java发送websocket请求

Java可以使用Java WebSocket API来发送WebSocket请求。以下是一个简单的示例代码，可以使用Java WebSocket API连接到WebSocket服务器并发送消息：

import java.net.URI;
import java.net.URISyntaxException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
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 final CountDownLatch latch;
    private Session session;

    public WebSocketClient() {
        this.latch = new CountDownLatch(1);
    }

    public void connect(String uri) throws Exception {
        WebSocketContainer container = ContainerProvider.getWebSocketContainer();
        container.connectToServer(this, new URI(uri));
        latch.await(10, TimeUnit.SECONDS);
    }

    @OnOpen
    public void onOpen(Session session) {
        this.session = session;
        latch.countDown();
    }

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

    @OnClose
    public void onClose(Session session, CloseReason closeReason) {
        System.out.println("WebSocket closed: " + closeReason);
    }

    public void sendMessage(String message) throws Exception {
        session.getBasicRemote().sendText(message);
    }

    public static void main(String[] args) throws Exception {
        WebSocketClient client = new WebSocketClient();
        client.connect("ws://localhost:8080/websocket");
        client.sendMessage("Hello, WebSocket!");
    }
}

在上面的示例代码中，我们定义了一个`WebSocketClient`类，它实现了`javax.websocket.ClientEndpoint`接口。我们使用`WebSocketContainer`来连接到WebSocket服务器并发送消息。`@OnOpen`注解用于在连接建立时调用的方法，`@OnMessage`注解用于接收消息时调用的方法，`@OnClose`注解用于在连接关闭时调用的方法。我们可以使用`Session`对象来发送WebSocket消息。在`main`方法中，我们创建一个`WebSocketClient`对象并连接到WebSocket服务器，然后发送消息。