstTime){
File f=new File( configFile );
firstTime = false;
if(SecuritySupport.doesFileExist(f)){
if (debug) debugPrintln("Read properties file " + f);
cacheProps.load(SecuritySupport.getFileInputStream(f));
}
}
}
}
factoryClassName = cacheProps.getProperty(propertyName);
if (debug) debugPrintln("found " + factoryClassName + " in $java.home/jaxp.properties");
if (factoryClassName != null) {
sf = createInstance(factoryClassName);
if(sf != null){
return sf;
}
}
} catch (Exception ex) {
if (debug) {
ex.printStackTrace();
}
}
/**
// try to read from $java.home/lib/jaxp.properties
try {
String javah = ss.getSystemProperty( "java.home" );
String configFile = javah + File.separator +
"lib" + File.separator + "jaxp.properties";
File f = new File( configFile );
if( ss.doesFileExist(f)) {
sf = loadFromProperty(
propertyName,f.getAbsolutePath(), new FileInputStream(f));
if(sf!=null) return sf;
} else {
debugPrintln("Tried to read "+ f.getAbsolutePath()+", but it doesn't exist.");
}
} catch(Throwable e) {
if( debug ) {
debugPrintln("failed to read $java.home/lib/jaxp.properties");
e.printStackTrace();
}
}
*/
// try META-INF/services files
Iterator sitr = createServiceFileIterator();
while(sitr.hasNext()) {
URL resource = (URL)sitr.next();
if (debug) debugPrintln("looking into " + resource);
try {
sf = loadFromServicesFile(schemaLanguage,resource.toExternalForm(),SecuritySupport.getURLInputStream(resource));
if(sf!=null) return sf;
} catch(IOException e) {
if( debug ) {
debugPrintln("failed to read "+resource);
e.printStackTrace();
}
}
}
// platform defaults
if (schemaLanguage.equals(XMLConstants.W3C_XML_SCHEMA_NS_URI) || schemaLanguage.equals(W3C_XML_SCHEMA10_NS_URI)) {
if (debug) debugPrintln("attempting to use the platform default XML Schema 1.0 validator");
return createInstance("org.apache.xerces.jaxp.validation.XMLSchemaFactory");
}
else if (schemaLanguage.equals(W3C_XML_SCHEMA11_NS_URI)) {
if (debug) debugPrintln("attempting to use the platform default XML Schema 1.1 validator");
return createInstance("org.apache.xerces.jaxp.validation.XMLSchema11Factory");
}
if (debug) debugPrintln("all things were tried, but none was found. bailing out.");
return null;
}
/**
* Creates an instance of the specified and returns it.
*
* @param className
* fully qualified class name to be instantiated.
*
* @return null
* if it fails. Error messages will be printed by this method.
*/
SchemaFactory createInstance( String className ) {
try {
if (debug) debugPrintln("instanciating "+className);
Class clazz;
if( classLoader!=null )
clazz = classLoader.loadClass(className);
else
clazz = Class.forName(className);
if(debug) debugPrintln("loaded it from "+which(clazz));
Object o = clazz.newInstance();
if( o instanceof SchemaFactory )
return (SchemaFactory)o;
if (debug) debugPrintln(className+" is not assignable to "+SERVICE_CLASS.getName());
}
// The VM ran out of memory or there was some other serious problem. Re-throw.
catch (VirtualMachineError vme) {
throw vme;
}
// ThreadDeath should always be re-thrown
catch (ThreadDeath td) {
throw td;
}
catch (Throwable t) {
debugPrintln("failed to instanciate "+className);
if(debug) t.printStackTrace();
}
return null;
}
/** Iterator that lazily computes one value and returns it. */
private static abstract class SingleIterator implements Iterator {
private boolean seen = false;
public final void remove() { throw new UnsupportedOperationException(); }
public final boolean hasNext() { return !seen; }
public final Object next() {
if(seen) throw new NoSuchElementException();
seen = true;
return value();
}
protected abstract Object value();
}
/**
* Returns an {@link Iterator} that enumerates all
* the META-INF/services files that we care.
*/
private Iterator createServiceFileIterator() {
if (classLoader == null) {
return new SingleIterator() {
protected Object value() {
ClassLoader classLoader = SchemaFactoryFinder.class.getClassLoader();
//return (ClassLoader.getSystemResource( SERVICE_ID ));
return SecuritySupport.getResourceAsURL(classLoader, SERVICE_ID);
}
};
} else {
try {
//final Enumeration e = classLoader.getResources(SERVICE_ID);
final Enumeration e = SecuritySupport.getResources(classLoader, SERVICE_ID);
if(debug && !e.hasMoreElements()) {
debugPrintln("no "+SERVICE_ID+" file was found");
}
// wrap it into an Iterator.
return new Iterator() {
public void remove() {
throw new UnsupportedOperationException();
}
public boolean hasNext() {
return e.hasMoreElements();
}
public Object next() {
return e.nextElement();
}
};
} catch (IOException e) {
if (debug) {
debugPrintln("failed to enumerate resources "+SERVICE_ID);
e.printStackTrace();
}
return new ArrayList().iterator(); // empty iterator
}
}
}
/** Searches for a SchemaFactory for a given schema language in a META-INF/services file. */
private SchemaFactory loadFromServicesFile(String schemaLanguage, String resourceName, InputStream in) {
if (debug) debugPrintln("Reading "+resourceName );
// Read the service provider name in UTF-8 as specified in
// the jar spec. Unfortunately this fails in Microsoft
// VJ++, which does not implement the UTF-8
// encoding. Theoretically, we should simply let it fail in
// that case, since the JVM is obviously broken if it
// doesn't support such a basic standard. But since there
// are still some users attempting to use VJ++ for
// development, we have dropped in a fallback which makes a
// second attempt using the platform's default encoding. In
// VJ++ this is apparently ASCII, which is a subset of
// UTF-8... and since the strings we'll be reading here are
// also primarily limited to the 7-bit ASCII range (at
// least, in English versions), this should work well
// enough to keep us on the air until we're ready to
// officially decommit from VJ++. [Edited comment from
// jkesselm]
BufferedReader rd;
try {
rd = new BufferedReader(new InputStreamReader(in, "UTF-8"), DEFAULT_LINE_LENGTH);
} catch (java.io.UnsupportedEncodingException e) {
rd = new BufferedReader(new InputStreamReader(in), DEFAULT_LINE_LENGTH);
}
String factoryClassName = null;
SchemaFactory resultFactory = null;
// See spec for provider-configuration files: http://java.sun.com/j2se/1.5.0/docs/guide/jar/jar.html#Provider%20Configuration%20File
while (true) {
try {
factoryClassName = rd.readLine();
} catch (IOException x) {
// No provider found
break;
}
if (factoryClassName != null) {
// Ignore comments in the provider-configuration file
int hashIndex = factoryClassName.indexOf('#');
if (hashIndex != -1) {
factoryClassName = factoryClassName.substring(0, hashIndex);
}
// Ignore leading and trailing whitespace
factoryClassName = factoryClassName.trim();
// If there's no text left or if this was a blank line, go to the next one.
if (factoryClassName.length() == 0) {
continue;
}
try {
// Found the right SchemaFactory if its isSchemaLanguageSupported(schemaLanguage) method returns true.
SchemaFactory foundFactory = (SchemaFactory) createInstance(factoryClassName);
if (foundFactory.isSchemaLanguageSupported(schemaLanguage)) {
resultFactory = foundFactory;
break;
}
}
catch (Exception e) {}
}
else {
break;
}
}
try {
// try to close the reader.
rd.close();
}
// Ignore the exception.
catch (IOException exc) {}
return resultFactory;
}
private static final Class SERVICE_CLASS = SchemaFactory.class;
private static final String SERVICE_ID = "META-INF/services/" + SERVICE_CLASS.getName();
private static String which( Class clazz ) {
return which( clazz.getName(), clazz.getClassLoader() );
}
/**
* Search the specified classloader for the given classname.
*
* @param classname the fully qualified name of the class to search for
* @param loader the classloader to search
*
* @return the source location of the resource, or null if it wasn't found
*/
private static String which(String classname, ClassLoader loader) {
String classnameAsResource = classname.replace('.', '/') + ".class";
if( loader==null ) loader = ClassLoader.getSystemClassLoader();
//URL it = loader.getResource(classnameAsResource);
URL it = SecuritySupport.getResourceAsURL(loader, classnameAsResource);
if (it != null) {
return it.toString();
} else {
return null;
}
}
}