/** Figure out which ClassLoader to use. For JDK 1.2 and later use the context ClassLoader. */
static ClassLoader findClassLoader() throws ConfigurationError {
SecuritySupport ss = SecuritySupport.getInstance();
// Figure out which ClassLoader to use for loading the provider
// class. If there is a Context ClassLoader then use it.
ClassLoader context = ss.getContextClassLoader();
ClassLoader system = ss.getSystemClassLoader();
ClassLoader chain = system;
while (true) {
if (context == chain) {
// Assert: we are on JDK 1.1 or we have no Context ClassLoader
// or any Context ClassLoader in chain of system classloader
// (including extension ClassLoader) so extend to widest
// ClassLoader (always look in system ClassLoader if Xerces
// is in boot/extension/system classpath and in current
// ClassLoader otherwise); normal classloaders delegate
// back to system ClassLoader first so this widening doesn't
// change the fact that context ClassLoader will be consulted
ClassLoader current = ObjectFactory.class.getClassLoader();
chain = system;
while (true) {
if (current == chain) {
// Assert: Current ClassLoader in chain of
// boot/extension/system ClassLoaders
return system;
}
if (chain == null) {
break;
}
chain = ss.getParentClassLoader(chain);
}
// Assert: Current ClassLoader not in chain of
// boot/extension/system ClassLoaders
return current;
}
if (chain == null) {
// boot ClassLoader reached
break;
}
// Check for any extension ClassLoaders in chain up to
// boot ClassLoader
chain = ss.getParentClassLoader(chain);
}
;
// Assert: Context ClassLoader not in chain of
// boot/extension/system ClassLoaders
return context;
} // findClassLoader():ClassLoader
/*
* Try to find provider using Jar Service Provider Mechanism
*
* @return instance of provider class if found or null
*/
private static Object findJarServiceProvider(String factoryId) throws ConfigurationError {
SecuritySupport ss = SecuritySupport.getInstance();
String serviceId = "META-INF/services/" + factoryId;
InputStream is = null;
// First try the Context ClassLoader
ClassLoader cl = findClassLoader();
is = ss.getResourceAsStream(cl, serviceId);
// If no provider found then try the current ClassLoader
if (is == null) {
ClassLoader current = ObjectFactory.class.getClassLoader();
if (cl != current) {
cl = current;
is = ss.getResourceAsStream(cl, serviceId);
}
}
if (is == null) {
// No provider found
return null;
}
if (DEBUG) debugPrintln("found jar resource=" + serviceId + " using ClassLoader: " + cl);
// 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(is, "UTF-8"), DEFAULT_LINE_LENGTH);
} catch (java.io.UnsupportedEncodingException e) {
rd = new BufferedReader(new InputStreamReader(is), DEFAULT_LINE_LENGTH);
}
String factoryClassName = null;
try {
// XXX Does not handle all possible input as specified by the
// Jar Service Provider specification
factoryClassName = rd.readLine();
} catch (IOException x) {
// No provider found
return null;
} finally {
try {
// try to close the reader.
rd.close();
}
// Ignore the exception.
catch (IOException exc) {
}
}
if (factoryClassName != null && !"".equals(factoryClassName)) {
if (DEBUG) debugPrintln("found in resource, value=" + factoryClassName);
// Note: here we do not want to fall back to the current
// ClassLoader because we want to avoid the case where the
// resource file was found using one ClassLoader and the
// provider class was instantiated using a different one.
return newInstance(factoryClassName, cl, false);
}
// No provider found
return null;
}
/**
* Finds the implementation Class object in the specified order. The specified order is the
* following:
*
* <ol>
* <li>query the system property using <code>System.getProperty</code>
* <li>read <code>$java.home/lib/<i>propertiesFilename</i></code> file
* <li>read <code>META-INF/services/<i>factoryId</i></code> file
* <li>use fallback classname
* </ol>
*
* @return Class object of factory, never null
* @param factoryId Name of the factory to find, same as a property name
* @param propertiesFilename The filename in the $java.home/lib directory of the properties file.
* If none specified, ${java.home}/lib/xerces.properties will be used.
* @param fallbackClassName Implementation class name, if nothing else is found. Use null to mean
* no fallback.
* @exception ObjectFactory.ConfigurationError
*/
static Object createObject(String factoryId, String propertiesFilename, String fallbackClassName)
throws ConfigurationError {
if (DEBUG) debugPrintln("debug is on");
SecuritySupport ss = SecuritySupport.getInstance();
ClassLoader cl = findClassLoader();
// Use the system property first
try {
String systemProp = ss.getSystemProperty(factoryId);
if (systemProp != null) {
if (DEBUG) debugPrintln("found system property, value=" + systemProp);
return newInstance(systemProp, cl, true);
}
} catch (SecurityException se) {
// Ignore and continue w/ next location
}
// JAXP specific change
// always use fallback class to avoid the expense of constantly
// "stat"ing a non-existent "xerces.properties" and jar SPI entry
// see CR 6400863: Expensive creating of SAX parser in Mustang
if (true) {
if (fallbackClassName == null) {
throw new ConfigurationError("Provider for " + factoryId + " cannot be found", null);
}
if (DEBUG) debugPrintln("using fallback, value=" + fallbackClassName);
return newInstance(fallbackClassName, cl, true);
}
// Try to read from propertiesFilename, or $java.home/lib/xerces.properties
String factoryClassName = null;
// no properties file name specified; use $JAVA_HOME/lib/xerces.properties:
if (propertiesFilename == null) {
File propertiesFile = null;
boolean propertiesFileExists = false;
try {
String javah = ss.getSystemProperty("java.home");
propertiesFilename =
javah + File.separator + "lib" + File.separator + DEFAULT_PROPERTIES_FILENAME;
propertiesFile = new File(propertiesFilename);
propertiesFileExists = ss.getFileExists(propertiesFile);
} catch (SecurityException e) {
// try again...
fLastModified = -1;
fXercesProperties = null;
}
synchronized (ObjectFactory.class) {
boolean loadProperties = false;
FileInputStream fis = null;
try {
// file existed last time
if (fLastModified >= 0) {
if (propertiesFileExists
&& (fLastModified < (fLastModified = ss.getLastModified(propertiesFile)))) {
loadProperties = true;
} else {
// file has stopped existing...
if (!propertiesFileExists) {
fLastModified = -1;
fXercesProperties = null;
} // else, file wasn't modified!
}
} else {
// file has started to exist:
if (propertiesFileExists) {
loadProperties = true;
fLastModified = ss.getLastModified(propertiesFile);
} // else, nothing's changed
}
if (loadProperties) {
// must never have attempted to read xerces.properties before (or it's outdeated)
fXercesProperties = new Properties();
fis = ss.getFileInputStream(propertiesFile);
fXercesProperties.load(fis);
}
} catch (Exception x) {
fXercesProperties = null;
fLastModified = -1;
// assert(x instanceof FileNotFoundException
// || x instanceof SecurityException)
// In both cases, ignore and continue w/ next location
} finally {
// try to close the input stream if one was opened.
if (fis != null) {
try {
fis.close();
}
// Ignore the exception.
catch (IOException exc) {
}
}
}
}
if (fXercesProperties != null) {
factoryClassName = fXercesProperties.getProperty(factoryId);
}
} else {
FileInputStream fis = null;
try {
fis = ss.getFileInputStream(new File(propertiesFilename));
Properties props = new Properties();
props.load(fis);
factoryClassName = props.getProperty(factoryId);
} catch (Exception x) {
// assert(x instanceof FileNotFoundException
// || x instanceof SecurityException)
// In both cases, ignore and continue w/ next location
} finally {
// try to close the input stream if one was opened.
if (fis != null) {
try {
fis.close();
}
// Ignore the exception.
catch (IOException exc) {
}
}
}
}
if (factoryClassName != null) {
if (DEBUG) debugPrintln("found in " + propertiesFilename + ", value=" + factoryClassName);
return newInstance(factoryClassName, cl, true);
}
// Try Jar Service Provider Mechanism
Object provider = findJarServiceProvider(factoryId);
if (provider != null) {
return provider;
}
if (fallbackClassName == null) {
throw new ConfigurationError("Provider for " + factoryId + " cannot be found", null);
}
if (DEBUG) debugPrintln("using fallback, value=" + fallbackClassName);
return newInstance(fallbackClassName, cl, true);
} // createObject(String,String,String):Object
