1 /* 2 * $Id$ 3 * 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, 15 * software distributed under the License is distributed on an 16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 17 * KIND, either express or implied. See the License for the 18 * specific language governing permissions and limitations 19 * under the License. 20 */ 21 package org.apache.struts.dispatcher; 22 23 import java.lang.reflect.Method; 24 25 import org.apache.struts.action.Action; 26 import org.apache.struts.chain.contexts.ActionContext; 27 28 /** 29 * This abstract class is the stock template for resolving methods for a 30 * {@link Dispatcher}. The implementation handles methods that accept no 31 * arguments or only an {@link ActionContext} instance: 32 * <ul> 33 * <li><code><i>return_type</i> execute()</code></li> 34 * <li><code><i>return_type</i> execute(ActionContext context)</code></li> 35 * </ul> 36 * 37 * @version $Rev$ 38 * @since Struts 1.4 39 */ 40 public abstract class AbstractMethodResolver implements MethodResolver { 41 private static final long serialVersionUID = -9045373032747695495L; 42 43 /** 44 * The argument listing for a method without arguments. 45 * 46 * @see #EMPTY_ARGUMENT_TYPES 47 */ 48 protected static final Object[] EMPTY_ARGUMENTS = {}; 49 50 /** 51 * The type listing used for a method without arguments. 52 * 53 * @see #EMPTY_ARGUMENTS 54 */ 55 protected static final Class<?>[] EMPTY_ARGUMENT_TYPES = {}; 56 57 /** 58 * The argument listing for a method accepting the {@link ActionContext}. 59 */ 60 private static final Class<?>[] ACTION_CONTEXT_ARGUMENT_TYPES = { ActionContext.class }; 61 62 public Object[] buildArguments(ActionContext context, Method method) { 63 Class<?>[] parameterTypes = method.getParameterTypes(); 64 switch (parameterTypes.length) { 65 case 0: 66 return EMPTY_ARGUMENTS; 67 68 case 1: 69 if (parameterTypes[0].isInstance(context)) { 70 return new Object[] { context }; 71 } 72 return null; 73 74 default: 75 return null; 76 } 77 } 78 79 public Method resolveMethod(ActionContext context, String methodName) throws NoSuchMethodException { 80 Class<? extends Action> actionClass = context.getAction().getClass(); 81 82 // Does the method accept nothing? 83 try { 84 return actionClass.getMethod(methodName, EMPTY_ARGUMENT_TYPES); 85 } catch (NoSuchMethodException e) { 86 // continue 87 } 88 89 // Does the method accept the action context? 90 return actionClass.getMethod(methodName, ACTION_CONTEXT_ARGUMENT_TYPES); 91 } 92 93 }