static Object createObject(String factoryId,
    String fallbackClassName) throws ObjectFactory.ConfigurationError 
{
    //
    // static methods
    //
        return createObject(factoryId, null, fallbackClassName);
}

Finds the implementation Class object in the specified order. The specified order is the following:
1. query the system property using System.getProperty
2. read META-INF/services/factoryId file
3. use fallback classname

 static Object createObject(String factoryId,
    String propertiesFilename,
    String fallbackClassName) throws ObjectFactory.ConfigurationError 
{
        if (DEBUG) debugPrintln("debug is on");
        ClassLoader cl = findClassLoader();
        // Use the system property first
        try {
            String systemProp = SecuritySupport.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
        }
        // 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 = SecuritySupport.getSystemProperty("java.home");
                propertiesFilename = javah + File.separator +
                    "lib" + File.separator + DEFAULT_PROPERTIES_FILENAME;
                propertiesFile = new File(propertiesFilename);
                propertiesFileExists = SecuritySupport.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 = SecuritySupport.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 = SecuritySupport.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 = SecuritySupport.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 = SecuritySupport.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);
}

Finds the implementation Class object in the specified order. The specified order is the following:
1. query the system property using System.getProperty
2. read $java.home/lib/propertiesFilename file
3. read META-INF/services/factoryId file
4. use fallback classname

 static ClassLoader findClassLoader() throws ObjectFactory.ConfigurationError 
{
        // Figure out which ClassLoader to use for loading the provider
        // class.  If there is a Context ClassLoader then use it.
        ClassLoader context = SecuritySupport.getContextClassLoader();
        ClassLoader system = SecuritySupport.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 = SecuritySupport.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 = SecuritySupport.getParentClassLoader(chain);
        };
        // Assert: Context ClassLoader not in chain of
        // boot/extension/system ClassLoaders
        return context;
}

Figure out which ClassLoader to use. For JDK 1.2 and later use the context ClassLoader.

 static Class findProviderClass(String className,
    ClassLoader cl,
    boolean doFallback) throws ObjectFactory.ConfigurationError, ClassNotFoundException 
{
        //throw security exception if the calling thread is not allowed to access the package
        //restrict the access to package as speicified in java.security policy
        SecurityManager security = System.getSecurityManager();
        if (security != null) {
            final int lastDot = className.lastIndexOf(".");
            String packageName = className;
            if (lastDot != -1) packageName = className.substring(0, lastDot);
            security.checkPackageAccess(packageName);
        }
        Class providerClass;
        if (cl == null) {
            // XXX Use the bootstrap ClassLoader.  There is no way to
            // load a class using the bootstrap ClassLoader that works
            // in both JDK 1.1 and Java 2.  However, this should still
            // work b/c the following should be true:
            //
            // (cl == null) iff current ClassLoader == null
            //
            // Thus Class.forName(String) will use the current
            // ClassLoader which will be the bootstrap ClassLoader.
            providerClass = Class.forName(className);
        } else {
            try {
                providerClass = cl.loadClass(className);
            } catch (ClassNotFoundException x) {
                if (doFallback) {
                    // Fall back to current classloader
                    ClassLoader current = ObjectFactory.class.getClassLoader();
                    if (current == null) {
                        providerClass = Class.forName(className);
                    } else if (cl != current) {
                        cl = current;
                        providerClass = cl.loadClass(className);
                    } else {
                        throw x;
                    }
                } else {
                    throw x;
                }
            }
        }
        return providerClass;
}

Find a Class using the specified ClassLoader

 static Object newInstance(String className,
    ClassLoader cl,
    boolean doFallback) throws ObjectFactory.ConfigurationError 
{
        // assert(className != null);
        try{
            Class providerClass = findProviderClass(className, cl, doFallback);
            Object instance = providerClass.newInstance();
            if (DEBUG) debugPrintln("created new instance of " + providerClass +
                   " using ClassLoader: " + cl);
            return instance;
        } catch (ClassNotFoundException x) {
            throw new ConfigurationError(
                "Provider " + className + " not found", x);
        } catch (Exception x) {
            throw new ConfigurationError(
                "Provider " + className + " could not be instantiated: " + x,
                x);
        }
}

Create an instance of a class using the specified ClassLoader