java写一段websocket示例程序

好的，以下是一个简单的 Java WebSocket 示例程序：

import java.net.URI;
import java.net.URISyntaxException;
import java.util.Scanner;
import javax.websocket.ClientEndpoint;
import javax.websocket.CloseReason;
import javax.websocket.ContainerProvider;
import javax.websocket.OnClose;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.WebSocketContainer;

@ClientEndpoint
public class WebSocketClient {
    private Session session;

    @OnOpen
    public void onOpen(Session session) {
        this.session = session;
        System.out.println("Connected to server");
    }

    @OnMessage
    public void onMessage(String message) {
        System.out.println("Received message: " + message);
    }

    @OnClose
    public void onClose(CloseReason reason) {
        System.out.println("Disconnected from server: " + reason.getReasonPhrase());
    }

    public void sendMessage(String message) {
        this.session.getAsyncRemote().sendText(message);
    }

    public static void main(String[] args) throws URISyntaxException {
        WebSocketContainer container = ContainerProvider.getWebSocketContainer();
        String uri = "ws://localhost:808/websocket";
        WebSocketClient client = new WebSocketClient();
        container.connectToServer(client, new URI(uri));

        Scanner scanner = new Scanner(System.in);
        while (true) {
            String message = scanner.nextLine();
            client.sendMessage(message);
        }
    }
}

这个程序使用了 Java 的 WebSocket API，通过 `@ClientEndpoint` 注解标记一个 WebSocket 客户端类，然后实现 `OnOpen`、`OnMessage` 和 `OnClose` 方法来处理连接、消息和关闭事件。在 `main` 方法中，我们使用 `WebSocketContainer` 来连接到 WebSocket 服务器，然后通过 `Scanner` 读取用户输入，并通过 `sendMessage` 方法发送消息到服务器。