Struts example source code file (RestActionSupport.java)

This example Struts source code file (RestActionSupport.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

defaulthttpheaders, defaulthttpheaders, delete, divider, divider, get, http, httpheaders, method, options, options, post, put, reflection, request, response, servlet, string, string

The Struts RestActionSupport.java source code

/*
 * $Id$
 *
 * 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.struts2.rest;

import java.lang.reflect.Method;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionSupport;

/**
 * Extends {@link ActionSupport} to provides a default implementation of the index method that can be invoked for
 * unknown actions by the {@link com.opensymphony.xwork2.UnknownHandler}.
 */
public class RestActionSupport extends ActionSupport {

	private static final long serialVersionUID = -889518620073576882L;
	
	private static final String DELETE = "DELETE";
	private static final String PUT = "PUT";
	private static final String POST = "POST";
	private static final String GET = "GET";
	private static final String OPTIONS = "OPTIONS";
	private static final String DIVIDER = ", ";

	/**
	 * Default execution.
	 * @return object because it can return string, result or httpHeader.
	 * @throws Exception
	 */
    public Object index() throws Exception {
        return execute();
    }
    
	/**
	 * Inspect the implemented methods to know the allowed http methods.
	 * 
	 * @return Include the header "Allow" with the allowed http methods. 
	 */
    public HttpHeaders options() {
    	
    	String methods = OPTIONS;
    	
    	Method[] meths = this.getClass().getDeclaredMethods();
    	for (Method m : meths) {
    		String methodName = m.getName();
    		if (!methods.contains(GET) &&
    				(methodName.equals("index")
    				|| methodName.equals("show")
    				|| methodName.equals("edit")
    				|| methodName.equals("editNew"))) {
    			methods += DIVIDER + GET;
    		} else if (methodName.equals("create")) {
    			methods += DIVIDER + POST;
    		} else if (methodName.equals("update")) {
    			methods += DIVIDER + PUT;
    		}else if (methodName.equals("destroy")) {
    			methods += DIVIDER + DELETE;
    		}
    	}
    	
    	HttpServletRequest request = ServletActionContext.getRequest();
    	HttpServletResponse response = ServletActionContext.getResponse();
    	response.addHeader("Allow", methods);
    	
    	DefaultHttpHeaders httpHeaders = new DefaultHttpHeaders();
    	httpHeaders.apply(request, response, this);
    	httpHeaders.disableCaching().withStatus(HttpServletResponse.SC_OK);
    	
    	return httpHeaders;
	}
    
    /**
     * By default, return continue.
     * Is possible override the method to return expectation failed.
     * 
     * @return continue
     */
    public HttpHeaders createContinue() {
		return new DefaultHttpHeaders()
		    .disableCaching()
		    .withStatus(HttpServletResponse.SC_CONTINUE);
	}
    
    /**
     * By default, return continue.
     * Is possible override the method to return expectation failed.
     * 
     * @return continue
     */
    public HttpHeaders updateContinue() {
		return new DefaultHttpHeaders()
		    .disableCaching()
		    .withStatus(HttpServletResponse.SC_CONTINUE);
	}
}