如何在碼頭容器中設置JSR356 WebSockets

Question

我看到很多關於如何使用某種嵌入式Web服務器設置JSR356 Web套接字的教程。

但是我想在部署到獨立碼頭設備jetty jetty-9.2.3.v20140905的現有WAR中添加一些Websocket，在此方面我幾乎找不到任何信息。 我不知道是什么阻止了它的工作。 據我了解，帶注釋的服務器端點應該由碼頭自動處理。

ServerEndpoint：

    @ServerEndpoint(value = "/myendpoint")
public class MyServerEndpoint {     
    private Logger logger = Logger.getLogger(this.getClass().getName());     

    @OnOpen 
    public void onOpen(Session s) {
        logger.info("Server Connected ... " + s.getId());
        s.getAsyncRemote().sendText("You are connected to the websocket server");   
    }        

    @OnMessage  
    public void onMessage(String message, Session session) {

        // Sent the message back to all connected users             
        logger.info("Server Session " + session + " Received string message " + message);

        for(Session s: session.getOpenSessions()) {     
            if (s.isOpen()) { 
                s.getAsyncRemote().sendText(message + " server response");
            }       
        }   
    }        

    @OnClose    
    public void onClose(Session session, CloseReason reason) {
        logger.info("Server Session " + session + " closed for reason " + reason);
    }   
}

ClientEndpoint：

    @ClientEndpoint
public class MyClientEndpoint {     
    private Logger logger = Logger.getLogger(this.getClass().getName());     

    @OnOpen 
    public void onOpen(Session s) {
        logger.info("Client Connected ... " + s.getId());
        s.getAsyncRemote().sendText("hello from the client!");  
    }        

    @OnMessage  
    public void onMessage(String message, Session session) {

        logger.info("Client Session " + session + " Received string message " + message);       

    }        

    @OnClose    
    public void onClose(Session session, CloseReason reason) {
        logger.info("Client Session " + session + " closed for reason " + reason);
    }   
}

這是將客戶端連接到服務器的代碼（在某些現有方法中運行）

    WebSocketContainer container = ContainerProvider.getWebSocketContainer();
    String uri = "ws://localhost:8080/myWar/myendpoint"; 
    container.connectToServer(MyClientEndpoint.class, URI.create(uri));

但是旋轉碼頭會在connectToServer線上產生錯誤

2014-10-30 12:26:58.658:WARN:oeja.ServletContainerInitializersStarter:main: 
org.eclipse.jetty.websocket.api.InvalidWebSocketException: Unable to instantiate websocket: class java.lang.Class
at   org.eclipse.jetty.websocket.jsr356.ClientContainer.newClientEndpointInstance(ClientContainer.java:311)
    at org.eclipse.jetty.websocket.jsr356.ClientContainer.connectToServer(ClientContainer.java:172)

我只能認為URI不正確。 如果jetty在8080上運行，而我的.war被命名為myWar，而我的端點被命名為myendpoint ...那不是正確的URI嗎？

是否需要執行一些其他步驟來“激活”服務器端點以偵聽連接？ 我一定想念一些明顯的東西。

Answer 1

奇怪的是，您的錯誤消息。

org.eclipse.jetty.websocket.api.InvalidWebSocketException: 
  Unable to instantiate websocket: class java.lang.Class

意味着將websocket實現傳遞給原始java.lang.Class進行實例化。 那是行不通的。

這也意味着沒有嘗試進行連接，因為WebSocket類本身很糟糕，無法進行連接。

這是一個簡短（有效且有效）的示例，展示了其用法。

package jetty.jsr356;

import java.io.IOException;
import java.net.URI;
import java.util.concurrent.CountDownLatch;

import javax.websocket.ClientEndpoint;
import javax.websocket.CloseReason;
import javax.websocket.CloseReason.CloseCodes;
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 TestClientAnnotatedClass
{
    private static CountDownLatch closeLatch = new CountDownLatch(1);

    @OnOpen
    public void onOpen(Session session)
    {
        System.out.println("@OnOpen - " + session);
        try
        {
            session.getBasicRemote().sendText("Rock it with Java WebSocket");
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }

    @OnMessage
    public void onMessage(Session session, String msg)
    {
        System.out.println("@OnMessage - ["+msg+"]");
        try
        {
            session.close(new CloseReason(CloseCodes.NORMAL_CLOSURE,"Thanks"));
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }

    @OnClose
    public void onClose(CloseReason close)
    {
        System.out.println("@OnClose - " + close);
        closeLatch.countDown();
    }

    public static void main(String[] args)
    {
        try
        {
            WebSocketContainer ws = ContainerProvider.getWebSocketContainer();

            ws.connectToServer(TestClientAnnotatedClass.class,new URI("ws://echo.websocket.org/?encoding=text"));
            closeLatch.await();
        }
        catch (Throwable t)
        {
            t.printStackTrace();
        }
    }
}

您將看到類似於此的輸出

2014-10-30 11:34:19.197:INFO::main: Logging initialized @71ms
@OnOpen - WebSocketSession[websocket=JsrAnnotatedEventDriver[websocket=jetty.jsr356.TestClientAnnotatedClass@5cca5f2c],behavior=CLIENT,connection=WebSocketClientConnection@6a2e714b{IDLE}{f=Flusher[queueSize=0,aggregateSize=0,failure=null],g=Generator[CLIENT,validating],p=Parser@55465b1f[ExtensionStack,s=START,c=0,len=0,f=null,p=WebSocketPolicy@7e087bf5[behavior=CLIENT,maxTextMessageSize=65536,maxTextMessageBufferSize=32768,maxBinaryMessageSize=65536,maxBinaryMessageBufferSize=32768,asyncWriteTimeout=60000,idleTimeout=300000,inputBufferSize=4096]]},remote=WebSocketRemoteEndpoint@5f025277[batching=true],incoming=JsrAnnotatedEventDriver[websocket=jetty.jsr356.TestClientAnnotatedClass@5cca5f2c],outgoing=ExtensionStack[queueSize=0,extensions=[],incoming=org.eclipse.jetty.websocket.jsr356.JsrSession,outgoing=org.eclipse.jetty.websocket.client.io.WebSocketClientConnection]]
@OnMessage - [Rock it with Java WebSocket]
@OnClose - CloseReason[1000,Thanks]

Answer 2

Jetty使用反射創建帶注釋的客戶端端點的實例（請參見/ jetty / websocket / jsr356 / ClientContainer＃newClientEndpointInstance（） ），但是Java無法以這種方式實例化非靜態內部類 。 實際的原因異常類似於java.lang.NoSuchMethodException: <pkg>.OuterClass$InnerClass.<init>()但已被吞下。

解決方案：帶注釋的終結點類不應是嵌套的或嵌套的靜態（內部）類。