websocket基於java實現
實現方式
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常用的 Node 實現有以下三種。
/** * 伺服器 * @ClassName: WebSocket * @Description: TODO * @author OnlyMate * @Date 2018年8月16日 下午2:46:54 * */ @ServerEndpoint("/webSocketByTomcat/{username}") public class WebSocket { private static int onlineCount = 0; private static Map<String, WebSocket> clients = new ConcurrentHashMap<String, WebSocket>(); private Session session; private String username; @OnOpen public void onOpen(@PathParam("username") String username, Session session) throws IOException { this.username = username; this.session = session; addOnlineCount(); clients.put(username, this); System.out.println("已連線"); } @OnClose public void onClose() throws IOException { clients.remove(username); subOnlineCount(); } @OnMessage public void onMessage(String message) throws IOException { JSONObject jsonTo = JSONObject.parseObject(message); System.out.println(jsonTo.getString("to") +":"+ jsonTo.getString("msg")); if (!jsonTo.getString("to").toLowerCase().equals("all")){ sendMessageTo(jsonTo.getString("msg"), jsonTo.getString("to")); }else{ sendMessageAll(jsonTo.getString("msg")); } } @OnError public void onError(Session session, Throwable error) { error.printStackTrace(); } public void sendMessageTo(String message, String To) throws IOException { // session.getBasicRemote().sendText(message); //session.getAsyncRemote().sendText(message); for (WebSocket item : clients.values()) { if (item.username.equals(To) ) item.session.getAsyncRemote().sendText(message); } } public void sendMessageAll(String message) throws IOException { for (WebSocket item : clients.values()) { item.session.getAsyncRemote().sendText(message); } } public static synchronized int getOnlineCount() { return onlineCount; } public static synchronized void addOnlineCount() { WebSocket.onlineCount++; } public static synchronized void subOnlineCount() { WebSocket.onlineCount--; } public static synchronized Map<String, WebSocket> getClients() { return clients; } }
客戶端
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt"%> <c:set var="ctx" value="${pageContext.request.contextPath}" /> <c:set var="ctxpath" value="${pageContext.request.scheme}${'://'}${pageContext.request.serverName}${':'}${pageContext.request.serverPort}${pageContext.request.contextPath}" /> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta charset=UTF-8"> <title>登入測試</title> </head> <body> <h2>Hello World!</h2> <div> <span>sessionId:</span> <% HttpSession s= request.getSession(); out.println(s.getId()); %> </div> <input id="sessionId" type="hidden" value="<%=session.getId() %>" /> <input id="text" type="text" /> <button onclick="send()">傳送訊息</button> <hr /> <button onclick="closeWebSocket()">關閉WebSocket連線</button> <hr /> <div id="message"></div> </body> <script type="text/javascript" src="http://localhost:8088/static/js/sockjs-0.3.min.js"></script> <script type="text/javascript"> var websocket = null; if('WebSocket' in window) { websocket = new WebSocket("ws://localhost:8088/websocket/webSocketByTomcat/"+document.getElementById('sessionId').value); } else if('MozWebSocket' in window) { websocket = new MozWebSocket("ws://localhost:8088/websocket/webSocketByTomcat/"+document.getElementById('sessionId').value); } else { websocket = new SockJS("localhost:8088/websocket/webSocketByTomcat/"+document.getElementById('sessionId').value); } //連線發生錯誤的回撥方法 websocket.onerror = function () { setMessageInnerHTML("WebSocket連線發生錯誤"); }; //連線成功建立的回撥方法 websocket.onopen = function () { setMessageInnerHTML("WebSocket連線成功"); } //接收到訊息的回撥方法 websocket.onmessage = function (event) { setMessageInnerHTML(event.data); } //連線關閉的回撥方法 websocket.onclose = function () { setMessageInnerHTML("WebSocket連線關閉"); } //監聽視窗關閉事件,當視窗關閉時,主動去關閉websocket連線,防止連線還沒斷開就關閉視窗,server端會拋異常。 window.onbeforeunload = function () { closeWebSocket(); } //將訊息顯示在網頁上 function setMessageInnerHTML(innerHTML) { document.getElementById('message').innerHTML += innerHTML + '<br/>'; } //關閉WebSocket連線 function closeWebSocket() { websocket.close(); } //傳送訊息 function send() { var message = document.getElementById('text').value; websocket.send(message); } </script> </html>
注意匯入socketjs時要使用地址全稱,並且連線使用的是http而不是websocket的ws
服務端如何向客戶端推送訊息呢?
程式碼如下
/** * 服務端推送訊息對客戶端 * @ClassName: ServiceClientController * @Description: TODO * @author OnlyMate * @Date 2018年8月16日 下午2:45:22 * */ @Controller @RequestMapping(value="webSocketByTomcat/serviceToClient") public class ServiceClientByTomcatController { private WebSocket websocket = new WebSocket(); @RequestMapping public void sendMsg(HttpServletRequest request, HttpServletResponse response) throws IOException { JSONObject json = new JSONObject(); json.put("to", request.getSession().getId()); json.put("msg", "歡迎連線WebSocket!!!!"); websocket.onMessage(json.toJSONString()); } }
效果如下圖所示
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spring整合websocket方法
springboot對websocket支援很友好,只需要繼承webSocketHandler類,重寫幾個方法就可以了
這個類是對訊息的一些處理,比如是發給一個人,還是發給所有人,並且前端連線時觸發的一些動作
/** * 建立一個WebSocket server * * @ClassName: CustomWebSocketHandler * @Description: TODO * @author OnlyMate * @Date 2018年8月16日 下午3:17:34 * */ @Service public class CustomWebSocketHandler extends TextWebSocketHandler implements WebSocketHandler { private Logger logger = LoggerFactory.getLogger(CustomWebSocketHandler.class); // 線上使用者列表 private static final Map<String, WebSocketSession> users; // 使用者標識 private static final String CLIENT_ID = "mchNo"; static { users = new HashMap<>(); } @Override public void afterConnectionEstablished(WebSocketSession session) throws Exception { logger.info("成功建立websocket-spring連線"); String mchNo = getMchNo(session); if (StringUtils.isNotEmpty(mchNo)) { users.put(mchNo, session); session.sendMessage(new TextMessage("成功建立websocket-spring連線")); logger.info("使用者標識:{},Session:{}", mchNo, session.toString()); } } @Override public void handleTextMessage(WebSocketSession session, TextMessage message) { logger.info("收到客戶端訊息:{}", message.getPayload()); JSONObject msgJson = JSONObject.parseObject(message.getPayload()); String to = msgJson.getString("to"); String msg = msgJson.getString("msg"); WebSocketMessage<?> webSocketMessageServer = new TextMessage("server:" +message); try { session.sendMessage(webSocketMessageServer); if("all".equals(to.toLowerCase())) { sendMessageToAllUsers(new TextMessage(getMchNo(session) + ":" +msg)); }else { sendMessageToUser(to, new TextMessage(getMchNo(session) + ":" +msg)); } } catch (IOException e) { logger.info("handleTextMessage method error:{}", e); } } @Override public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception { if (session.isOpen()) { session.close(); } logger.info("連接出錯"); users.remove(getMchNo(session)); } @Override public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception { logger.info("連線已關閉:" + status); users.remove(getMchNo(session)); } @Override public boolean supportsPartialMessages() { return false; } public void sendMessage(String jsonData) { logger.info("收到客戶端訊息sendMessage:{}", jsonData); JSONObject msgJson = JSONObject.parseObject(jsonData); String mchNo = StringUtils.isEmpty(msgJson.getString(CLIENT_ID)) ? "陌生人" : msgJson.getString(CLIENT_ID); String to = msgJson.getString("to"); String msg = msgJson.getString("msg"); if("all".equals(to.toLowerCase())) { sendMessageToAllUsers(new TextMessage(mchNo + ":" +msg)); }else { sendMessageToUser(to, new TextMessage(mchNo + ":" +msg)); } } /** * 傳送資訊給指定使用者 * @Title: sendMessageToUser * @Description: TODO * @Date 2018年8月21日 上午11:01:08 * @author OnlyMate * @param mchNo * @param message * @return */ public boolean sendMessageToUser(String mchNo, TextMessage message) { if (users.get(mchNo) == null) return false; WebSocketSession session = users.get(mchNo); logger.info("sendMessage:{} ,msg:{}", session, message.getPayload()); if (!session.isOpen()) { logger.info("客戶端:{},已斷開連線,傳送訊息失敗", mchNo); return false; } try { session.sendMessage(message); } catch (IOException e) { logger.info("sendMessageToUser method error:{}", e); return false; } return true; } /** * 廣播資訊 * @Title: sendMessageToAllUsers * @Description: TODO * @Date 2018年8月21日 上午11:01:14 * @author OnlyMate * @param message * @return */ public boolean sendMessageToAllUsers(TextMessage message) { boolean allSendSuccess = true; Set<String> mchNos = users.keySet(); WebSocketSession session = null; for (String mchNo : mchNos) { try { session = users.get(mchNo); if (session.isOpen()) { session.sendMessage(message); }else { logger.info("客戶端:{},已斷開連線,傳送訊息失敗", mchNo); } } catch (IOException e) { logger.info("sendMessageToAllUsers method error:{}", e); allSendSuccess = false; } } return allSendSuccess; } /** * 獲取使用者標識 * @Title: getMchNo * @Description: TODO * @Date 2018年8月21日 上午11:01:01 * @author OnlyMate * @param session * @return */ private String getMchNo(WebSocketSession session) { try { String mchNo = session.getAttributes().get(CLIENT_ID).toString(); return mchNo; } catch (Exception e) { return null; } } }
這個類的作用就是在連線成功前和成功後增加一些額外的功能
我們希望能夠把websocketSession和httpsession對應起來,這樣就能根據當前不同的session,定向對websocketSession進行資料返回;在查詢資料之後,發現spring中有一個攔截器介面,HandshakeInterceptor,可以實現這個介面,來攔截握手過程,向其中新增屬性
/** * WebSocket握手時的攔截器 * @ClassName: CustomWebSocketInterceptor * @Description: TODO * @author OnlyMate * @Date 2018年8月16日 下午3:17:04 * */ public class CustomWebSocketInterceptor implements HandshakeInterceptor { private Logger logger = LoggerFactory.getLogger(CustomWebSocketInterceptor.class); /** * 關聯HeepSession和WebSocketSession, * beforeHandShake方法中的Map引數 就是對應websocketSession裡的屬性 */ @Override public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler handler, Map<String, Object> map) throws Exception { if (request instanceof ServletServerHttpRequest) { logger.info("*****beforeHandshake******"); HttpServletRequest httpServletRequest = ((ServletServerHttpRequest) request).getServletRequest(); HttpSession session = httpServletRequest.getSession(true); logger.info("mchNo:{}", httpServletRequest.getParameter("mchNo")); if (session != null) { map.put("sessionId",session.getId()); map.put("mchNo", httpServletRequest.getParameter("mchNo")); } } return true; } @Override public void afterHandshake(ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse, WebSocketHandler webSocketHandler, Exception e) { logger.info("******afterHandshake******"); } }
這個類是配置類向Spring中注入handler
/** * websocket的配置類 * @ClassName: CustomWebSocketConfig * @Description: TODO * @author OnlyMate * @Date 2018年8月16日 下午3:17:26 * */ @Configuration @EnableWebSocket public class CustomWebSocketConfig implements WebSocketConfigurer { @Override public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) { registry.addHandler(customWebSocketHandler(), "/webSocketBySpring/customWebSocketHandler").addInterceptors(new CustomWebSocketInterceptor()).setAllowedOrigins("*"); registry.addHandler(customWebSocketHandler(), "/sockjs/webSocketBySpring/customWebSocketHandler").addInterceptors(new CustomWebSocketInterceptor()).setAllowedOrigins("*").withSockJS(); } @Bean public WebSocketHandler customWebSocketHandler() { return new CustomWebSocketHandler(); } }
補充說明:
setAllowedOrigins("*")一定要加上,不然只有訪問localhost,其他的不予許訪問
setAllowedOrigins(String[] domains),允許指定的域名或IP(含埠號)建立長連線,如果只允許自家域名訪問,這裡輕鬆設定。如果不限時使用"*"號,如果指定了域名,則必須要以http或https開頭
經查閱官方文件springwebsocket 4.1.5版本前預設支援跨域訪問,之後的版本預設不支援跨域,需要設定
使用withSockJS()的原因:
一些瀏覽器中缺少對WebSocket的支援,因此,回退選項是必要的,而Spring框架提供了基於SockJS協議的透明的回退選項。
SockJS的一大好處在於提供了瀏覽器相容性。優先使用原生WebSocket,如果在不支援websocket的瀏覽器中,會自動降為輪詢的方式。
除此之外,spring也對socketJS提供了支援。如果程式碼中添加了withSockJS()如下,伺服器也會自動降級為輪詢。
registry.addEndpoint("/coordination").withSockJS();
SockJS的目標是讓應用程式使用WebSocket API,但在執行時需要在必要時返回到非WebSocket替代,即無需更改應用程式程式碼。
SockJS是為在瀏覽器中使用而設計的。它使用各種各樣的技術支援廣泛的瀏覽器版本。對於SockJS傳輸型別和瀏覽器的完整列表,可以看到SockJS客戶端頁面。
傳輸分為3類:WebSocket、HTTP流和HTTP長輪詢(按優秀選擇的順序分為3類)客戶端
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt"%> <c:set var="ctx" value="${pageContext.request.contextPath}" /> <c:set var="ctxpath" value="${pageContext.request.scheme}${'://'}${pageContext.request.serverName}${':'}${pageContext.request.serverPort}${pageContext.request.contextPath}" /> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta charset=UTF-8"> <title>登入測試</title> </head> <body> <h2>Hello World! Web Socket by Spring</h2> <div> <span>sessionId:</span> <% HttpSession s= request.getSession(); out.println(s.getId()); %> </div> <input id="sessionId" type="hidden" value="<%=session.getId() %>" /> <input id="text" type="text" /> <button onclick="send()">傳送訊息</button> <hr /> <button onclick="closeWebSocket()">關閉WebSocket連線</button> <hr /> <div id="message"></div> </body> <script type="text/javascript" src="http://localhost:8088/static/js/sockjs-0.3.min.js"></script> <script type="text/javascript"> var websocket = null; //判斷當前瀏覽器是否支援WebSocket //判斷當前瀏覽器是否支援WebSocket if('WebSocket' in window) { websocket = new WebSocket("ws://localhost:8088/websocket/webSocketBySpring/customWebSocketHandler?mchNo="+ 123); } else if('MozWebSocket' in window) { websocket = new MozWebSocket("ws://localhost:8088/websocket/webSocketBySpring/customWebSocketHandler?mchNo="+ 123); } else { websocket = new SockJS("http://localhost:8088/websocket/sockjs/webSocketBySpring/customWebSocketHandler?mchNo="+ 123); } //連線發生錯誤的回撥方法 websocket.onerror = function () { setMessageInnerHTML("WebSocket連線發生錯誤"); }; //連線成功建立的回撥方法 websocket.onopen = function () { setMessageInnerHTML("WebSocket連線成功"); } //接收到訊息的回撥方法 websocket.onmessage = function (event) { setMessageInnerHTML(event.data); } //連線關閉的回撥方法 websocket.onclose = function () { setMessageInnerHTML("WebSocket連線關閉"); } //監聽視窗關閉事件,當視窗關閉時,主動去關閉websocket連線,防止連線還沒斷開就關閉視窗,server端會拋異常。 window.onbeforeunload = function () { closeWebSocket(); } //將訊息顯示在網頁上 function setMessageInnerHTML(innerHTML) { document.getElementById('message').innerHTML += innerHTML + '<br/>'; } //關閉WebSocket連線 function closeWebSocket() { websocket.close(); } //傳送訊息 function send() { var message = document.getElementById('text').value; websocket.send(message); } </script> </html>
效果如圖所示
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原文來自:https://blog.csdn.net/weixin_50770886/article/details/117569005