| 1 | /* |
| 2 | * Copyright 2006-2010 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package org.springframework.batch.item.adapter; |
| 17 | |
| 18 | import java.lang.reflect.Method; |
| 19 | |
| 20 | import org.springframework.util.ClassUtils; |
| 21 | import org.springframework.util.MethodInvoker; |
| 22 | import org.springframework.util.ReflectionUtils; |
| 23 | |
| 24 | /** |
| 25 | * A {@link MethodInvoker} that is a bit relaxed about its arguments. You can |
| 26 | * give it arguments in the wrong order or you can give it too many arguments |
| 27 | * and it will try and find a method that matches a subset. |
| 28 | * |
| 29 | * @author Dave Syer |
| 30 | * |
| 31 | * @since 2.1 |
| 32 | */ |
| 33 | public class HippyMethodInvoker extends MethodInvoker { |
| 34 | |
| 35 | @Override |
| 36 | protected Method findMatchingMethod() { |
| 37 | String targetMethod = getTargetMethod(); |
| 38 | Object[] arguments = getArguments(); |
| 39 | int argCount = arguments.length; |
| 40 | |
| 41 | Method[] candidates = ReflectionUtils.getAllDeclaredMethods(getTargetClass()); |
| 42 | int minTypeDiffWeight = Integer.MAX_VALUE; |
| 43 | Method matchingMethod = null; |
| 44 | |
| 45 | Object[] transformedArguments = null; |
| 46 | int transformedArgumentCount = 0; |
| 47 | |
| 48 | for (int i = 0; i < candidates.length; i++) { |
| 49 | Method candidate = candidates[i]; |
| 50 | if (candidate.getName().equals(targetMethod)) { |
| 51 | Class<?>[] paramTypes = candidate.getParameterTypes(); |
| 52 | Object[] candidateArguments = new Object[paramTypes.length]; |
| 53 | int assignedParameterCount = 0; |
| 54 | boolean assigned = paramTypes.length==0; |
| 55 | for (int j = 0; j < arguments.length; j++) { |
| 56 | for (int k = 0; k < paramTypes.length; k++) { |
| 57 | // Pick the first assignable of the right type that |
| 58 | // matches this slot and hasn't already been filled... |
| 59 | if (ClassUtils.isAssignableValue(paramTypes[k], arguments[j]) && candidateArguments[k] == null) { |
| 60 | candidateArguments[k] = arguments[j]; |
| 61 | assignedParameterCount++; |
| 62 | assigned = true; |
| 63 | break; |
| 64 | } |
| 65 | } |
| 66 | } |
| 67 | if (assigned && paramTypes.length <= argCount) { |
| 68 | int typeDiffWeight = getTypeDifferenceWeight(paramTypes, candidateArguments); |
| 69 | if (typeDiffWeight < minTypeDiffWeight) { |
| 70 | minTypeDiffWeight = typeDiffWeight; |
| 71 | matchingMethod = candidate; |
| 72 | transformedArguments = candidateArguments; |
| 73 | transformedArgumentCount = assignedParameterCount; |
| 74 | } |
| 75 | } |
| 76 | } |
| 77 | } |
| 78 | |
| 79 | if (transformedArguments == null) { |
| 80 | throw new IllegalArgumentException("No matching arguments found for method: " + targetMethod); |
| 81 | } |
| 82 | |
| 83 | if (transformedArgumentCount < transformedArguments.length) { |
| 84 | throw new IllegalArgumentException("Only " + transformedArgumentCount + " out of " |
| 85 | + transformedArguments.length + " arguments could be assigned."); |
| 86 | } |
| 87 | |
| 88 | setArguments(transformedArguments); |
| 89 | return matchingMethod; |
| 90 | |
| 91 | } |
| 92 | } |