Spring Boot + WebSocket 实现实时消息推送
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
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