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/*
* $Id: ClassStuff.java,v 1.1.1.1 2003-02-01 02:10:27 cbj Exp $
* Copyright (C) 2001 David Brownell
*
* This file is part of GNU JAXP, a library.
*
* GNU JAXP is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GNU JAXP is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* As a special exception, if you link this library with other files to
* produce an executable, this library does not by itself cause the
* resulting executable to be covered by the GNU General Public License.
* This exception does not however invalidate any other reasons why the
* executable file might be covered by the GNU General Public License.
*/
package javax.xml.transform;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Method;
import java.util.Properties;
// $Id: ClassStuff.java,v 1.1.1.1 2003-02-01 02:10:27 cbj Exp $
/**
* Package-private utility methods for sharing
* magic related to class loading.
* NOTE: This is cloned in javax.xml.parsers,
* where a different exception is thrown (bleech).
* Keep changes to the two copies in sync.
*
* @author David Brownell
* @version $Id: ClassStuff.java,v 1.1.1.1 2003-02-01 02:10:27 cbj Exp $
*/
final class ClassStuff
{
private ClassStuff () { }
/**
* Get the default factory using the four-stage defaulting
* mechanism defined by JAXP.
*/
static Object
createFactory (String label, String defaultClass)
throws TransformerFactoryConfigurationError
{
String name = null;
ClassLoader loader = null;
// figure out which class loader to use.
// source compiles on jdk 1.1, but works with jdk 1.2+ security
try {
Method m = null;
// Can we use JDK 1.2 APIs? Preferred: security policies apply.
m = Thread.class.getMethod ("getContextClassLoader", null);
loader = (ClassLoader) m.invoke (Thread.currentThread(), null);
} catch (NoSuchMethodException e) {
// Assume that we are running JDK 1.1; use current ClassLoader
loader = ClassStuff.class.getClassLoader();
} catch (Exception e) {
// "should not happen"
throw new UnknownError (e.getMessage());
}
// 1. Check System Property
// ... normally fails in applet environments
try { name = System.getProperty (label);
} catch (SecurityException e) { /* IGNORE */ }
// 2. Check in $JAVA_HOME/lib/jaxp.properties
try {
if (name == null) {
String javaHome;
File file;
javaHome = System.getProperty ("java.home");
file = new File (new File (javaHome, "lib"), "jaxp.properties");
if (file.exists() == true) {
FileInputStream in = new FileInputStream (file);
Properties props = new Properties();
props.load (in);
name = props.getProperty (label);
in.close ();
}
}
} catch (Exception e) { /* IGNORE */ }
// 3. Check Services API
if (name == null) {
try {
String service = "META-INF/services/" + label;
InputStream in;
BufferedReader reader;
if (loader == null)
in = ClassLoader.getSystemResourceAsStream (service);
else
in = loader.getResourceAsStream (service);
if (in != null) {
reader = new BufferedReader (
new InputStreamReader (in, "UTF8"));
name = reader.readLine();
in.close ();
}
} catch (Exception e2) { /* IGNORE */ }
}
// 4. Distro-specific fallback
if (name == null)
name = defaultClass;
// Instantiate!
try {
Class klass;
if (loader == null)
klass = Class.forName (name);
else
klass = loader.loadClass (name);
return klass.newInstance ();
} catch (ClassNotFoundException e) {
throw new TransformerFactoryConfigurationError (e,
"Factory class " + name
+ " not found");
} catch (IllegalAccessException e) {
throw new TransformerFactoryConfigurationError (e,
"Factory class " + name
+ " found but cannot be loaded");
} catch (InstantiationException e) {
throw new TransformerFactoryConfigurationError (e,
"Factory class " + name
+ " loaded but cannot be instantiated"
+ " ((no default constructor?)");
}
}
}
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