SpringBoot跟WebSocket的开发过程是怎样的

SpringBoot跟WebSocket的开发过程是怎样的，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。

1. 服务端的实现，我尝试了两种方式：

• 第一种是用"@ServerEndPoint"注解来实现，实现简单；

• 第二种稍显麻烦，但是可以添加拦截器在WebSocket连接建立和断开前进行一些额外操作。

　　不管用哪种实现方式，都需要先导入jar包（如下），其中version根据实际springboot版本选择，避免冲突

    org.springframework.boot    spring-boot-starter-websocket    

1.1 第一种实现方法

（1）WebSocket 业务逻辑实现。参数传递采用路径参数的方法，通过以下方式获取参数：

• @ServerEndpoint("/testWebSocket/{id}/{name}")

• public void onOpen(Session session, @PathParam("id") long id, @PathParam("name") String name)

import java.util.concurrent.CopyOnWriteArraySet;import javax.websocket.OnClose;import javax.websocket.OnError;import javax.websocket.OnMessage;import javax.websocket.OnOpen;import javax.websocket.Session;import javax.websocket.server.ServerEndpoint;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.web.bind.annotation.RestController;@ServerEndpoint("/testWebSocket/{id}/{name}")@RestControllerpublic class TestWebSocket {    // 用来记录当前连接数的变量    private static volatile int onlineCount = 0;    // concurrent包的线程安全Set，用来存放每个客户端对应的MyWebSocket对象    private static CopyOnWriteArraySet webSocketSet = new CopyOnWriteArraySet();    // 与某个客户端的连接会话，需要通过它来与客户端进行数据收发    private Session session;    private static final Logger LOGGER = LoggerFactory.getLogger(TestWebSocket.class);    　　@OnOpen    public void onOpen(Session session, @PathParam("id") long id, @PathParam("name") String name) throws Exception {        this.session = session;        System.out.println(this.session.getId());        webSocketSet.add(this);        LOGGER.info("Open a websocket. id={}, name={}", id, name);    }    @OnClose    public void onClose() {        webSocketSet.remove(this);        LOGGER.info("Close a websocket. ");    }    @OnMessage    public void onMessage(String message, Session session) {        LOGGER.info("Receive a message from client: " + message);    }    @OnError    public void onError(Session session, Throwable error) {        LOGGER.error("Error while websocket. ", error);    }    public void sendMessage(String message) throws Exception {        if (this.session.isOpen()) {            this.session.getBasicRemote().sendText("Send a message from server. ");        }    }    public static synchronized int getOnlineCount() {        return onlineCount;    }    public static synchronized void addOnlineCount() {        TestWebSocket.onlineCount++;    }    public static synchronized void subOnlineCount() {        TestWebSocket.onlineCount--;    }}

（2）配置ServerEndpointExporter，配置后会自动注册所有"@ServerEndpoint"注解声明的Websocket Endpoint

import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.web.socket.server.standard.ServerEndpointExporter; @Configurationpublic class WebSocketConfig {     @Bean    public ServerEndpointExporter serverEndpointExporter() {        return new ServerEndpointExporter();    } }

1.2 第二种实现方法

（1）WebSocket 业务逻辑实现。参数传递采用类似GET请求的方式传递，服务端的参数在拦截器中获取之后通过attributes传递给WebSocketHandler。

import java.util.ArrayList;import java.util.concurrent.atomic.AtomicInteger; import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.web.bind.annotation.RestController;import org.springframework.web.socket.CloseStatus;import org.springframework.web.socket.WebSocketHandler;import org.springframework.web.socket.WebSocketMessage;import org.springframework.web.socket.WebSocketSession; @RestControllerpublic class TestWebSocketController implements WebSocketHandler {     private static AtomicInteger onlineCount = new AtomicInteger(0);     private static final ArrayList sessions = new ArrayList<>();     private final Logger LOGGER = LoggerFactory.getLogger(TestWebSocketController.class);     @Override    public void afterConnectionEstablished(WebSocketSession session) throws Exception {        sessions.add(session);        int onlineNum = addOnlineCount();        LOGGER.info("Oprn a WebSocket. Current connection number: " + onlineNum);    }     @Override    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {        sessions.remove(session);        int onlineNum = subOnlineCount();        LOGGER.info("Close a webSocket. Current connection number: " + onlineNum);    }     @Override    public void handleMessage(WebSocketSession wsSession, WebSocketMessage message) throws Exception {        LOGGER.info("Receive a message from client: " + message.toString());    }     @Override    public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {        LOGGER.error("Exception occurs on webSocket connection. disconnecting....");        if (session.isOpen()) {            session.close();        }        sessions.remove(session);        subOnlineCount();    }     /*     * 是否支持消息拆分发送：如果接收的数据量比较大，最好打开(true), 否则可能会导致接收失败。     * 如果出现WebSocket连接接收一次数据后就自动断开，应检查是否是这里的问题。     */    @Override    public boolean supportsPartialMessages() {        return true;    }     public static int getOnlineCount() {        return onlineCount.get();    }     public static int addOnlineCount() {        return onlineCount.incrementAndGet();    }     public static int subOnlineCount() {        return onlineCount.decrementAndGet();    } }

（2）HandShake 拦截器实现

import java.util.Map; import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.ApplicationContext;import org.springframework.http.server.ServerHttpRequest;import org.springframework.http.server.ServerHttpResponse;import org.springframework.http.server.ServletServerHttpRequest;import org.springframework.web.socket.WebSocketHandler;import org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor; public class TestHandShakeInterceptor extends HttpSessionHandshakeInterceptor {     private final Logger LOGGER = LoggerFactory.getLogger(TestHandShakeInterceptor.class);     /*     * 在WebSocket连接建立之前的操作，以鉴权为例     */    @Override    public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response,            WebSocketHandler wsHandler, Map attributes) throws Exception {         LOGGER.info("Handle before webSocket connected. ");         // 获取url传递的参数，通过attributes在Interceptor处理结束后传递给WebSocketHandler        // WebSocketHandler可以通过WebSocketSession的getAttributes()方法获取参数        ServletServerHttpRequest serverRequest = (ServletServerHttpRequest) request;        String id = serverRequest.getServletRequest().getParameter("id");        String name = serverRequest.getServletRequest().getParameter("name");         if (tokenValidation.validateSign()) {            LOGGER.info("Validation passed. WebSocket connecting.... ");            attributes.put("id", id);            attributes.put("name", name);            return super.beforeHandshake(request, response, wsHandler, attributes);        } else {            LOGGER.error("Validation failed. WebSocket will not connect. ");            return false;        }    }     @Override    public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response,            WebSocketHandler wsHandler, Exception ex) {        // 省略    } }

（3）WebSocket 配置类实现（注册WebSocket实现类，绑定接口，同时将实现类和拦截器绑定）

import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.EnableWebMvc;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;import org.springframework.web.socket.config.annotation.EnableWebSocket;import org.springframework.web.socket.config.annotation.WebSocketConfigurer;import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry; import TestWebSocketController;import TestHandShakeInterceptor; @Configuration@EnableWebMvc@EnableWebSocketpublic class WebSocketConfig extends WebMvcConfigurerAdapter implements WebSocketConfigurer {     @Autowired    private TestWebSocketController testWebSocketController;     @Override    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {        registry.addHandler(TestWebSocketController, "/testWebSocket")                .addInterceptors(new TestHandShakeInterceptor()).setAllowedOrigins("*");    } }

1.3 补充说明

（1）在WebSocket实现过程中，尤其是通过"@ServerEndpoint"实现的时候，可能会出现注入失败的问题，即注入的Bean为null的问题。可以通过手动注入的方式来解决，需要改造实现类和SpringBoot启动类，如下：

@ServerEndpoint("testWebsocket")@RestControllerpublic class WebSocketController {     private TestService testService;     private static ApplicationContext applicationContext;     @OnOpen    public void onOpen(Session session) {        testService = applicationContext.getBean(TestService.class);    }     @OnClose    public void onClose() {}     @OnMessage    public void onMessage(String message, Session session) {}     @OnError    public void onError(Session session, Throwable error) {}     public static void setApplicationContext(ApplicationContext applicationContext) {        WebSocketController.applicationContext = applicationContext;    } }

import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.context.ConfigurableApplicationContext; import WebSocketController; @SpringBootApplicationpublic class Application {     public static void main(String[] args) {//        SpringApplication.run(Application.class, args);        SpringApplication springApplication = new SpringApplication(Application.class);        ConfigurableApplicationContext configurableApplicationContext = springApplication.run(args);        WebSocketController.setApplicationContext(configurableApplicationContext);  // 解决WebSocket不能注入的问题    } }

2. 客户端的实现，我尝试了html和java WebSocketClient两种方式

2.1 html实现

                    发送消息    
    关闭WebSocket连接    
    
 

2.2 Java WebSocketClient实现

（1）WebSocketClient 实现类

import java.net.URI; import org.java_websocket.client.WebSocketClient;import org.java_websocket.drafts.Draft;import org.java_websocket.handshake.ServerHandshake;import org.slf4j.Logger;import org.slf4j.LoggerFactory; public class TestWebSocketClient extends WebSocketClient {     private final Logger LOGGER = LoggerFactory.getLogger(TestWebSocketClient.class);     public TestWebSocketClient(URI serverUri) {        super(serverUri);    }     public TestWebSocketClient(URI serverUri, Draft protocolDraft) {        super(serverUri, protocolDraft);    }     @Override    public void onOpen(ServerHandshake serverHandshake) {        LOGGER.info("Open a WebSocket connection on client. ");    }     @Override    public void onClose(int arg0, String arg1, boolean arg2) {        LOGGER.info("Close a WebSocket connection on client. ");    }     @Override    public void onMessage(String msg) {        LOGGER.info("WebSocketClient receives a message: " + msg);    }     @Override    public void onError(Exception exception) {        LOGGER.error("WebSocketClient exception. ", exception);    } }

（2）WebSocketClient 发送数据

String serverUrl = "ws://127.0.0.1:18080/testWebsocket"URI recognizeUri = new URI(serverUrl);client = new TestWebSocketClient(recognizeUri, new Draft_6455());client.connect();client.send("This is a message from client. ");

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