| 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 apache@apache.org. |
| * |
| * 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.Map; |
| import java.util.Set; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| |
| import java.lang.reflect.Method; |
| |
| /** |
| * 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:jvanzyl@apache.org">Jason van Zyl</a> |
| * @author <a href="mailto:bob@werken.com">Bob McWhirter</a> |
| * @author <a href="mailto:szegedia@freemail.hu">Attila Szegedi</a> |
| * @author <a href="mailto:paulo.gaspar@krankikom.de">Paulo Gaspar</a> |
| * @version $Id: IntrospectorBase.java,v 1.2 2001/12/05 23:43:55 jvanzyl Exp $ |
| */ |
| public class IntrospectorBase |
| { |
| /** |
| * Holds the method maps for the classes we know about, keyed by |
| * Class object. |
| */ |
| protected Map classMethodMaps = new HashMap(); |
| |
| /** |
| * Holds the qualified class names for the classes |
| * we hold in the classMethodMaps hash |
| */ |
| protected Set cachedClassNames = new HashSet(); |
| |
| /** |
| * Gets the method defined by <code>name</code> and |
| * <code>params</code> for the Class <code>c</code>. |
| * |
| * @param c Class in which the method search is taking place |
| * @param name Name of the method being searched for |
| * @param params An array of Objects (not Classes) that describe the |
| * the parameters |
| * |
| * @return The desired Method object. |
| */ |
| 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) |
| { |
| if ( cachedClassNames.contains( c.getName() )) |
| { |
| /* |
| * we have a map for a class with same name, but not |
| * this class we are looking at. This implies a |
| * classloader change, so dump |
| */ |
| clearCache(); |
| } |
| |
| 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. |
| */ |
| protected ClassMap createClassMap(Class c) |
| { |
| ClassMap classMap = new ClassMap( c ); |
| classMethodMaps.put(c, classMap); |
| cachedClassNames.add( c.getName() ); |
| |
| return classMap; |
| } |
| |
| /** |
| * Clears the classmap and classname |
| * caches |
| */ |
| protected void clearCache() |
| { |
| /* |
| * since we are synchronizing on this |
| * object, we have to clear it rather than |
| * just dump it. |
| */ |
| classMethodMaps.clear(); |
| |
| /* |
| * for speed, we can just make a new one |
| * and let the old one be GC'd |
| */ |
| cachedClassNames = new HashSet(); |
| } |
| } |