基于springboot实现最简单的websocket服务端实例

　　这里仅仅是为了模拟一个websocket服务端用于测试客户端的断连重连，重点是websocket的连接，所以内容就比较随意了，仅仅返回一个累加的整数。

　　1、引入spring boot的websocket包（版本号随spring boot自动引入，实际上这里是5.2.5）：

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>

　　2、最简化的配置类，一个端点，一个启动bean：

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocketMessageBroker;
import org.springframework.web.socket.config.annotation.StompEndpointRegistry;
import org.springframework.web.socket.config.annotation.WebSocketMessageBrokerConfigurer;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

/**
 * WebSocketMessageBrokerConfigurer 用来处理STOMP协议
 */
@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {


    /**
     * 添加一个服务端点，来接收客户端的连接
     * @param registry
     */
    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/ist").setAllowedOrigins("*");
    }

    /**
     * 开启WebSocket支持
     * @return
     */
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }

}

　　3、一个简单的websocket服务端：

/**
 * websocket服务端
 */
import com.alibaba.fastjson.JSON;
import org.springframework.web.bind.annotation.RestController;

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;

@ServerEndpoint("/ist")
@RestController
public class RtasrWS {
    private static final AtomicInteger segId = new AtomicInteger(1);

    @OnOpen
    public void onOpen(Session session) {
        System.out.println("I'm open.");

        // 获取请求url
        String url = session.getRequestURI().toString();
        System.out.println("request url: " + url);

        // 获取参数
        if (session.getRequestParameterMap().get("appId") != null) {
            System.out.println("appId: " + session.getRequestParameterMap().get("appId").get(0));
        }
    }

    private Object getResult() {
        Map<String, Object> result = new HashMap<>();
        result.put("seg_id", segId.getAndIncrement());
        return result;
    }

    @OnClose
    public void onClose() {
        System.out.println("I'm close.");
    }

    @OnMessage
    public void onMessage(String message, Session session) {
        System.out.println("I'm String onMessage.");
        sendMessage(session, JSON.toJSONString(getResult()));
    }

    @OnMessage
    public void onMessage(byte[] message, Session session) {
        System.out.println("I'm byte onMessage.");
        sendMessage(session, JSON.toJSONString(getResult()));
    }

    @OnError
    public void onError(Session session, Throwable error) {
        System.out.println("I'm error: " + error.getMessage());
    }

    private static void sendMessage(Session session, String message) {
        if (session == null)
            return;
        System.out.println("send msg : " + message);
        if (session.isOpen() && message.length() != 0) {
            try {
                session.getBasicRemote().sendText(message);
            } catch (Exception e) {
                System.out.println("send message error : " + e.getMessage());
                e.printStackTrace();
            }
        }
    }
}

　　就这样了，跑下spring boot，测试一下吧，我们用网页版的websocket客户端来测试，百度一下，最前面的是http://www.websocket-test.com，就它了：

 　　

　　日志：

2020-06-23 15:48:00 [http-nio-8089-exec-1] INFO  org.springframework.web.servlet.DispatcherServlet - Completed initialization in 0 ms 
I'm open.
request url: ws://127.0.0.1:8089/ist
I'm String onMessage.
send msg : {"seg_id":1}
I'm String onMessage.
send msg : {"seg_id":2}
I'm String onMessage.
send msg : {"seg_id":3}
I'm String onMessage.
send msg : {"seg_id":4}
2020-06-23 15:48:41 [MessageBroker-1] INFO  o.s.web.socket.config.WebSocketMessageBrokerStats - WebSocketSession[0 current WS(0)-HttpStream(0)-HttpPoll(0), 0 total, 0 closed abnormally (0 connect failure, 0 send limit, 0 transport error)], stompSubProtocol[processed CONNECT(0)-CONNECTED(0)-DISCONNECT(0)], stompBrokerRelay[null], inboundChannel[pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0], outboundChannel[pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 0], sockJsScheduler[pool size = 1, active threads = 1, queued tasks = 0, completed tasks = 0]