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From d..@apache.org
Subject cvs commit: jakarta-velocity/src/java/org/apache/velocity/util/introspection Introspector.java
Date Tue, 11 Sep 2001 17:14:03 GMT
dlr         01/09/11 10:14:03

  Modified:    src/java/org/apache/velocity/util/introspection
                        Introspector.java
  Log:
  JavaDoc improvements.
  
  Revision  Changes    Path
  1.12      +207 -1    jakarta-velocity/src/java/org/apache/velocity/util/introspection/Introspector.java
  
  Index: Introspector.java
  ===================================================================
  RCS file: /home/cvs/jakarta-velocity/src/java/org/apache/velocity/util/introspection/Introspector.java,v
  retrieving revision 1.11
  retrieving revision 1.12
  diff -u -u -r1.11 -r1.12
  --- Introspector.java	2001/09/10 10:36:09	1.11
  +++ Introspector.java	2001/09/11 17:14:03	1.12
  @@ -1 +1,207 @@
  -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.*;

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:jvanzyl@periapt.com">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: 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);
    }
}

  \ No newline at end of file
  +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.*;
  +
  +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:jvanzyl@periapt.com">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: Introspector.java,v 1.12 2001/09/11 17:14:03 dlr Exp $
  + */
  +public class Introspector
  +{
  +    private RuntimeServices rsvc = null;
  +
  +    /**
  +     * Holds the method maps for the classes we know about, keyed by
  +     * Class object.
  +     */ 
  +    private final Map classMethodMaps = new HashMap();
  +    
  +    /**
  +     * Holds the qualified class name to Class object mapping.
  +     */
  +    private final Map classByName = new HashMap();
  +
  +    /**
  +     *  Recieves our RuntimeServices object
  +     */
  +    public void init( RuntimeServices r )
  +    {
  +        this.rsvc = r;
  +    }
  +   
  +    /**
  +     * 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)
  +            {
  +                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);
  +    }
  +}
  
  
  

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