http://xml.apache.org/xalan-j/: Serializer to write out XML, HTML etc. as a stream of characters from an input DOM or from input SAX events. (The Apache Software Foundation) 
/*
 * 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: ObjectFactory.java 1225583 2011-12-29 16:08:00Z mrglavas $
 */

package org.apache.xpath.functions;

import java.io.InputStream;
import java.io.IOException;
import java.io.File;
import java.io.FileInputStream;

import java.util.Properties;
import java.io.BufferedReader;
import java.io.InputStreamReader;


This class is duplicated for each JAXP subpackage so keep it in sync.
It is package private and therefore is not exposed as part of the JAXP
API.


This code is designed to implement the JAXP 1.1 spec pluggability
feature and is designed to run on JDK version 1.1 and
later, and to compile on JDK 1.2 and onward.  
The code also runs both as part of an unbundled jar file and
when bundled as part of the JDK.


This class was moved from the javax.xml.parsers.ObjectFactory
class and modified to be used as a general utility for creating objects 
dynamically.

Version:$Id: ObjectFactory.java 1225583 2011-12-29 16:08:00Z mrglavas $
/**
 * This class is duplicated for each JAXP subpackage so keep it in sync.
 * It is package private and therefore is not exposed as part of the JAXP
 * API.
 * <p>
 * This code is designed to implement the JAXP 1.1 spec pluggability
 * feature and is designed to run on JDK version 1.1 and
 * later, and to compile on JDK 1.2 and onward.  
 * The code also runs both as part of an unbundled jar file and
 * when bundled as part of the JDK.
 * <p>
 * This class was moved from the <code>javax.xml.parsers.ObjectFactory</code>
 * class and modified to be used as a general utility for creating objects 
 * dynamically.
 *
 * @version $Id: ObjectFactory.java 1225583 2011-12-29 16:08:00Z mrglavas $
 */
final class ObjectFactory {

    //
    // Constants
    //

    // name of default properties file to look for in JDK's jre/lib directory
    private static final String DEFAULT_PROPERTIES_FILENAME =
                                                     "xalan.properties";

    private static final String SERVICES_PATH = "META-INF/services/";

    
Set to true for debugging 
/** Set to true for debugging */
    private static final boolean DEBUG = false;

    
cache the contents of the xalan.properties file.
 Until an attempt has been made to read this file, this will
be null; if the file does not exist or we encounter some other error
during the read, this will be empty.

/** cache the contents of the xalan.properties file.
     *  Until an attempt has been made to read this file, this will
     * be null; if the file does not exist or we encounter some other error
     * during the read, this will be empty.
     */
    private static Properties fXalanProperties = null;

    
Cache the time stamp of the xalan.properties file so
that we know if it's been modified and can invalidate
the cache when necessary.

/***
     * Cache the time stamp of the xalan.properties file so
     * that we know if it's been modified and can invalidate
     * the cache when necessary.
     */
    private static long fLastModified = -1;

    //
    // Public static methods
    //

    
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



Params:
  • factoryId –             Name of the factory to find, same as
                             a property name
  • fallbackClassName –     Implementation class name, if nothing else
                             is found.  Use null to mean no fallback.
Throws:
Returns:instance of factory, never 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>META-INF/services/<i>factoryId</i></code> file
     *  <li>use fallback classname
     * </ol>
     *
     * @return instance of factory, never null
     *
     * @param factoryId             Name of the factory to find, same as
     *                              a property name
     * @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 fallbackClassName)
        throws ConfigurationError {
        return createObject(factoryId, null, fallbackClassName);
    } // createObject(String,String):Object

    
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



Params:
  • factoryId –             Name of the factory to find, same as
                             a property name
  • propertiesFilename – The filename in the $java.home/lib directory
                          of the properties file.  If none specified,
                          ${java.home}/lib/xalan.properties will be used.
  • fallbackClassName –     Implementation class name, if nothing else
                             is found.  Use null to mean no fallback.
Throws:
Returns:instance of factory, never null
/**
     * Finds the implementation Class object in the specified order.  The
     * specified order is the following:
     * <ol>
     *  <li>query the system property using <code>System.getProperty</code>
     *  <li>read <code>$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 instance 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/xalan.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
    {
        Class factoryClass = lookUpFactoryClass(factoryId,
                                                propertiesFilename,
                                                fallbackClassName);

        if (factoryClass == null) {
            throw new ConfigurationError(
                "Provider for " + factoryId + " cannot be found", null);
        }

        try{
            Object instance = factoryClass.newInstance();
            debugPrintln("created new instance of factory " + factoryId);
            return instance;
        } catch (Exception x) {
            throw new ConfigurationError(
                "Provider for factory " + factoryId
                    + " could not be instantiated: " + x, x);
        }
    } // createObject(String,String,String):Object

    
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



Params:
  • factoryId –             Name of the factory to find, same as
                             a property name
  • propertiesFilename – The filename in the $java.home/lib directory
                          of the properties file.  If none specified,
                          ${java.home}/lib/xalan.properties will be used.
  • fallbackClassName –     Implementation class name, if nothing else
                             is found.  Use null to mean no fallback.
Throws:
Returns:Class object of factory, never null
/**
     * Finds the implementation Class object in the specified order.  The
     * specified order is the following:
     * <ol>
     *  <li>query the system property using <code>System.getProperty</code>
     *  <li>read <code>$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/xalan.properties will be used.
     * @param fallbackClassName     Implementation class name, if nothing else
     *                              is found.  Use null to mean no fallback.
     *
     * @exception ObjectFactory.ConfigurationError
     */
    static Class lookUpFactoryClass(String factoryId) 
        throws ConfigurationError
    {
        return lookUpFactoryClass(factoryId, null, null);
    } // lookUpFactoryClass(String):Class

    
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



Params:
  • factoryId –             Name of the factory to find, same as
                             a property name
  • propertiesFilename – The filename in the $java.home/lib directory
                          of the properties file.  If none specified,
                          ${java.home}/lib/xalan.properties will be used.
  • fallbackClassName –     Implementation class name, if nothing else
                             is found.  Use null to mean no fallback.
Throws:
Returns:Class object that provides factory service, never null
/**
     * Finds the implementation Class object in the specified order.  The
     * specified order is the following:
     * <ol>
     *  <li>query the system property using <code>System.getProperty</code>
     *  <li>read <code>$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 that provides factory service, 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/xalan.properties will be used.
     * @param fallbackClassName     Implementation class name, if nothing else
     *                              is found.  Use null to mean no fallback.
     *
     * @exception ObjectFactory.ConfigurationError
     */
    static Class lookUpFactoryClass(String factoryId,
                                           String propertiesFilename,
                                           String fallbackClassName)
        throws ConfigurationError
    {
        String factoryClassName = lookUpFactoryClassName(factoryId,
                                                         propertiesFilename,
                                                         fallbackClassName);
        ClassLoader cl = findClassLoader();

        if (factoryClassName == null) {
            factoryClassName = fallbackClassName;
        }

        // assert(className != null);
        try{
            Class providerClass = findProviderClass(factoryClassName,
                                                    cl,
                                                    true);
            debugPrintln("created new instance of " + providerClass +
                   " using ClassLoader: " + cl);
            return providerClass;
        } catch (ClassNotFoundException x) {
            throw new ConfigurationError(
                "Provider " + factoryClassName + " not found", x);
        } catch (Exception x) {
            throw new ConfigurationError(
                "Provider "+factoryClassName+" could not be instantiated: "+x,
                x);
        }
    } // lookUpFactoryClass(String,String,String):Class

    
Finds the name of the required implementation class 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



Params:
  • factoryId –             Name of the factory to find, same as
                             a property name
  • propertiesFilename – The filename in the $java.home/lib directory
                          of the properties file.  If none specified,
                          ${java.home}/lib/xalan.properties will be used.
  • fallbackClassName –     Implementation class name, if nothing else
                             is found.  Use null to mean no fallback.
Throws:
Returns:name of class that provides factory service, never null
/**
     * Finds the name of the required implementation class in the specified
     * order.  The specified order is the following:
     * <ol>
     *  <li>query the system property using <code>System.getProperty</code>
     *  <li>read <code>$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 name of class that provides factory service, 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/xalan.properties will be used.
     * @param fallbackClassName     Implementation class name, if nothing else
     *                              is found.  Use null to mean no fallback.
     *
     * @exception ObjectFactory.ConfigurationError
     */
    static String lookUpFactoryClassName(String factoryId,
                                                String propertiesFilename,
                                                String fallbackClassName)
    {
        // Use the system property first
        try {
            String systemProp = SecuritySupport.getSystemProperty(factoryId);
            if (systemProp != null) {
                debugPrintln("found system property, value=" + systemProp);
                return systemProp;
            }
        } catch (SecurityException se) {
            // Ignore and continue w/ next location
        }

        // Try to read from propertiesFilename, or
        // $java.home/lib/xalan.properties
        String factoryClassName = null;
        // no properties file name specified; use
        // $JAVA_HOME/lib/xalan.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;
                fXalanProperties = 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;
                                fXalanProperties = 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 xalan.properties
                        // before (or it's outdeated)
                        fXalanProperties = new Properties();
                        fis = SecuritySupport.getFileInputStream(propertiesFile);
                        fXalanProperties.load(fis);
                    }
	        } catch (Exception x) {
	            fXalanProperties = 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(fXalanProperties != null) {
                factoryClassName = fXalanProperties.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) {
            debugPrintln("found in " + propertiesFilename + ", value="
                          + factoryClassName);
            return factoryClassName;
        }

        // Try Jar Service Provider Mechanism
        return findJarServiceProviderName(factoryId);
    } // lookUpFactoryClass(String,String):String

    //
    // Private static methods
    //

    
Prints a message to standard error if debugging is enabled. 
/** Prints a message to standard error if debugging is enabled. */
    private static void debugPrintln(String msg) {
        if (DEBUG) {
            System.err.println("JAXP: " + msg);
        }
    } // debugPrintln(String)

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

/**
     * Figure out which ClassLoader to use.  For JDK 1.2 and later use
     * the context ClassLoader.
     */
    static ClassLoader findClassLoader()
        throws 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 Xalan
                // 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;
    } // findClassLoader():ClassLoader

    
Create an instance of a class using the specified ClassLoader

/**
     * Create an instance of a class using the specified ClassLoader
     */ 
    static Object newInstance(String className, ClassLoader cl,
                                      boolean doFallback)
        throws ConfigurationError
    {
        // assert(className != null);
        try{
            Class providerClass = findProviderClass(className, cl, doFallback);
            Object instance = providerClass.newInstance();
            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);
        }
    }

    
Find a Class using the specified ClassLoader

/**
     * Find a Class using the specified ClassLoader
     */ 
    static Class findProviderClass(String className, ClassLoader cl,
                                           boolean doFallback)
        throws ClassNotFoundException, ConfigurationError
    {   
        //throw security exception if the calling thread is not allowed to access the
        //class. Restrict the access to the package classes as specified in java.security policy.
        SecurityManager security = System.getSecurityManager();
        try{
                if (security != null){
                    final int lastDot = className.lastIndexOf('.');
                    String packageName = className;
                    if (lastDot != -1) packageName = className.substring(0, lastDot);
                    security.checkPackageAccess(packageName);
                 }   
        }catch(SecurityException e){
            throw e;
        }
        
        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 the name of service provider using Jar Service Provider Mechanism

Returns:instance of provider class if found or null
/**
     * Find the name of service provider using Jar Service Provider Mechanism
     *
     * @return instance of provider class if found or null
     */
    private static String findJarServiceProviderName(String factoryId)
    {
        String serviceId = SERVICES_PATH + factoryId;
        InputStream is = null;

        // First try the Context ClassLoader
        ClassLoader cl = findClassLoader();

        is = SecuritySupport.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 = SecuritySupport.getResourceAsStream(cl, serviceId);
            }
        }

        if (is == null) {
            // No provider found
            return null;
        }

        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"));
        } catch (java.io.UnsupportedEncodingException e) {
            rd = new BufferedReader(new InputStreamReader(is));
        }
        
        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)) {
            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 factoryClassName;
        }

        // No provider found
        return null;
    }

    //
    // Classes
    //

    
A configuration error.

/**
     * A configuration error.
     */
    static class ConfigurationError 
        extends Error {
                static final long serialVersionUID = -5782303800588797207L;
        //
        // Data
        //

        
Exception. 
/** Exception. */
        private Exception exception;

        //
        // Constructors
        //

        
Construct a new instance with the specified detail string and
exception.

/**
         * Construct a new instance with the specified detail string and
         * exception.
         */
        ConfigurationError(String msg, Exception x) {
            super(msg);
            this.exception = x;
        } // <init>(String,Exception)

        //
        // Public methods
        //

        
Returns the exception associated to this error. 
/** Returns the exception associated to this error. */
        Exception getException() {
            return exception;
        } // getException():Exception

    } // class ConfigurationError

} // class ObjectFactory