/*
* Copyright 2006-2010 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.batch.item.adapter;
import java.lang.reflect.Method;
import org.springframework.util.ClassUtils;
import org.springframework.util.MethodInvoker;
import org.springframework.util.ReflectionUtils;
/**
* A {@link MethodInvoker} that is a bit relaxed about its arguments. You can
* give it arguments in the wrong order or you can give it too many arguments
* and it will try and find a method that matches a subset.
*
* @author Dave Syer
*
* @since 2.1
*/
public class HippyMethodInvoker extends MethodInvoker {
@Override
protected Method findMatchingMethod() {
String targetMethod = getTargetMethod();
Object[] arguments = getArguments();
int argCount = arguments.length;
Method[] candidates = ReflectionUtils.getAllDeclaredMethods(getTargetClass());
int minTypeDiffWeight = Integer.MAX_VALUE;
Method matchingMethod = null;
Object[] transformedArguments = null;
int transformedArgumentCount = 0;
for (int i = 0; i < candidates.length; i++) {
Method candidate = candidates[i];
if (candidate.getName().equals(targetMethod)) {
Class<?>[] paramTypes = candidate.getParameterTypes();
Object[] candidateArguments = new Object[paramTypes.length];
int assignedParameterCount = 0;
boolean assigned = paramTypes.length==0;
for (int j = 0; j < arguments.length; j++) {
for (int k = 0; k < paramTypes.length; k++) {
// Pick the first assignable of the right type that
// matches this slot and hasn't already been filled...
if (ClassUtils.isAssignableValue(paramTypes[k], arguments[j]) && candidateArguments[k] == null) {
candidateArguments[k] = arguments[j];
assignedParameterCount++;
assigned = true;
break;
}
}
}
if (assigned && paramTypes.length <= argCount) {
int typeDiffWeight = getTypeDifferenceWeight(paramTypes, candidateArguments);
if (typeDiffWeight < minTypeDiffWeight) {
minTypeDiffWeight = typeDiffWeight;
matchingMethod = candidate;
transformedArguments = candidateArguments;
transformedArgumentCount = assignedParameterCount;
}
}
}
}
if (transformedArguments == null) {
throw new IllegalArgumentException("No matching arguments found for method: " + targetMethod);
}
if (transformedArgumentCount < transformedArguments.length) {
throw new IllegalArgumentException("Only " + transformedArgumentCount + " out of "
+ transformedArguments.length + " arguments could be assigned.");
}
setArguments(transformedArguments);
return matchingMethod;
}
}