VideoSvc.java

package org.magnum.mobilecloud.video.controller;

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

import org.magnum.mobilecloud.video.client.VideoSvcApi;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * This simple VideoSvc allows clients to send HTTP POST requests with
 * videos that are stored in memory using a list. Clients can send HTTP GET
 * requests to receive a JSON listing of the videos that have been sent to
 * the controller so far. Stopping the controller will cause it to lose the history of
 * videos that have been sent to it because they are stored in memory.
 * 
 * Notice how much simpler this VideoSvc is than the original VideoServlet?
 * Spring allows us to dramatically simplify our service. Another important
 * aspect of this version is that we have defined a VideoSvcApi that provides
 * strong typing on both the client and service interface to ensure that we
 * don't send the wrong paraemters, etc.
 * 
 * @author jules
 *
 */

// Tell Spring that this class is a Controller that should 
// handle certain HTTP requests for the DispatcherServlet
@Controller
public class VideoSvc implements VideoSvcApi {
	
	// An in-memory list that the servlet uses to store the
	// videos that are sent to it by clients
	private List<Video> videos = new CopyOnWriteArrayList<Video>();

	// Receives POST requests to /video and converts the HTTP
	// request body, which should contain json, into a Video
	// object before adding it to the list. The @RequestBody
	// annotation on the Video parameter is what tells Spring
	// to interpret the HTTP request body as JSON and convert
	// it into a Video object to pass into the method. The
	// @ResponseBody annotation tells Spring to conver the
	// return value from the method back into JSON and put
	// it into the body of the HTTP response to the client.
	//
	// The VIDEO_SVC_PATH is set to "/video" in the VideoSvcApi
	// interface. We use this constant to ensure that the 
	// client and service paths for the VideoSvc are always
	// in synch.
	//
	// For some ways to improve the validation of the data
	// in the Video object, please see this Spring guide:
	// http://docs.spring.io/spring/docs/3.2.x/spring-framework-reference/html/validation.html#validation-beanvalidation
	//
	@RequestMapping(value=VIDEO_SVC_PATH, method=RequestMethod.POST)
	public @ResponseBody boolean addVideo(@RequestBody Video v){
		return videos.add(v);
	}
	
	// Receives GET requests to /video and returns the current
	// list of videos in memory. Spring automatically converts
	// the list of videos to JSON because of the @ResponseBody
	// annotation.
	@RequestMapping(value=VIDEO_SVC_PATH, method=RequestMethod.GET)
	public @ResponseBody List<Video> getVideoList(){
		return videos;
	}

}