actionmethodnameresolver.java

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/*
 * Copyright 2002-2004 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 de.mindmatters.faces.spring.context.servlet.controller;

import javax.faces.component.ActionSource;
import javax.faces.context.FacesContext;
import javax.faces.el.MethodBinding;
import javax.faces.event.ActionEvent;
import javax.servlet.http.HttpServletRequest;

import org.springframework.web.servlet.mvc.multiaction.MethodNameResolver;
import org.springframework.web.servlet.mvc.multiaction.NoSuchRequestHandlingMethodException;

import de.mindmatters.faces.application.ActionEventContextHolder;

/**
 * Simple implementation of MethodNameResolver that maps JSF Action outcomes to
 * method names. This class is the default implementation used by the
 * {@link MultiActionEventController} class.
 * 
 * <p>
 * This class invokes the {@link MethodBinding} from the {@link ActionSource}
 * exposed from the current {@link ActionEvent} and maps the evaluated outcome
 * to a method name.
 * </p>
 * 
 * <p>
 * Examples:
 * <ul>
 * <li><code>&lt;h:commandButton action="foo".../&gt;</code> evaluates to
 * method name 'foo'</li>
 * <li><code>&lt;h:commandButton action="#{foo.bar}".../&gt;</code> invokes
 * method bar on object foo and returns an outcome (a String) which will be used
 * as method name</li>
 * </ul>
 * </p>
 * 
 * @author Andreas Kuhrwahl
 * 
 */
public final class ActionMethodNameResolver implements MethodNameResolver {

    /**
     * {@inheritDoc}
     */
    public String getHandlerMethodName(final HttpServletRequest request)
            throws NoSuchRequestHandlingMethodException {
        ActionEvent event = ActionEventContextHolder.getActionEvent();
        if (event == null) {
            throw new NoSuchRequestHandlingMethodException(request);
        }
        String methodName = null;
        MethodBinding mb = ((ActionSource) event.getComponent()).getAction();
        if (mb != null) {
            try {
                methodName = (String) mb.invoke(FacesContext
                        .getCurrentInstance(), null);
            } catch (Exception ex) {
                methodName = null;
            }
        }
        if (methodName == null) {
            throw new NoSuchRequestHandlingMethodException(request);
        }
        return methodName;
    }

}