Spring Boot + WebSocket 实时消息推送

2020-05-10 本文已影响0人 AC编程

一、任务要求

商家的后台管理系统实现新订单提醒推送功能，利用Spring Boot + WebSocket实时消息推送的方式进行实现。

二、实现代码

2.1 前端html代码

<!DOCTYPE html>
<html>
    <head>
        <meta charset="UTF-8">
        <title>WebSocket</title>
    </head>
    <body>
        <input id="url" type="text" size="60" value="ws://localhost:8080/web_socket/order_notification/M666666" />
        <button onclick="openWebSocket()">打开WebSocket连接</button>


        <button onclick="closeWebSocket()">关闭WebSocket连接</button>
    
        <div id="message"></div>
    </body>
    <script type="text/javascript">
     　 var websocket = null;
 　　function openWebSocket() {
      var url = document.getElementById('url').value.trim();
      //判断当前浏览器是否支持WebSocket
            if ('WebSocket' in window) {
            websocket = new WebSocket(url);
      } else {
            alert('当前浏览器 Not support websocket')
      }
      //连接发生错误的回调方法
            websocket.onerror = function() {
            setMessageInnerHTML("WebSocket连接发生错误");
      };
      //连接成功建立的回调方法
            websocket.onopen = function() {
            setMessageInnerHTML("WebSocket连接成功");
      }
      //接收到消息的回调方法
            websocket.onmessage = function(event) {
            setMessageInnerHTML(event.data);
      }
      //连接关闭的回调方法
            websocket.onclose = function() {
            setMessageInnerHTML("WebSocket连接关闭");
      }
    }
    //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
        window.onbeforeunload = function() {
        closeWebSocket();
    }
    //将消息显示在网页上
        function setMessageInnerHTML(innerHTML) {
        document.getElementById('message').innerHTML += innerHTML + '<br/>';
    }
    //关闭WebSocket连接
        function closeWebSocket() {
        websocket.close();
    }
  </script>
</html>

2.2 服务端代码

引入依赖，我使用的是SpringBoot版本2.2.6.RELEASE，自动管理依赖版本

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

配置类WebSocketConfig，扫描并注册带有@ServerEndpoint注解的所有websocket服务端

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

/**
 * @author Alan Chen
 * @description 开启WebSocket支持
 * @date 2020-04-08
 */
@Configuration
public class WebSocketConfig {
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }
}

新建WebSocketServer类，WebSocket服务端是多例的，一次WebSocket连接对应一个实例

import org.springframework.stereotype.Component;
import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @author Alan Chen
 * @description 订单通知
 * @date 2020-04-08
 */
@Component
@ServerEndpoint("/web_socket/order_notification/{merchantId}")
public class OrderNotificationWebSocket {

    static final ConcurrentHashMap<String, List<WebSocketClient>> webSocketClientMap= new ConcurrentHashMap<>();

    /**
     * 连接建立成功时触发，绑定参数
     * @param session 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
     * @param merchantId 商户ID
     */
    @OnOpen
    public void onOpen(Session session,@PathParam("merchantId") String merchantId){

        WebSocketClient client = new WebSocketClient();
        client.setSession(session);
        client.setUri(session.getRequestURI().toString());

        List<WebSocketClient> webSocketClientList = webSocketClientMap.get(merchantId);
        if(webSocketClientList == null){
            webSocketClientList = new ArrayList<>();
        }
        webSocketClientList.add(client);
        webSocketClientMap.put(merchantId, webSocketClientList);
    }

    /**
     * 连接关闭时触发，注意不能向客户端发送消息了
     * @param merchantId
     */
    @OnClose
    public void onClose(@PathParam("merchantId") String merchantId){
        webSocketClientMap.remove(merchantId);
    }

    /**
     * 通信发生错误时触发
     * @param session
     * @param error
     */
    @OnError
    public void onError(Session session, Throwable error) {
        System.out.println("发生错误");
        error.printStackTrace();
    }

    /**
     * 向客户端发送消息
     * @param merchantId
     * @param message
     */
    public static void sendMessage(String merchantId,String message){
        try {
            List<WebSocketClient> webSocketClientList = webSocketClientMap.get(merchantId);
            if(webSocketClientList!=null){
                for(WebSocketClient webSocketServer:webSocketClientList){
                    webSocketServer.getSession().getBasicRemote().sendText(message);
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
            throw new RuntimeException(e.getMessage());
        }
    }

}

辅助类

import lombok.Data;

import javax.websocket.Session;

/**
 * @author Alan Chen
 * @description WebSocket客户端连接
 * @date 2020-04-08
 */
@Data
public class WebSocketClient {

    // 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;

    //连接的uri
    private String uri;

}

新建一个测试类，用于向客户端发送推送消息

import com.yh.supermarket.manage.websocket.OrderNotificationWebSocket;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;


/**
 * @author Alan Chen
 * @description
 * @date 2020-04-08
 */
@Api(tags = "WebSocket-test")
@RestController("notification")
public class OrderNotificationWebSocketController {

    @ApiOperation("通知test")
    @GetMapping
    public void test(@RequestParam String merchantId){
        OrderNotificationWebSocket.sendMessage(merchantId,"有新订单啦");
    }
}