geirm 01/12/05 13:22:10
Added: src/java/org/apache/velocity/util/introspection
IntrospectorBase.java
Log:
This is the Introspector.java renamed in order to remove any velocity
specific imports for reusability.
Revision Changes Path
1.1
jakarta-velocity/src/java/org/apache/velocity/util/introspection/IntrospectorBase.java
Index: IntrospectorBase.java
===================================================================
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.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:[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: IntrospectorBase.java,v 1.1 2001/12/05 21:22:10 geirm 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>.
*
* @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();
}
}
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