spring-boot实现websocket

服务端

服务端的实现，通常有两种方式：

一种用@ServerEndPoint注解来实现；第二种通过请求参数传递采方式，服务端的参数在拦截器中获取之后通过attributes传递给WebSocketHandler，可以添加拦截器在WebSocket连接建立和断开前进行一些其他操作。

其实第一种也就是前面说过的java封装的一种实现。因为在spring-boot中，需要把类注册到容器，还需要配置：

//自动注册所有@ServerEndpoint注解声明的WebsocketEndpoint
@Configuration
public class WebSocketConfig {
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }
    
}

@ServerEndpoint实现的时候，可能会出现注入失败的问题，可以通过手动注入的方式来解决。

ConfigurableApplicationContext applicationContext = new SpringApplication(Application.class).run(args);
WebSocketController.setApplicationContext(applicationContext);  // 再在WebSocketController中获取Bean

第二种实现就是和spring差不多，实现WebSocketHandler，或者更有可能扩展TextWebSocketHandler或BinaryWebSocketHandler。

示例：

pom：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <artifactId>SpringBoot-websocket</artifactId>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-parent</artifactId>
        <version>2.1.8.RELEASE</version>
    </parent>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-websocket</artifactId>
    </dependency>
    <dependency>
        <groupId>org.java-websocket</groupId>
        <artifactId>Java-WebSocket</artifactId>
        <version>1.3.5</version>
    </dependency>
</dependencies>
</project>

java：

//配置类
@Configuration
@EnableWebMvc
@EnableWebSocket
public class WebSocketConfig implements WebMvcConfigurer,WebSocketConfigurer {

    @Autowired
    private WebSocketController webSocketController;

    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(webSocketController, "/webSocket")
                .addInterceptors(new HandShakeInterceptor()).setAllowedOrigins("*");
    }

}
//拦截器
public class HandShakeInterceptor extends HttpSessionHandshakeInterceptor {
    private final Logger logger = LoggerFactory.getLogger(HandShakeInterceptor.class);

    /*
     * 在WebSocket连接建立之前的操作，以鉴权为例
     */
    public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response,
                                   WebSocketHandler wsHandler, Map<String, Object> attributes) throws Exception {
        //一些鉴权操作
        return true;
    }

    public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response,
                               WebSocketHandler wsHandler, Exception ex) {

    }

}
//控制器
@RestController
public class WebSocketController implements WebSocketHandler {

    private static AtomicInteger onlineCount = new AtomicInteger(0);

    private static final ArrayList<WebSocketSession> sessions = new ArrayList<>();

    private final Logger LOGGER = LoggerFactory.getLogger(WebSocketController.class);

    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        sessions.add(session);
        int onlineNum = onlineCount.incrementAndGet();
        LOGGER.info("打开连接，目前连接数: " + onlineNum);
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
        sessions.remove(session);
        int onlineNum = onlineCount.decrementAndGet();
        LOGGER.info("连接关闭: " + onlineNum);
    }

    @Override
    public void handleMessage(WebSocketSession wsSession, WebSocketMessage<?> message) throws Exception {
        LOGGER.info("收到的消息: " + message.toString());
    }

    @Override
    public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
        LOGGER.error("连接错误");
        if (session.isOpen()) {
            session.close();
        }
        sessions.remove(session);
        onlineCount.decrementAndGet();
    }

    /*
     * 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，可能这里由问题。
     */
    @Override
    public boolean supportsPartialMessages() {
        return true;
    }
}

//
@SpringBootApplication
@ComponentScan("com.hu.demo")
public class App {
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}

启动

客户端

客户端的实现，通常有html和java WebSocketClient两种方式，html前面已经有，这里用client实现一下：

public class WebSocketClientDemo extends WebSocketClient {

    public WebSocketClientDemo(String url) throws URISyntaxException {
        super(new URI(url));
    }
    public WebSocketClientDemo(URI serverUri, Draft protocolDraft) {
        super(serverUri, protocolDraft);
    }

    @Override
    public void onOpen(ServerHandshake shake) {
        System.out.println("握手...");
        for (Iterator<String> it = shake.iterateHttpFields(); it.hasNext(); ) {
            String key = it.next();
            System.out.println(key + ":" + shake.getFieldValue(key));
        }
    }

    @Override
    public void onMessage(String paramString) {
        System.out.println("接收到消息：" + paramString);
    }

    @Override
    public void onClose(int paramInt, String paramString, boolean paramBoolean) {
        System.out.println("关闭...");
    }

    @Override
    public void onError(Exception e) {
        System.out.println("异常" + e);

    }

}

测试：

public class ClientDemo {
    public static void main(String[] args) throws Exception{
        String serverUrl = "ws://127.0.0.1:8080/webSocket";
        URI recognizeUri = new URI(serverUrl);
        WebSocketClientDemo client = new WebSocketClientDemo(recognizeUri, new Draft_6455());
        client.connect();
        while (!client.getReadyState().equals(WebSocket.READYSTATE.OPEN)) {
            System.out.println("未打开");
        }
        System.out.println("建立websocket连接");
        client.send("hello");
    }
}

结果：

未打开
未打开
未打开
未打开
未打开
未打开
握手...
已经连接
Connection:upgrade
Date:Sat, 04 Apr 2020 09:26:08 GMT
Sec-WebSocket-Accept:SIBN8X8GwCVQmjNH1VNNZnr+WY4=
Upgrade:websocket