package org.apache.velocity.util.introspection; /* * The Apache Software License, Version 1.1 * * Copyright (c) 2001 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, if * any, must include the following acknowlegement: * "This product includes software developed by the * Apache Software Foundation (http://www.apache.org/)." * Alternately, this acknowlegement may appear in the software itself, * if and wherever such third-party acknowlegements normally appear. * * 4. The names "The Jakarta Project", "Velocity", and "Apache Software * Foundation" must not be used to endorse or promote products derived * from this software without prior written permission. For written * permission, please contact [EMAIL PROTECTED] * * 5. Products derived from this software may not be called "Apache" * nor may "Apache" appear in their names without prior written * permission of the Apache Group. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. */ import java.util.*; import java.lang.reflect.Method; import java.lang.reflect.Modifier; import org.apache.velocity.runtime.RuntimeServices; /** * This basic function of this class is to return a Method * object for a particular class given the name of a method * and the parameters to the method in the form of an Object[] * * The first time the Introspector sees a * class it creates a class method map for the * class in question. Basically the class method map * is a Hastable where Method objects are keyed by a * concatenation of the method name and the names of * classes that make up the parameters. * * For example, a method with the following signature: * * public void method(String a, StringBuffer b) * * would be mapped by the key: * * "method" + "java.lang.String" + "java.lang.StringBuffer" * * This mapping is performed for all the methods in a class * and stored for * @author <a href="mailto:[EMAIL PROTECTED]";>Jason van Zyl</a> * @author <a href="mailto:[EMAIL PROTECTED]";>Bob McWhirter</a> * @author <a href="mailto:[EMAIL PROTECTED]";>Attila Szegedi</a> * @author <a href="mailto:[EMAIL PROTECTED]";>Paulo Gaspar</a> * @version $Id: Introspector.java,v 1.11 2001/09/10 10:36:09 geirm Exp $ */ public class Introspector { private RuntimeServices rsvc = null; /* * Holds the method maps for the classes we know about, * keyed by Class */ private final Map classMethodMaps = new HashMap(); /* * Holds the qualified class name to Class mapping */ private final Map classByName = new HashMap(); /** * Recieves our RuntimeServices object */ public void init( RuntimeServices r ) { this.rsvc = r; } public Method getMethod(Class c, String name, Object[] params) throws Exception { if (c == null) { throw new Exception ( "Introspector.getMethod(): Class method key was null: " + name ); } ClassMap classMap = null; synchronized(classMethodMaps) { classMap = (ClassMap)classMethodMaps.get(c); /* * if we don't have this, check to see if we have it * by name. if so, then we have a classloader change * so dump our caches. */ if ( classMap == null) { Class cachedClass = (Class) classByName.get( c.getName() ); if ( cachedClass != null) { clearCache(); rsvc.info("Introspector : detected classloader change. Dumping cache."); } classMap = createClassMap(c); } } return classMap.findMethod(name, params); } /** * Creates a class map for specific class and registers it in the * cache. Also adds the qualified name to the name->class map * for later Classloader change detection. */ private ClassMap createClassMap(Class c) { ClassMap classMap = new ClassMap(c); classMethodMaps.put( c, classMap); classByName.put(c.getName(), c); return classMap; } /** * Clears the classmap and classname * caches */ private void clearCache() { classMethodMaps.clear(); classByName.clear(); } /** * Checks whether the provided object implements a given method. * * * @param object The object to check. * @param methodName The method to check for. * @return Whether the method is implemented. */ public boolean implementsMethod(Object object, String methodName) { int m; Method[] methods = object.getClass().getMethods(); for (m = 0 ; m < methods.length ; ++m) { if (methodName.equals(methods[m].getName())) { break; } } return (m < methods.length); } }
