Web Socket 사용법

특징

▶ 웹소켓은 full-duplex 통신을 지원

▶ bytes 스트림을 사용하지 않고 오로지 UTF8 포멧의 메시지 스트림만 허용 

▶ 웹소켓은 HTTP를 기반으로 하면서도 HTTP의 문제점을 해결하는 것을 목표

Ajax(Timer) vs WebSocket 비교

▶ Ajax로 만든 웹 페이지 - 서버 측에서 클라이언트로 보낼 수가 없음, 대응책으로 설정 주기마다 데이터를 데이터 갱신

▶ 웹 소켓 - 서버에서도 클라이언트를 인지를 하는 상태이기에 양방향 통신 가능

브라우저 지원

개인적으로는 특성상 꼭 써야하는거 아니라면 브라우저 제약으로 인하여 타이머 선호함

사용법

□ dependency 추가

<dependency>             <groupId>org.springframework</groupId>             <artifactId>spring-websocket</artifactId>             <version>4.0.9.RELEASE</version> </dependency> <dependency>             <groupId>javax.servlet</groupId>             <artifactId>javax.servlet-api</artifactId>             <version>3.0.1</version>             <scope>provided</scope> </dependency>

□ servlet-context 

<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans"          xmlns:mvc="http://www.springframework.org/schema/mvc"           xmlns:context="http://www.springframework.org/schema/context"          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"           xmlns:aop="http://www.springframework.org/schema/aop"          xmlns:p="http://www.springframework.org/schema/p"         xmlns:websocket="http://www.springframework.org/schema/websocket"          xmlns:util="http://www.springframework.org/schema/util"           xmlns:task="http://www.springframework.org/schema/task"          xsi:schemaLocation="http://www.springframework.org/schema/aop                                   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd                                 http://www.springframework.org/schema/mvc                                   http://www.springframework.org/schema/mvc/spring-mvc.xsd                                 http://www.springframework.org/schema/beans                                   http://www.springframework.org/schema/beans/spring-beans.xsd                                         http://www.springframework.org/schema/task                                   http://www.springframework.org/schema/task/spring-task-3.0.xsd                                 http://www.springframework.org/schema/util                                   http://www.springframework.org/schema/util/spring-util-3.1.xsd                                 http://www.springframework.org/schema/websocket                                   http://www.springframework.org/schema/websocket/spring-websocket.xsd                                 http://www.springframework.org/schema/context                                   http://www.springframework.org/schema/context/spring-context.xsd"> (추가) <websocket:handlers>         <websocket:mapping handler="RefreshHandler" path="/permit/RefreshSocket.do" /> </websocket:handlers> <bean id="RefreshHandler" class="com.chience.odin.socket.RefreshSocket" />

□ RefreshSocket Class

public class RefreshSocket extends TextWebSocketHandler implements InitializingBean {     Set<WebSocketSession> Resource_Sesstion= new HashSet<WebSocketSession>();     public RefreshSocket() {         super();     }     @Override // DisConnect     public void afterConnectionClosed(WebSocketSession session, CloseStatus status){         try {             super.afterConnectionClosed(session, status);             System.out.println("remove Session");             StaticSocket.getResource_Sesstion().remove(session);         } catch (Exception e) {             e.printStackTrace();         }             }     @Override // Connect     public void afterConnectionEstablished(WebSocketSession session) throws Exception {         super.afterConnectionEstablished(session);         System.out.println("new Session");         StaticSocket.getResource_Sesstion().add(session);     }     @Override // receive message     public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception {         super.handleMessage(session, message);     }     @Override     public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {     }     @Override     public boolean supportsPartialMessages() {         return super.supportsPartialMessages();     }     public void sendMessage(String message) {              }     @Override     public void afterPropertiesSet() throws Exception {     } }

□ JAVASCRIPT

<script type="text/javascript">      var wsUri = "ws://192.168.0.190:8080/odin/permit/RefreshSocket.do";      websocket = new WebSocket(wsUri);      websocket.onopen = function(evt) {              onOpen(evt)          };          websocket.onmessage = function(evt) {              onMessage(evt)          };          websocket.onerror = function(evt) {              onError(evt)          };      function onOpen(evt) {         console.log("open");      }      function onMessage(evt) {      }      function onError(evt) {          console.log("error");      }      function doSend(message) {      }      function writeToScreen(message) {      } </script>