| /* |
| * $Id$ |
| * |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.apache.struts.dispatcher; |
| |
| import org.apache.struts.chain.contexts.ActionContext; |
| |
| /** |
| * This abstract class is a template for choosing the target method based on a |
| * servlet request parameter. |
| * |
| * @version $Rev$ |
| * @since Struts 1.4 |
| */ |
| public abstract class AbstractParameterDispatcher extends AbstractDispatcher { |
| |
| /** |
| * The default parameter name if no parameter is set. |
| * |
| * @see #getDefaultParameterName() |
| */ |
| protected static final String DEFAULT_PARAMETER_NAME = "method"; |
| |
| /** |
| * Retrieves the name of the parameter to fallback upon if the action |
| * configuration did not set the <code>parameter</code> attribute. The |
| * default implementation returns {@value #DEFAULT_PARAMETER_NAME}. |
| * |
| * @return the fallback parameter name; can be <code>null</code> |
| * @see #DEFAULT_PARAMETER_NAME |
| * @see #getParameter(ActionContext) |
| */ |
| protected String getDefaultParameterName() { |
| return DEFAULT_PARAMETER_NAME; |
| } |
| |
| /** |
| * Retrieves the parameter name whose value will identity the intended |
| * method to dispatch. The value is not necessarily a method name, but a key |
| * that can resolve to one. The default implementation returns the mapping's |
| * <code>parameter</code> attribute; otherwise fallback to the default |
| * parameter name. |
| * |
| * @param context the current action context |
| * @return the mapping's parameter name |
| * @see #getDefaultParameterName() |
| */ |
| protected String getParameter(ActionContext context) { |
| String parameter = context.getActionConfig().getParameter(); |
| if ((parameter != null) && (parameter.trim().length() > 0)) { |
| return parameter; |
| } |
| return getDefaultParameterName(); |
| } |
| |
| protected final String resolveMethodName(ActionContext context) { |
| String parameter = getParameter(context); |
| if ("".equals(parameter)) { |
| parameter = null; |
| } |
| |
| if (parameter != null) { |
| return resolveParameterValue(context, parameter); |
| } |
| |
| return null; |
| } |
| |
| /** |
| * Extracts the value that is keyed by the specified parameter. |
| * |
| * @param context the current action context |
| * @param parameter the parameter name |
| * @return the parameter value |
| */ |
| protected abstract String resolveParameterValue(ActionContext context, String parameter); |
| |
| } |