Springboot websocket简单使用

1、在pom.xml导入依赖

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

2、在Spring Boot项目的service层中创建一个Host类，其中包含一个getCPUUsage()方法用于定时获取远程CentOS 7系统的CPU使用率。你可以使用JSch库来连接远程服务器，并执行相应的命令来获取CPU使用率。

import org.springframework.scheduling.annotation.Scheduled;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import com.jcraft.jsch.ChannelExec;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.JSchException;
import com.jcraft.jsch.Session;

public class Host {
    private Set<WebSocketSession> sessions = new HashSet<>();

    public void addSession(WebSocketSession session) {
        sessions.add(session);
    }

    public void removeSession(WebSocketSession session) {
        sessions.remove(session);
    }

    public void sendCPUUsageToAllSessions(double cpuUsage) throws IOException {
        for (WebSocketSession session : sessions) {
            session.sendMessage(new TextMessage(String.valueOf(cpuUsage)));
        }
    }

    @Scheduled(fixedRate = 1000) // 每秒执行一次
    public void getCPUUsage() throws JSchException, IOException {
        JSch jSch = new JSch();
        Session session = jSch.getSession("username", "hostname", 22);
        session.setPassword("password");
        session.setConfig("StrictHostKeyChecking", "no");
        session.connect();

        ChannelExec channel = (ChannelExec) session.openChannel("exec");
        channel.setCommand("top -bn 1 | grep \"Cpu(s)\" | awk '{print $2 + $4}'");
        channel.connect();

        BufferedReader reader = new BufferedReader(new InputStreamReader(channel.getInputStream()));
        String cpuUsageString = reader.readLine();
        double cpuUsage = Double.parseDouble(cpuUsageString);
        reader.close();

        channel.disconnect();
        session.disconnect();

        sendCPUUsageToAllSessions(cpuUsage);
    }
}

3、在Spring Boot项目中配置WebSocket，创建一个WebSocketHandler用于处理WebSocket连接、消息和关闭操作。

import org.springframework.stereotype.Component;
import org.springframework.web.socket.*;
import org.springframework.web.socket.handler.TextWebSocketHandler;

@Component
public class MyWebSocketHandler extends TextWebSocketHandler {
    private final Host host;

    public MyWebSocketHandler(Host host) {
        this.host = host;
    }

    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        host.addSession(session);
    }

    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        // 处理接收到的消息，如果需要的话
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
        host.removeSession(session);
    }
}

4、在Spring Boot的配置类中配置WebSocket相关的Bean和路径映射。

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
    private final MyWebSocketHandler myWebSocketHandler;

    @Autowired
    public WebSocketConfig(MyWebSocketHandler myWebSocketHandler) {
        this.myWebSocketHandler = myWebSocketHandler;
    }

    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(myWebSocketHandler, "/ws").setAllowedOrigins("*");
    }
}

5、在Spring Boot的启动类上加上@EnableScheduling

6、在你的Vue.js项目中，创建WebSocket连接并处理收到的消息。

socket.onmessage = (event) => {
        this.tableData = JSON.parse(event.data).data;
        // 处理接收到的CPU使用率数据
        console.log(this.tableData);
      };

通过以上步骤，你可以实现在Spring Boot的service层通过JSch定时获取远程CentOS 7系统的CPU使用率，并使用WebSocket主动发送给连接的Vue.js项目的页面。在Vue.js项目中，通过创建WebSocket连接并处理接收到的消息，即可实时接收并处理CPU使用率数据。请根据实际情况对代码进行适当修改和优化。记得在Spring Boot的启动类上加上@EnableScheduling注解启用定时任务。