javascript 为什么我的 WebSocket 会自动关闭？
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Why is my WebSocket automatically closing?
提问by mavix
I've set up a very basic websocket server using tornado:
我已经使用 Tornado 设置了一个非常基本的 websocket 服务器：
import tornado.ioloop
import tornado.web
import tornado.websocket
import tornado.httpserver
class WSHandler(tornado.websocket.WebSocketHandler):
def open(self):
print 'new connection'
self.write_message("Hello World")
def on_message(self, message):
print 'message received %s' % message
def on_close(self):
print 'connection closed'
application = tornado.web.Application([
(r'/ws', WSHandler),
])
if __name__ == "__main__":
http_server = tornado.httpserver.HTTPServer(application)
http_server.listen(8000)
tornado.ioloop.IOLoop.instance().start()
and a very basic client, that should be able to continually ping the server via a button click:
和一个非常基本的客户端，它应该能够通过单击按钮不断地 ping 服务器：
<!DOCTYPE html>
<meta charset="utf-8" />
<title>WebSocket Test</title>
<script language="javascript" type="text/javascript">
var wsUri = "ws://localhost:8000/ws";
var websocket = new WebSocket(wsUri);
var output;
function init() {
output = document.getElementById("outputDiv");
if (!'WebSocket' in window){
writeToScreen('<span style="color: red;">ERROR: Update your browser to one that supports websockets. A list can be found <a href="http://caniuse.com/websockets">here</a></span>');
} else {
testWebSocket();
}
}
function onOpen(evt) {
writeToScreen("CONNECTED");
doSend("Hi there!");
}
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);
}
function testWebSocket() {
websocket.onopen = function(evt) { onOpen(evt) };
websocket.onclose = function(evt) { onClose(evt) };
websocket.onmessage = function(evt) { onMessage(evt) };
websocket.onerror = function(evt) { onError(evt) };
document.getElementById("send").onclick = function () {
doSend(document.getElementById("inputTxt").value);
console.log("click registered.");
};
}
window.addEventListener("load", init, false);
</script>
</div>
<h2>WebSocket Test</h2>
<div id="inputDiv">
<input id="inputTxt" type="text"/>
<button id="send" onclick=>send</button>
</div>
<div id="outputDiv">
</div>
</html>
When I load the page, I get:
当我加载页面时，我得到：
CONNECTED
SENT: Hi there!
RESPONSE: Hello World
DISCONNECTED
已连接
：您好！
响应：Hello World 已
断开连接
If I click the button, I get an error:
如果我单击该按钮，则会收到错误消息：
WebSocket is already in CLOSING or CLOSED state.
WebSocket 已经处于 CLOSING 或 CLOSED 状态。
But, if I re-instantiate the websocket object in the command line (via chrome developer tools), the button works, and the connection is not closed. I feel that this must be some idiosyncrasy of javascript that I don't understand, because if the object is still in scope, I don't understand why it would have automatically closed the connection.
但是，如果我在命令行中重新实例化 websocket 对象（通过 chrome 开发人员工具），按钮会起作用，并且连接不会关闭。我觉得这一定是我不明白的 javascript 特性，因为如果对象仍在范围内，我不明白为什么它会自动关闭连接。
采纳答案by mavix
Derp. The onMessage function is closing it:
德普。onMessage 函数正在关闭它：
function onMessage(evt) {
writeToScreen('<span style="color: blue;">RESPONSE: ' + evt.data+'</span>');
websocket.close();
}
