WebSocket是一种在单个TCP传输控制协议连接上进行全双工全双工通信的协议。WebSocket使得客户端和服务器之间的数据交换变得更加简单，允许服务端主动向客户端推送数据。在WebSocket API中，浏览器和服务器只需要完成一次握手，两者之间就直接可以创建持久性的连接，并进行双向数据传输。
Websocket的使用
- 添加依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-websocket</artifactId>
</dependency>
- Websocket配置类
@Configuration
public class WebSocketConfig {
@Bean
public ServerEndpointExporter serverEndpointExporter() {
return new ServerEndpointExporter();
}
}
- Websocket服务类
@ServerEndpoint("/websocket")
@Component
public class WebSocketServer {
//静态变量，用来记录当前在线连接数,可选
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，必须
private static CopyOnWriteArraySet<WebSocketServer> webSocketSet
= new CopyOnWriteArraySet<WebSocketServer>();
//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,必须
private Session session;
/**
* 连接建立成功调用的方法
*/
@OnOpen
public void onOpen(Session session) {
this.session = session;
webSocketSet.add(this); //将客户端加入set中
addOnlineCount(); //在线数加1
System.out.println("有新窗口开始监听,当前在线人数为"
+ getOnlineCount());
try {
sendMessage("连接成功");
} catch (IOException e) {
System.out.println("WebSocket IO异常");
}
}
/**
* 连接关闭调用的方法
*/
@OnClose
public void onClose() {
webSocketSet.remove(this); //从set中删除
subOnlineCount(); //在线数减1
System.out.println("有连接关闭！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(String message, Session session) {
System.out.println("收到客户端的信息:" + message);
//群发消息
for (WebSocketServer item : webSocketSet) {
try {
item.sendMessage(message);
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* @param session
* @param error
*/
@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 {
this.session.getBasicRemote().sendText(message);
}
/**
* 群发自定义消息
*/
public static void sendInfo(String message) throws IOException {
System.out.println("推送消息内容:" + message);
for (WebSocketServer item : webSocketSet) {
try {
item.sendMessage(message);
} catch (IOException e) {
continue;
}
}
}
public static synchronized int getOnlineCount() {
return onlineCount;
}
public static synchronized void addOnlineCount() {
WebSocketServer.onlineCount++;
}
public static synchronized void subOnlineCount() {
WebSocketServer.onlineCount--;
}
}
- Websocket控制层
@RestController
public class WebSocketController {
//推送数据接口
@GetMapping("/socket/push")
public String pushMsg(String message) {
try {
WebSocketServer.sendInfo(message);
} catch (IOException e) {
e.printStackTrace();
}
return "success";
}
}
- 前端调用
<html>
<head>
<meta charset="utf-8" />
<title>websocket示例</title>
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
</head>
<body>
<div id="app">
<h3>消息显示</h3>
<ul>
<li v-for="(message, index) in messages" :key="index">
{{message}}
</li>
</ul>
<hr>
<h3>发送消息 </h3>
<input type="text" v-model="sendMsg" />
<button type="button" @click="send">发送</button>
</div>
<script type="text/javascript">
var socket;
var app = new Vue({
el: '#app',
data: {
messages: [],
sendMsg: ''
},
created: function() {
var _this = this;
//创建WebSocket对象，指定要连接的服务器地址和端口，建立连接
socket = new WebSocket("ws://localhost:8080/websocket");
//打开连接
socket.onopen = function() {
console.log("Socket已打开");
};
//获得服务端推送的消息
socket.onmessage = function(msg) {
console.log(msg.data);
_this.messages.push(msg.data);
console.log(_this.messages);
};
//关闭连接
socket.onclose = function() {
console.log("Socket已关闭");
};
//发送错误
socket.onerror = function() {
alert("Socket发生了错误");
}
},
watch: {
// 如果 `messages` 发生改变，这个函数就会运行
messages: function(newMsg, oldMsg) {
this.messages = newMsg;
var n = new Notification('Title', {//标题
body : newMsg[newMsg.length - 1]
});
//两秒后关闭通知
setTimeout(function() {
n.close();
}, 2000);
},
},
methods: {
send: function() {
socket.send(this.sendMsg);
}
}
})
</script>
</body>
</html>
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