Struts example source code file (Restful2ActionMapper.java)

This example Struts source code file (Restful2ActionMapper.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Struts tags/keywords

actionmapping, configurationmanager, hashmap, hashmap, http_method_param, net, network, object, object, request, response, restful2actionmapper, servlet, string, string, stringtokenizer, unable, utf-8, utf-8, util

The Struts Restful2ActionMapper.java source code

/*
 * $Id: Restful2ActionMapper.java 768855 2009-04-27 02:09:35Z wesw $
 *
 * 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.struts2.dispatcher.mapper;

import java.net.URLDecoder;
import java.util.HashMap;
import java.util.StringTokenizer;

import javax.servlet.http.HttpServletRequest;

import org.apache.struts2.StrutsConstants;

import com.opensymphony.xwork2.config.ConfigurationManager;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;

/**
 * <!-- START SNIPPET: description -->
 *
 * Improved restful action mapper that adds several ReST-style improvements to
 * action mapping, but supports fully-customized URL's via XML.  The two primary
 * ReST enhancements are:
 * <ul>
 *  <li>If the method is not specified (via '!' or 'method:' prefix), the method is
 *      "guessed" at using ReST-style conventions that examine the URL and the HTTP
 *      method.</li>
 *  <li>Parameters are extracted from the action name, if parameter name/value pairs
 *      are specified using PARAM_NAME/PARAM_VALUE syntax.
 * </ul>
 * <p>
 * These two improvements allow a GET request for 'category/action/movie/Thrillers' to
 * be mapped to the action name 'movie' with an id of 'Thrillers' with an extra parameter
 * named 'category' with a value of 'action'.  A single action mapping can then handle
 * all CRUD operations using wildcards, e.g.
 * </p>
 * <pre>
 *   <action name="movie/*" className="app.MovieAction">
 *     <param name="id">{0}</param>
 *     ...
 *   </action>
 * </pre>
 * <p>
 *   This mapper supports the following parameters:
 * </p>
 * <ul>
 *   <li>struts.mapper.idParameterName - If set, this value will be the name
 *       of the parameter under which the id is stored.  The id will then be removed
 *       from the action name.  This allows restful actions to not require wildcards.
 *   </li>
 * </ul>
 * <p>
 * The following URL's will invoke its methods:
 * </p>
 * <ul> 
 *  <li>GET:    /movie/               => method="index"
 *  <li>GET:    /movie/Thrillers      => method="view", id="Thrillers"
 *  <li>GET:    /movie/Thrillers!edit => method="edit", id="Thrillers"
 *  <li>GET:    /movie/new            => method="editNew"
 *  <li>POST:   /movie/               => method="create"
 *  <li>PUT:    /movie/Thrillers      => method="update", id="Thrillers"
 *  <li>DELETE: /movie/Thrillers      => method="remove", id="Thrillers"
 * </ul>
 * <p>
 * To simulate the HTTP methods PUT and DELETE, since they aren't supported by HTML,
 * the HTTP parameter "__http_method" will be used.
 * </p>
 * <p>
 * The syntax and design for this feature was inspired by the ReST support in Ruby on Rails.
 * See <a href="http://ryandaigle.com/articles/2006/08/01/whats-new-in-edge-rails-simply-restful-support-and-how-to-use-it">
 * http://ryandaigle.com/articles/2006/08/01/whats-new-in-edge-rails-simply-restful-support-and-how-to-use-it
 * </a>
 * </p>
 *
 * <!-- END SNIPPET: description -->
 */
public class Restful2ActionMapper extends DefaultActionMapper {

    protected static final Logger LOG = LoggerFactory.getLogger(Restful2ActionMapper.class);
    public static final String HTTP_METHOD_PARAM = "__http_method";
    private String idParameterName = null;
    
    public Restful2ActionMapper() {
    	setSlashesInActionNames("true");
    }
    

    /*
    * (non-Javadoc)
    *
    * @see org.apache.struts2.dispatcher.mapper.ActionMapper#getMapping(javax.servlet.http.HttpServletRequest)
    */
    public ActionMapping getMapping(HttpServletRequest request, ConfigurationManager configManager) {
    	if (!isSlashesInActionNames()) {
    		throw new IllegalStateException("This action mapper requires the setting 'slashesInActionNames' to be set to 'true'");
    	}
        ActionMapping mapping = super.getMapping(request, configManager);
        
        if (mapping == null) {
            return null;
        }

        String actionName = mapping.getName();

        String id = null;

        // Only try something if the action name is specified
        if (actionName != null && actionName.length() > 0) {

            int lastSlashPos = actionName.lastIndexOf('/');
            if (lastSlashPos > -1) {
                id = actionName.substring(lastSlashPos+1);
            }


            // If a method hasn't been explicitly named, try to guess using ReST-style patterns
            if (mapping.getMethod() == null) {

                if (lastSlashPos == actionName.length() -1) {

                    // Index e.g. foo/
                    if (isGet(request)) {
                        mapping.setMethod("index");
                        
                    // Creating a new entry on POST e.g. foo/
                    } else if (isPost(request)) {
                        mapping.setMethod("create");
                    }

                } else if (lastSlashPos > -1) {
                    // Viewing the form to create a new item e.g. foo/new
                    if (isGet(request) && "new".equals(id)) {
                        mapping.setMethod("editNew");

                    // Viewing an item e.g. foo/1
                    } else if (isGet(request)) {
                        mapping.setMethod("view");

                    // Removing an item e.g. foo/1
                    } else if (isDelete(request)) {
                        mapping.setMethod("remove");
                    
                    // Updating an item e.g. foo/1    
                    }  else if (isPut(request)) {
                        mapping.setMethod("update");
                    }
                    
                }
                
                if (idParameterName != null && lastSlashPos > -1) {
                	actionName = actionName.substring(0, lastSlashPos);
                }
            }

            if (idParameterName != null && id != null) {
                if (mapping.getParams() == null) {
                    mapping.setParams(new HashMap<String, Object>());
                }
                mapping.getParams().put(idParameterName, id);
            }

            // Try to determine parameters from the url before the action name
            int actionSlashPos = actionName.lastIndexOf('/', lastSlashPos - 1);
            if (actionSlashPos > 0 && actionSlashPos < lastSlashPos) {
                String params = actionName.substring(0, actionSlashPos);
                HashMap<String,String> parameters = new HashMap();
                try {
                    StringTokenizer st = new StringTokenizer(params, "/");
                    boolean isNameTok = true;
                    String paramName = null;
                    String paramValue;

                    while (st.hasMoreTokens()) {
                        if (isNameTok) {
                            paramName = URLDecoder.decode(st.nextToken(), "UTF-8");
                            isNameTok = false;
                        } else {
                            paramValue = URLDecoder.decode(st.nextToken(), "UTF-8");

                            if ((paramName != null) && (paramName.length() > 0)) {
                                parameters.put(paramName, paramValue);
                            }

                            isNameTok = true;
                        }
                    }
                    if (parameters.size() > 0) {
                        if (mapping.getParams() == null) {
                            mapping.setParams(new HashMap<String, Object>());
                        }
                        mapping.getParams().putAll(parameters);
                    }
                } catch (Exception e) {
                    LOG.warn("Unable to determine parameters from the url", e);
                }
                mapping.setName(actionName.substring(actionSlashPos+1));
            }
        }

        return mapping;
    }

    protected boolean isGet(HttpServletRequest request) {
        return "get".equalsIgnoreCase(request.getMethod());
    }

    protected boolean isPost(HttpServletRequest request) {
        return "post".equalsIgnoreCase(request.getMethod());
    }

    protected boolean isPut(HttpServletRequest request) {
        if ("put".equalsIgnoreCase(request.getMethod())) {
            return true;
        } else {
            return isPost(request) && "put".equalsIgnoreCase(request.getParameter(HTTP_METHOD_PARAM));
        }
    }

    protected boolean isDelete(HttpServletRequest request) {
        if ("delete".equalsIgnoreCase(request.getMethod())) {
            return true;
        } else {
            return isPost(request) && "delete".equalsIgnoreCase(request.getParameter(HTTP_METHOD_PARAM));
        }
    }

	public String getIdParameterName() {
		return idParameterName;
	}

	@Inject(required=false,value=StrutsConstants.STRUTS_ID_PARAMETER_NAME)
	public void setIdParameterName(String idParameterName) {
		this.idParameterName = idParameterName;
	}
}