Tomcat WebSocket錯誤

Question

我跟着這個link來製作使用tomcat的websocket服務器。 當我試圖訪問WebSocket時，我的Firefox說它無法建立連接。

這裏是我的代碼

public class WsChatServlet extends WebSocketServlet 
{ 
private static final long serialVersionUID = 1L; 
private static ArrayList<MyMessageInbound> mmiList = new ArrayList<MyMessageInbound>(); 

@Override 
protected StreamInbound createWebSocketInbound(String string) { 
    System.out.println("CreateWebSocketInbound()"); 
    return new MyMessageInbound(); 
} 

private class MyMessageInbound extends MessageInbound 
{ 
    WsOutbound myoutbound; 

    @Override 
    protected void onBinaryMessage(ByteBuffer bb) throws IOException { 
     System.out.println("onBinaryMessage()"); 
    } 

    @Override 
    protected void onTextMessage(CharBuffer cb) throws IOException {    
     System.out.println("Accept Message : "+ cb); 
     for (MyMessageInbound mmib : mmiList) 
     { 
      CharBuffer buffer = CharBuffer.wrap(cb); 
      mmib.myoutbound.writeTextMessage(CharBuffer.wrap("Hello!")); 
      mmib.myoutbound.flush(); 
     } 
    } 

    @Override 
    protected void onOpen(WsOutbound outbound) { 
     System.out.println("onOpen()"); 
     try { 
      System.out.println("Open Client."); 
      this.myoutbound = outbound; 
      mmiList.add(this); 
      outbound.writeTextMessage(CharBuffer.wrap("Hello!")); 
     } catch (IOException ex) { 
      Logger.getLogger(WsChatServlet.class.getName()).log(Level.SEVERE, null, ex); 
     } 
    } 

    @Override 
    protected void onClose(int status) { 
     System.out.println("Close Client."); 
     mmiList.remove(this); 
    } 
} 

這裏是服務器日誌

24 Apr 13 22:53:09 org.apache.catalina.core.StandardWrapperValve invoke 
SEVERE: Servlet.service() for servlet [WsChatServlet] in context with path [/HelloWebSocket] threw exception 
java.lang.ClassCastException: org.netbeans.modules.web.monitor.server.MonitorRequestWrapper cannot be cast to org.apache.catalina.connector.RequestFacade 
    at org.apache.catalina.websocket.WebSocketServlet.doGet(WebSocketServlet.java:126) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) 
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
    at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169) 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98) 
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) 
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999) 
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565) 
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) 
    at java.lang.Thread.run(Thread.java:662) 

如何解決這個問題，以及如何使內碼格式的日誌？

Answer 1

檢查你的tomcat版本。 Websocket不是標準的，不同的服務器對websocket有不同的實現。我曾經使用過tomcat的websockets，它只能用於tomcat 7.0.27。即使7.0.29也沒有工作。所以我建議檢查一下你是否可以找到你的教程使用了哪個服務器，或者嘗試不同的版本。

Answer 2

這是Tomcat 7.0.27中的一個錯誤。我建議你使用7.0.37，或者使用類似Atmosphere框架（會從這樣的問題被屏蔽）

- Jeanfrancois