Simple Websocket Client in Java - Connection issue
I found the issue - it was that the ws address required a '/' on the end of it when being run from a java client.
JavaScript ws://192.168.0.25:9000
Java ws://192.168.0.25:9000/
Not sure why this is required in Java - but it solved the issue...
flinthart
Updated on July 09, 2022Comments
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flinthart almost 2 years
I'm trying to write a simple websocket client in Java to connect to a 3rd party WebSocket server (I have no access to the server).
I can connect and communicate with the websocket server using javascript in a browser, but when I try and do the same thing using a Java client it fails to connect.
With the same java client I can connect to a tomcat websocket server I have running, so I think it's some sort of compatibility issue between the client and server. (I'm using Tomcat 7.0.56 libraries for the websocket client).
This is the error I get...
Error
javax.websocket.DeploymentException: The HTTP request to initiate the WebSocket connection failed at org.apache.tomcat.websocket.WsWebSocketContainer.connectToServer(WsWebSocketContainer.java:344) at org.apache.tomcat.websocket.WsWebSocketContainer.connectToServer(WsWebSocketContainer.java:166) at com.cvr.instant.ws.WebSocketClient.Connect(WebSocketClient.java:44) at com.cvr.instant.ws.TestWS.Start(TestWS.java:17) at com.cvr.instant.ws.TestWS.main(TestWS.java:37) Caused by: java.io.EOFException at org.apache.tomcat.websocket.WsWebSocketContainer.processResponse(WsWebSocketContainer.java:595) at org.apache.tomcat.websocket.WsWebSocketContainer.connectToServer(WsWebSocketContainer.java:317) ... 4 more
WebSocketClient
import java.io.IOException; import java.net.URI; import java.net.URISyntaxException; import javax.websocket.ClientEndpoint; import javax.websocket.CloseReason; import javax.websocket.ContainerProvider; import javax.websocket.DeploymentException; import javax.websocket.OnClose; import javax.websocket.OnMessage; import javax.websocket.OnOpen; import javax.websocket.Session; import javax.websocket.WebSocketContainer; @ClientEndpoint public class WebSocketClient { protected WebSocketContainer container; protected Session userSession = null; public WebSocketClient() { container = ContainerProvider.getWebSocketContainer(); } public void Connect(String sServer) { try { userSession = container.connectToServer(this, new URI(sServer)); } catch (DeploymentException | URISyntaxException | IOException e) { e.printStackTrace(); } } public void SendMessage(String sMsg) throws IOException { userSession.getBasicRemote().sendText(sMsg); } @OnOpen public void onOpen(Session session) { System.out.println("Connected"); } @OnClose public void onClose(Session session, CloseReason closeReason) { } @OnMessage public void onMessage(Session session, String msg) { System.out.println(msg); } public void Disconnect() throws IOException { userSession.close(); } }
Running the client
import java.io.IOException; public class TestWS { public WebSocketClient wsc; public TestWS() { } public void Start() throws InterruptedException, IOException { wsc = new WebSocketClient(); wsc.callback = this; wsc.Connect("ws://192.168.0.25:9000"); Thread.sleep(1000); wsc.Disconnect(); } public static void main(String[] args) throws InterruptedException, IOException { TestWS t = new TestWS(); t.Start(); Thread.sleep(1000); } }
I'm very new to websocket clients (and fairly new to websockets in general). Any help you can give would be appreciated!