// $Id: SchemaFactoryFinder.java,v 1.14 2004/11/24 23:32:37 jsuttor Exp $ /* * @(#)SchemaFactoryFinder.java 1.12 05/01/04 * * Copyright 2005 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. * */ package javax.xml.validation; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.net.URL; import java.util.ArrayList; import java.util.Enumeration; import java.util.Iterator; import java.util.NoSuchElementException; import java.util.Properties; /** * Implementation of {@link SchemaFactory#newInstance(String)}. * * @author Kohsuke Kawaguchi * @version $Revision: 1.14 $, $Date: 2004/11/24 23:32:37 $ * @since 1.5 */ class SchemaFactoryFinder { /** debug support code. */ private static boolean debug = false; /** *
Take care of restrictions imposed by java security model
*/ private static SecuritySupport ss = new SecuritySupport(); /** *Cache properties for performance.
*/ private static Properties cacheProps = new Properties(); /** *First time requires initialization overhead.
*/ private static boolean firstTime = true; static { // Use try/catch block to support applets try { debug = ss.getSystemProperty("jaxp.debug") != null; } 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
.
Constructor that specifies ClassLoader
to use
* to find SchemaFactory
.
Creates a new {@link SchemaFactory} object for the specified * schema language.
* * @param schemaLanguage * See {@link SchemaFactory Schema Language} table inSchemaFactory
* 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 (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
.
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 {
debugPrintln("Looking up system property '"+propertyName+"'" );
String r = ss.getSystemProperty(propertyName);
if(r!=null) {
debugPrintln("The value is '"+r+"'");
sf = createInstance(r);
if(sf!=null) return sf;
} else
debugPrintln("The property is undefined.");
} catch( Throwable t ) {
if( debug ) {
debugPrintln("failed to look up system property '"+propertyName+"'" );
t.printStackTrace();
}
}
String javah = ss.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(ss.doesFileExist(f)){
debugPrintln("Read properties file " + f);
cacheProps.load(ss.getFileInputStream(f));
}
}
}
}
factoryClassName = cacheProps.getProperty(propertyName);
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();
debugPrintln("looking into " + resource);
try {
//sf = loadFromProperty(schemaLanguage,resource.toExternalForm(),resource.openStream());
sf = loadFromProperty(schemaLanguage,resource.toExternalForm(),ss.getURLInputStream(resource));
if(sf!=null) return sf;
} catch(IOException e) {
if( debug ) {
debugPrintln("failed to read "+resource);
e.printStackTrace();
}
}
}
// platform default
if(schemaLanguage.equals("http://www.w3.org/2001/XMLSchema")) {
debugPrintln("attempting to use the platform default XML Schema validator");
return createInstance("com.sun.org.apache.xerces.internal.jaxp.validation.xs.SchemaFactoryImpl");
}
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 instanciated. * * @return null * if it fails. Error messages will be printed by this method. */ private SchemaFactory createInstance( String className ) { try { 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; debugPrintln(className+" is not assignable to "+SERVICE_CLASS.getName()); } 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(); } /** * Looks up a value in a property file * while producing all sorts of debug messages. * * @return null * if there was an error. */ private SchemaFactory loadFromProperty( String keyName, String resourceName, InputStream in ) throws IOException { debugPrintln("Reading "+resourceName ); Properties props=new Properties(); props.load(in); in.close(); String factoryClassName = props.getProperty(keyName); if(factoryClassName != null){ debugPrintln("found "+keyName+" = " + factoryClassName); return createInstance(factoryClassName); } else { debugPrintln(keyName+" is not in the property file"); return null; } } /** * 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 ss.getResourceAsURL(classLoader, SERVICE_ID); } }; } else { try { //final Enumeration e = classLoader.getResources(SERVICE_ID); final Enumeration e = ss.getResources(classLoader, SERVICE_ID); if(!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) { debugPrintln("failed to enumerate resources "+SERVICE_ID); if(debug) e.printStackTrace(); return new ArrayList().iterator(); // empty iterator } } } 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 = ss.getResourceAsURL(loader, classnameAsResource); if (it != null) { return it.toString(); } else { return null; } } }