Question

我正在尝试使用websockets创建javaee应用程序但是无法让程序正常工作。使用Tomcat 7，带有websockets的Java EE 7应用程序。

这是我的java代码：

import javax.websocket.CloseReason;
import javax.websocket.EndpointConfig;
import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.RemoteEndpoint;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;

@ServerEndpoint(value="/hello")
public class EchoEndpoint {
    RemoteEndpoint.Async endpoint;
    @OnOpen
    public void open(Session session, EndpointConfig conf) { 
        //Connection opened.
        System.out.println("EchoEndpoint on open");
        endpoint = session.getAsyncRemote(); 
    }

    @OnMessage
    public void onMessage(Session session, String msg) {
        //Message received.
        System.out.println("EchoEndpoint on message");
    }

    @OnError
    public void error(Session session, Throwable error) { 
        //Connection error.
        System.out.println("EchoEndpoint on error");
    }

    @OnClose
    public void close(Session session, CloseReason reason) { 
        //Connection closed.
        System.out.println("EchoEndpoint on close");
    }

    public void send(String string) {
        System.out.println("Send called to EchoEndpoint");
        endpoint.sendText(string);
    }
}

的web.xml：

<?xml version="1.0" encoding="UTF-8"?>

<web-app
        version="3.0"
        xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

</web-app>

的index.html：

<!DOCTYPE html>  
    <meta charset="utf-8" />  
    <title>WebSocket Test</title>  
    <script language="javascript" type="text/javascript">  
        var wsUri = "ws://localhost:8080/myapp/hello"; 
        var output;  
        function init() { 
            output = document.getElementById("output"); 
            testWebSocket(); 
        }  

        function testWebSocket() { 
            websocket = new WebSocket(wsUri);
            websocket.onopen = function(evt) { onOpen(evt) };
            websocket.onclose = function(evt) { onClose(evt) }; 
            websocket.onmessage = function(evt) { onMessage(evt) }; 
            websocket.onerror = function(evt) { onError(evt) }; 
        }  

        function onOpen(evt) { 
            writeToScreen("CONNECTED"); 
            doSend("WebSocket rocks"); 
        }  

        function onClose(evt) { 
            writeToScreen("DISCONNECTED"); 
        }  

        function onMessage(evt) { 
            writeToScreen('<span style="color: blue;">RESPONSE: ' + evt.data+'</span>'); 
            //websocket.close(); 
        }  

        function onError(evt) { 
            writeToScreen('<span style="color: red;">ERROR:</span> ' + evt.data); 
        } 

        function doSend(message) { 
            writeToScreen("SENT: " + message);  
            websocket.send(message); 
        }  

        function writeToScreen(message) { 
            var pre = document.createElement("p"); 
            pre.style.wordWrap = "break-word"; 
            pre.innerHTML = message; 
            output.appendChild(pre); 
        }  

        window.addEventListener("load", init, false);  
    </script>  

    <h2>WebSocket Test</h2>  
    <div id="output"></div>  
</html>

在客户端尝试执行：

websocket = new WebSocket（wsUri）;

我明白了：

与ws：// localhost：8080 / myapp / hello的Websocket连接失败：意外的响应代码：404

我是否遗漏了web.xml或其他地方的内容？

Answer 1

WebSocket通过扩展WebSocketServlet在Tomcat 7中实现。但是在tomcat 8中引入了WebSocket 1.0 API。您的代码与Tomcat 7不兼容。请使用tomcat 8并尝试相同。

...更新

现在，Tomcat7支持websocket，如@samael所说

Websocket无法正常工作：意外的响应代码404

1 个答案: