01: // NewInstance.java - create a new instance of a class by name.
02: // http://www.saxproject.org
03: // Written by Edwin Goei, edwingo@apache.org
04: // and by David Brownell, dbrownell@users.sourceforge.net
05: // NO WARRANTY! This class is in the Public Domain.
06: // $Id: NewInstance.java,v 1.5 2002/02/01 20:06:20 db Exp $
07:
08: package org.xml.sax.helpers;
09:
10: import java.lang.reflect.Method;
11: import java.lang.reflect.InvocationTargetException;
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: Class driverClass;
45: if (classLoader == null) {
46: driverClass = Class.forName(className);
47: } else {
48: driverClass = classLoader.loadClass(className);
49: }
50: return driverClass.newInstance();
51: }
52:
53: /**
54: * Figure out which ClassLoader to use. For JDK 1.2 and later use
55: * the context ClassLoader.
56: */
57: static ClassLoader getClassLoader() {
58: Method m = null;
59:
60: try {
61: m = Thread.class.getMethod("getContextClassLoader", null);
62: } catch (NoSuchMethodException e) {
63: // Assume that we are running JDK 1.1, use the current ClassLoader
64: return NewInstance.class.getClassLoader();
65: }
66:
67: try {
68: return (ClassLoader) m.invoke(Thread.currentThread(), null);
69: } catch (IllegalAccessException e) {
70: // assert(false)
71: throw new UnknownError(e.getMessage());
72: } catch (InvocationTargetException e) {
73: // assert(e.getTargetException() instanceof SecurityException)
74: throw new UnknownError(e.getMessage());
75: }
76: }
77: }
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