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      1 // NewInstance.java - create a new instance of a class by name.
      2 // http://www.saxproject.org
      3 // Written by Edwin Goei, edwingo (at) apache.org
      4 // and by David Brownell, dbrownell (at) users.sourceforge.net
      5 // NO WARRANTY!  This class is in the Public Domain.
      6 // $Id: NewInstance.java,v 1.4 2002/01/30 20:52:27 dbrownell Exp $
      7 
      8 package org.xml.sax.helpers;
      9 
     10 import java.lang.reflect.InvocationTargetException;
     11 import java.lang.reflect.Method;
     12 
     13 /**
     14  * Create a new instance of a class by name.
     15  *
     16  * <blockquote>
     17  * <em>This module, both source code and documentation, is in the
     18  * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
     19  * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
     20  * for further information.
     21  * </blockquote>
     22  *
     23  * <p>This class contains a static method for creating an instance of a
     24  * class from an explicit class name.  It tries to use the thread's context
     25  * ClassLoader if possible and falls back to using
     26  * Class.forName(String).</p>
     27  *
     28  * <p>This code is designed to compile and run on JDK version 1.1 and later
     29  * including versions of Java 2.</p>
     30  *
     31  * @author Edwin Goei, David Brownell
     32  * @version 2.0.1 (sax2r2)
     33  */
     34 class NewInstance {
     35 
     36     /**
     37      * Creates a new instance of the specified class name
     38      *
     39      * Package private so this code is not exposed at the API level.
     40      */
     41     static Object newInstance (ClassLoader classLoader, String className)
     42         throws ClassNotFoundException, IllegalAccessException,
     43             InstantiationException
     44     {
     45         Class driverClass;
     46         if (classLoader == null) {
     47             driverClass = Class.forName(className);
     48         } else {
     49             driverClass = classLoader.loadClass(className);
     50         }
     51         return driverClass.newInstance();
     52     }
     53 
     54     /**
     55      * Figure out which ClassLoader to use.  For JDK 1.2 and later use
     56      * the context ClassLoader.
     57      */
     58     static ClassLoader getClassLoader ()
     59     {
     60         Method m = null;
     61 
     62         try {
     63             m = Thread.class.getMethod("getContextClassLoader");
     64         } catch (NoSuchMethodException e) {
     65             // Assume that we are running JDK 1.1, use the current ClassLoader
     66             return NewInstance.class.getClassLoader();
     67         }
     68 
     69         try {
     70             return (ClassLoader) m.invoke(Thread.currentThread());
     71         } catch (IllegalAccessException e) {
     72             // assert(false)
     73             throw new UnknownError(e.getMessage());
     74         } catch (InvocationTargetException e) {
     75             // assert(e.getTargetException() instanceof SecurityException)
     76             throw new UnknownError(e.getMessage());
     77         }
     78     }
     79 }
     80