文章目录

• 1.添加依赖
• 2.编辑WebSocketConfig，
• 3.编写WebSocketHandlerInterceptor
• 4.编写MyWebSocketHandler
• • 使用
• 5.自定义解码器
• • 使用

1.添加依赖

org.springframeworkspring-messaging4.1.7.RELEASE

org.springframeworkspring-websocket4.1.7.RELEASE

javax.websocketjavax.websocket-api1.0provided

2.编辑WebSocketConfig，

根据spring文档，编写websocketConfig，这里可参看文档，xml配置和使用注解两种方式，我选择注解方式

registerWebSocketHandlers：这个方法是向spring容器注册一个handler地址，我把他理解成requestMapping（也可以理解为@ServerEndpoint(“/webSocket”)）

addInterceptors：拦截器，当建立websocket连接的时候，我们可以通过继承spring的HttpSessionHandshakeInterceptor来搞事情。

setAllowedOrigins：跨域设置，表示所有域名都可以，不限制， 域包括ip：port, 指定可以是任意的域名，不加的话默认localhost+本服务端口

withSockJS： 这个是应对浏览器不支持websocket协议的时候降级为轮询的处理。

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {@Overridepublic void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {registry.addHandler(webSocketHandler(), "/websocket/socketServer").addInterceptors(new WebSocketHandlerInterceptor()).setAllowedOrigins("*");registry.addHandler(webSocketHandler(), "/sockjs/socketServer").setAllowedOrigins("http://localhost:28180").addInterceptors(new WebSocketHandlerInterceptor()).withSockJS();}@Beanpublic TextWebSocketHandler webSocketHandler() {return new WebSocketHandler();}
}

3.编写WebSocketHandlerInterceptor

这个是创建websocket连接是的拦截器，记录建立连接的用户的session以便根据不同session来通信

public class WebSocketHandlerInterceptor extends HttpSessionHandshakeInterceptor {@Overridepublic boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler,Map attributes) throws Exception {System.out.println("Before Handshake");if (request instanceof ServletServerHttpRequest) {ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) request;HttpSession session = servletRequest.getServletRequest().getSession(false);if (session != null) {//使用userName区分WebSocketHandler，以便定向发送消息String userName = (String) session.getAttribute("SESSION_USERNAME");  //一般直接保存user实体if (userName != null) {attributes.put("WEBSOCKET_USERID", userName);}}}return super.beforeHandshake(request, response, wsHandler, attributes);}@Overridepublic void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler,Exception ex) {super.afterHandshake(request, response, wsHandler, ex);}}

4.编写MyWebSocketHandler

@Configuration
public class MyWebSocketHandler extends TextWebSocketHandler {//Map来存储WebSocketSession，key用USER_ID 即在线用户列表private static ConcurrentHashMap users = new ConcurrentHashMap<>();//用户标识private static final String USER_ID = "WEBSOCKET_USERID";   //对应监听器从的keypublic MYWebSocketHandler() {}/*** 连接成功时候，会触发页面上onopen方法*/@Overridepublic void afterConnectionEstablished(WebSocketSession session) throws Exception {System.out.println("成功建立websocket连接!");String userId = session.getId();users.put(userId, session);System.out.println("当前线上用户数量:" + users.size());//这块会实现自己业务，比如，当用户登录后，会把离线消息推送给用户//TextMessage returnMessage = new TextMessage("成功建立socket连接，你将收到的离线");//session.sendMessage(returnMessage);}/*** 关闭连接时触发*/@Overridepublic void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {String userId = (String) session.getAttributes().get(USER_ID);System.out.println("用户" + userId + "已退出！");users.remove(userId);System.out.println("剩余在线用户" + users.size());}/*** js调用websocket.send时候，会调用该方法*/@Overrideprotected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {/*** 收到消息，自定义处理机制，实现业务*/System.out.println("服务器收到消息：" + message);if (message.getPayload().startsWith("#anyone#")) { //单发某人sendMessageToUser((String) session.getAttributes().get(USER_ID), new TextMessage("服务器单发：" + message.getPayload()));} else if (message.getPayload().startsWith("#everyone#")) {sendMessageToUsers(new TextMessage("服务器群发：" + message.getPayload()));} else {}}@Overridepublic void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {if (session.isOpen()) {session.close();}System.out.println("传输出现异常，关闭websocket连接... ");String userId = (String) session.getAttributes().get(USER_ID);users.remove(userId);}@Overridepublic boolean supportsPartialMessages() {return false;}/*** 给某个用户发送消息** @param userId* @param message*/public void sendMessageToUser(String userId, TextMessage message) {for (String id : users.keySet()) {if (id.equals(userId)) {try {if (users.get(id).isOpen()) {users.get(id).sendMessage(message);}} catch (IOException e) {e.printStackTrace();}break;}}}/*** 给所有在线用户发送消息** @param message*/public void sendMessageToUsers(TextMessage message) {for (String userId : users.keySet()) {try {if (users.get(userId).isOpen()) {users.get(userId).sendMessage(message);}} catch (IOException e) {e.printStackTrace();}}}
}

使用

@Autowired
MyWebSocketHandler webSocket;

5.自定义解码器

public class WebSocketCustomEncoding implements Encoder.Text

使用

@ServerEndpoint(value = "/webSocketService", encoders = {ImageEncoder.class})