一起学习Spring Boot 2.X | 第十九篇：WebSocket

1.POM

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

2.配置WebSocketConfig

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

/**
 * 开启WebSocket支持
 * @author zhengkai
 */
@Configuration
public class WebSocketConfig {

    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }

}

3.MyWebSocket

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import org.springframework.ui.ModelMap;
import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;

@ServerEndpoint(value = "/websocket")
@Component
public class MyWebSocket {

    private final static Logger logger = LoggerFactory.getLogger(MyWebSocket.class);

    //静态变量，用来记录当前在线连接数。应该把它设计成线程安全的。
    private static 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<MyWebSocket> webSocketSet = new CopyOnWriteArraySet<MyWebSocket>();

    //与某个客户端的连接会话，需要通过它来给客户端发送数据
    private Session session;

    /**
     * 连接建立成功调用的方法
     */
    @OnOpen
    public void onOpen(Session session) {
        try {
            this.session = session;
            System.out.println(this.session.getRequestURI().getHost());
            webSocketSet.add(this);//加入set中
            addOnlineCount();//在线数加1
            System.out.println("当前在线人数为" + getOnlineCount());
            sendMessage("连接成功");
        } catch (Exception e) {
            System.out.println(("WebSocket异常"));
        }
    }

    /**
     * 连接关闭调用的方法
     */
    @OnClose
    public void onClose() throws IOException {
        webSocketSet.remove(this);//从set中删除
        subOnlineCount();//在线数减1
        System.out.println(("连接关闭！当前在线人数为" + getOnlineCount()));
    }

    /**
     * 收到客户端消息后调用的方法
     *
     * @param message 客户端发送过来的消息
     */
    @OnMessage
    public void onMessage(Session session, String message) {
        System.out.println("来自客户端的消息:" + message);
    }

    /**
     * 发生错误时调用
     */
    @OnError
    public void onError(Session session, Throwable error) {
        System.out.println("发生错误");
        error.printStackTrace();
    }

    /**
     * 实现服务器主动推送
     */
    public void sendMessage(String message) throws IOException {
        ModelMap modelMap = new ModelMap();
        modelMap.put("A","a");
        modelMap.put("B","b");
        this.session.getBasicRemote().sendText(modelMap.toString());

    }

    /**
     * 群发自定义消息
     * */
    public static void sendInfo(String message,@PathParam("sid") String sid) throws IOException {
        for (MyWebSocket item : webSocketSet) {
            System.out.println(item);
            try {
                //这里可以设定只推送给这个sid的，为null则全部推送
                if(sid==null) {
                    item.sendMessage(message);
                }
            } catch (IOException e) {
                continue;
            }
        }
    }


    public static synchronized int getOnlineCount() {
        return onlineCount;
    }


    public static synchronized void addOnlineCount() {
        MyWebSocket.onlineCount++;
    }

    public static synchronized void subOnlineCount() {
        MyWebSocket.onlineCount--;
    }

}

4.如需推送信息

import com.demo.utils.MyWebSocket;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.io.IOException;

@RestController
public class TestControllwe {

    @RequestMapping("/")
    public String Text(){
        try {
            MyWebSocket.sendInfo("Test",null);
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

5.打包

POM添加依赖打包

<!-- WebSocket打包 -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <configuration>
                    <skip>true</skip>
                </configuration>
            </plugin>