ObjectMethodAccessor.java

//--------------------------------------------------------------------------
//	Copyright (c) 1998-2004, Drew Davidson and Luke Blanshard
//  All rights reserved.
//
//	Redistribution and use in source and binary forms, with or without
//  modification, are permitted provided that the following conditions are
//  met:
//
//	Redistributions of source code must retain the above copyright notice,
//  this list of conditions and the following disclaimer.
//	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.
//	Neither the name of the Drew Davidson nor the names of its contributors
//  may be used to endorse or promote products derived from this software
//  without specific prior written permission.
//
//	THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
//  "AS IS" AND ANY EXPRESS 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
//  COPYRIGHT OWNER OR 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.
//--------------------------------------------------------------------------
package ariba.util.expr;

import ariba.util.fieldtype.TypeInfo;
import ariba.util.fieldtype.TypeRetriever;
import ariba.util.fieldtype.JavaTypeRegistry;
import ariba.util.fieldtype.JavaTypeProvider;
import ariba.util.fieldtype.MethodInfo;
import ariba.util.fieldtype.NullTypeInfo;
import ariba.util.core.ListUtil;
import ariba.util.core.ArrayUtil;
import ariba.util.core.Assert;

import java.util.*;
import java.lang.reflect.Method;

/**
 * Implementation of PropertyAccessor that uses reflection on the target object's class to
 * find a field or a pair of set/get methods with the given property name.
 * @author Luke Blanshard (blanshlu@netscape.net)
 * @author Drew Davidson (drew@ognl.org)
 */
public class ObjectMethodAccessor implements MethodAccessor
{
        /* MethodAccessor interface */
    public Object callStaticMethod( Map context, Class targetClass, String methodName, Object[] args ) throws MethodFailedException
    {
        List methods = getAppropriateMethod(targetClass, methodName, args, true);
        return ExprRuntime.callAppropriateMethod( (ExprContext)context, targetClass, null, methodName, null, methods, args );
    }

    public Object callMethod( Map context, Object target, String methodName, Object[] args ) throws MethodFailedException
    {
        Class       targetClass = (target == null) ? null : target.getClass();
        List methods = getAppropriateMethod(targetClass, methodName, args, false);
        return ExprRuntime.callAppropriateMethod( (ExprContext)context, target, target, methodName, null, methods, args );
    }

    private List<Method> getAppropriateMethod (Class targetClass,
                                               String methodName,
                                               Object[] args,
                                               boolean isStatic)
    {
        if (targetClass == null) {
            return null;
        }

        String className = targetClass.getName();
        List <TypeInfo> argTypes = getArgumentTypes(args);
        TypeRetriever retriever = JavaTypeRegistry.instance();
        TypeInfo targetType = retriever.getTypeInfo(className);

        // In the case of nested class loaders we could have a class for which
        // classForName() (using the system class loader) might fail,
        // so we look up using the class explicitly
        // Todo: reconsider the getTypeInfo interface: maybe add class as an (optional) arg
        if (targetType == null) {
            targetType = ((JavaTypeProvider)JavaTypeProvider.instance()).getTypeInfo(targetClass);
        }
        
        if (targetType instanceof JavaTypeProvider.JavaTypeInfo) {
            JavaTypeProvider.JavaTypeInfo javaType =
                    (JavaTypeProvider.JavaTypeInfo)targetType;

             MethodInfo methodInfo = javaType.getMethod(
                     retriever, methodName, argTypes, isStatic);
            if (methodInfo != null &&
                methodInfo instanceof JavaTypeProvider.JavaMethodInfo)
            {
                return ListUtil.list(((JavaTypeProvider.JavaMethodInfo)methodInfo).getMethod());
            }
        }

        return null;
    }

    private List <TypeInfo> getArgumentTypes (Object[] args)
    {
        TypeRetriever retriever = JavaTypeRegistry.instance();
        List result = ListUtil.list();
        if (!ArrayUtil.nullOrEmptyArray(args)) {
            for (int i=0; i < args.length; i++) {
                Object arg = args[i];
                TypeInfo type = NullTypeInfo.instance;

                if (arg != null) {
                    Class argCls = arg.getClass();
                    type = retriever.getTypeInfo(argCls.getName());
                    Assert.that(type != null,
                            "Fail to retrieve type for name '%s'.", argCls.getName());
                }

                result.add(type);
            }
        }
        return result;
    }
}