WebSocket是实现消息推送

一、项目介绍

           用springboot实现服务端（后台）想前端发送消息通知

 

二、项目背景

          假设有一个用户前往医院找专家看病的场景，一个专家对应多个用户，当第一个用户看病结束后通知第二用户前往房间，

传统的模式都是服务端发起请求，服务端响应请求，返回数据给我客户端。考虑到 socket是一个全双工的协议，既可以是客户端也

可以是服务端，于是选择了WebSocket.

 

三、项目目录结构

 

           

 四、项目代码

 

           

---------------------------------项目环境依赖---------------------------------------
	
			org.springframework.boot
			spring-boot-starter-web
		
		
			org.springframework.boot
			spring-boot-starter-websocket
		

		
			org.projectlombok
			lombok
			true
		

----------------------Controller层-----------------------------------
package com.gpdi.controller;

import com.gpdi.config.WebSocket;
import com.gpdi.util.ResponseData;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.annotation.Resource;
import java.io.IOException;



/**
 * @desc: 用Socket实现服务端到客户端消息的单发和群发
 */
@Controller
public class SocketController {

    /**
     * @desc: 向所有人发送消息
     */
    @RequestMapping("sendToAll")
    @ResponseBody
    public ResponseData sendToAll() {

        webSocket.sendMessage("服务端向客户端消息群发！");
        return new ResponseData(200, "群发请求成功");

    }

    /**
     * @desc: 向某个人发送消息
     */
    @RequestMapping("sendToOne")
    @ResponseBody
    public ResponseData sendToOne(String sessionId) throws IOException {
        webSocket.sendMessage(sessionId, "向SessionId为" + sessionId + "的用户发送消息通知");
        return new ResponseData(200, "单发请求成功", sessionId);
    }

    @Resource
    WebSocket webSocket;

}

--------------------------------WebSocket配置文件---------------------------

package com.gpdi.config;
import lombok.extern.slf4j.Slf4j;
import org.springframework.context.annotation.Bean;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;
import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArraySet;
@Component
@ServerEndpoint(value = "/webSocket")
@Slf4j
public class WebSocket {
    //每个客户端都会有相应的session,服务端可以发送相关消息
    private Session session;

    private static CopyOnWriteArraySet copyOnWriteArraySet = new CopyOnWriteArraySet();
    //存储userId和SessionId
    private Map map = new ConcurrentHashMap<>();

    /**
     * 打开连接。进入页面后会自动发请求到此进行连接
     *
     * @param session
     */
    @OnOpen
    public void onOpen(Session session) {
        String sessionUrl = session.getRequestURI().toString();
        String username = sessionUrl.substring(sessionUrl.indexOf("="), sessionUrl.length()).substring(1);
        map.put(username, session.getId());
        System.out.println("以下是最新的遍历结果");
        map.keySet().forEach((a) -> {
            System.out.println("用户为" + a + "用户的SessionID为" + map.get(a));
        });
        this.session = session;
        copyOnWriteArraySet.add(this);
        log.info("websocket有新的连接, 总数:" + copyOnWriteArraySet.size());
    }

    /**
     * 用户关闭页面，即关闭连接
     */
    @OnClose
    public void onClose() {
        copyOnWriteArraySet.remove(this);
        log.info("webSocket连接断开, 总数:" + copyOnWriteArraySet.size());
    }

    /**
     * 测试客户端发送消息，测试是否联通
     *
     * @param message
     */
    @OnMessage
    public void onMessage(String message) {
        log.info("websocket收到客户端发来的消息:" + message);
    }


    /**
     * 出现错误
     *
     * @param session
     * @param error
     */
    @OnError
    public void onError(Session session, Throwable error) {
        log.error("发生错误：" + error.getMessage(), session.getId());
        error.printStackTrace();
    }

    /**
     * 用于发送给客户端消息（群发）
     *
     * @param message
     */

    public void sendMessage(String message) {
        //遍历客户端
        for (WebSocket webSocket : copyOnWriteArraySet) {
            log.info("websocket广播消息：" + message);
            try {
                //服务器主动推送
                webSocket.session.getBasicRemote().sendText(message);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 用于发送给指定客户端消息
     *
     * @param message
     */
    public void sendMessage(String sessionId, String message) throws IOException {
        //这里有一个Session,最外面还有一个全局Session
        Session session = null;
        WebSocket tempWebSocket = null;
        for (WebSocket webSocket : copyOnWriteArraySet) {
            if (webSocket.session.getId().equals(sessionId)) {
                tempWebSocket = webSocket;
                session = webSocket.session;
                break;
            }
        }
        if (session != null) {
            tempWebSocket.session.getBasicRemote().sendText(message);
        } else {
            log.warn("没有找到你指定ID的会话：{}", sessionId);
        }
    }

    /**
     * @return
     */
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {

        return new ServerEndpointExporter();
    }


}
----------------------------------工具包------------------------------------
package com.gpdi.util;
/**
 *
 * @desc:封装自定义返回数据工具类
 *
 */
public class ResponseData {
    private int state;
    private String msg;
    private Object object;

    public int getState() {
        return state;
    }

    public void setState(int state) {
        this.state = state;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public Object getObject() {
        return object;
    }

    public void setObject(Object object) {
        this.object = object;
    }

    public ResponseData(int state, String msg) {
        this.state = state;
        this.msg = msg;
    }

    public ResponseData() {
    }

    public ResponseData(int state, String msg, Object object) {
        this.state = state;
        this.msg = msg;
        this.object = object;
    }
}

----------------------------------启动文件-------------------

package com.gpdi;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {

	public static void main(String[] args) {
		SpringApplication.run(Application.class, args);
	}
}
------------------------------------- 系统页面---------------------------



    
    


当前页面为Socket客户端