Websocket无法正常工作：意外响应代码404 [英] Websocket not working: unexpected responce code 404
问题描述
我正在尝试使用websockets创建javaee应用程序但是无法使程序正常工作。使用Tomcat 7，带有websockets的Java EE 7应用程序。
I am trying to create javaee application with websockets however can't get the program to work properly. Using Tomcat 7, Java EE 7 application with websockets.
这是我的java代码：
Here is my java code:
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);
}
}
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>
index.html：
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）;
websocket = new WebSocket(wsUri);
我得到：
与ws：// localhost：8080 / myapp / hello的Websocket连接失败：
意外的响应代码：404
Websocket connection to ws://localhost:8080/myapp/hello failed: Unexpected responce code: 404
我是否遗漏了web.xml或其他地方的内容？
Did I miss something in web.xml or somewhere else?
推荐答案
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。
WebSocket is implemented in Tomcat 7 by extending WebSocketServlet. But WebSocket 1.0 API introduced in tomcat 8. Your code is not compatible with Tomcat 7. Please make use of tomcat 8 and try the same.
更新...
现在，Tomcat7支持websocket，因为@samael说
Now, Tomcat7 supports websocket as @samael said
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