項目中碰到從後臺實時接收通知然後語音播放的需求，以前項目中調用過別人寫的websocket接口，這次自己寫了一下，分享下：
1.依賴的引入
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-websocket</artifactId>
<version>1.5.3.RELEASE</version>
<type>pom</type>
</dependency>
以上是springboot工程的引入，如果是普通的war包部署tomcat可以如下配置：
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-api</artifactId>
<version>7.0</version>
<scope>provided</scope>
</dependency>
2.聲明註冊使用@ServerEndpoint 註解，
@Configuration
public class WebSocketConfig {
@Bean
public ServerEndpointExporter serverEndpointExporter(){
return new ServerEndpointExporter();
} }
3.寫服務類
@ServerEndpoint(value = "/websocket") //接受websocket請求路徑
@Component //註冊到spring容器中
public class AlarmWebSocket {
//保存所有在線socket連接
private static Map<String,AlarmWebSocket> webSocketMap = new LinkedHashMap<>();
//記錄當前在線數目
private static int count=0;
//當前連接（每個websocket連入都會創建一個MyWebSocket實例
private Session session;
private Logger log = LoggerFactory.getLogger(this.getClass());
//處理連接建立
@OnOpen
public void onOpen(Session session){
this.session=session;
webSocketMap.put(session.getId(),this);
addCount();
log.info("新的連接加入：{}",session.getId());
}
//接受消息
@OnMessage
public void onMessage(String message,Session session){
log.info("收到客戶端{}消息：{}",session.getId(),message);
try{
this.sendMessage("收到消息："+message);
}catch (Exception e){
e.printStackTrace();
}
}
//處理錯誤
@OnError
public void onError(Throwable error,Session session){
log.info("發生錯誤{},{}",session.getId(),error.getMessage());
}
//處理連接關閉
@OnClose
public void onClose(){
webSocketMap.remove(this.session.getId());
reduceCount();
log.info("連接關閉:{}",this.session.getId());
}
//羣發消息
//發送出去消息
public void sendMessage(String message) throws IOException {
this.session.getBasicRemote().sendText(message);//這裏可以寫死字符串測試
}
//廣播消息
public static void broadcast(String message){
AlarmWebSocket.webSocketMap.forEach((k,v)->{
try{
v.sendMessage(message);
}catch (Exception e){
}
});
}
//獲取在線連接數目
public static int getCount(){
return count;
}
//操作count，使用synchronized確保線程安全
public static synchronized void addCount(){
AlarmWebSocket.count++;
}
public static synchronized void reduceCount(){
AlarmWebSocket.count--;
}
}
4.前端建立連接及發送消息測試
<html>
<head> <title>websocket測試</title> <meta charset="utf-8" /> </head>
<body>
<button οnclick="sendMessage()">測試</button>
<script>
let socket = new WebSocket("ws://localhost:8080/websocket");
socket.onerror = err => { console.log(err); };
socket.onopen = event => { console.log(event); };
socket.onmessage = mess => { console.log(mess); };
socket.onclose = () => { console.log("連接關閉"); };
function sendMessage() {
if (socket.readyState === 1) socket.send("這是向後臺發送的測試數據");
else alert("還沒成功建立websocket連接"); }
</script> </body> </html>
5.如果前臺沒問題，後臺測試發送給前臺消息
@RestController
public class TestController {
@GetMapping("/broadcast")
public void broadcast(){ MyWebSocket.broadcast();
} }
在瀏覽器F12打開前端日誌，觀察websocket狀態，打印：
Event {isTrusted: true, type: "open", target: WebSocket, currentTarget: WebSocket, eventPhase: 2, …}
type狀態是open表示成功建立websocket連接，後臺發送給前端消息，也可以打印出日誌