java实现websocket实现消息推送

Java实现WebSocket实现消息推送的步骤如下：

1.创建WebSocket配置类

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(new MyWebSocketHandler(), "/websocket").addInterceptors(new MyHandshakeInterceptor());
    }
}

2.创建WebSocket处理器

public class MyWebSocketHandler extends TextWebSocketHandler {
    private static final List<WebSocketSession> sessions = new CopyOnWriteArrayList<>();

    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {
        sessions.add(session);
    }

    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        for (WebSocketSession s : sessions) {
            s.sendMessage(message);
        }
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) throws Exception {
        sessions.remove(session);
    }
}

3.创建握手拦截器

public class MyHandshakeInterceptor implements HandshakeInterceptor {
    @Override
    public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object> attributes) throws Exception {
        return true;
    }

    @Override
    public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception exception) {
    }
}

4.在页面中使用JavaScript连接WebSocket

var socket = new WebSocket("ws://localhost:8080/websocket");
socket.onmessage = function(event) {
    console.log(event.data);
};