1 // NewInstance.java - create a new instance of a class by name. 2 // http://www.saxproject.org 3 // Written by Edwin Goei, edwingo@apache.org 4 // and by David Brownell, dbrownell@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 */ newInstance(ClassLoader classLoader, String className)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 */ getClassLoader()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