尝试连接到套接字 io/express 服务器时出现 404 错误

Question

我在使用以下代码连接到套接字 io 和 express 服务器时遇到很多问题。我可以在浏览器中连接到网络 page/api，但是当我尝试从 index.html 连接到套接字连接时，我得到如下错误

这是我的'server.js'

var WebSocketServer = require('uws').Server,
    express         = require('express'),
    path            = require('path'),
    app             = express(),
    server          = require('http').createServer(),
    createEngine    = require('node-twig').createEngine;

app.engine('.twig', createEngine({
    root: __dirname + '/public',
}));

app.set('views', './public');
app.set('view engine', 'twig');

var cors = require('cors');
app.use(cors());

app.use(require('./routes'));
app.use(require('./api'));

app.use(express.static(path.join(__dirname, '/public')));

app.use("/admin", express.static(__dirname + '/public'));
app.use("/admin/scss", express.static(__dirname + '/scss'));
app.use("/admin/vendors", express.static(__dirname + '/vendors'));
app.use("/admin/js", express.static(__dirname + '/js'));
app.use("/admin/build", express.static(__dirname + '/build'));

app.use("/scss", express.static(__dirname + '/scss'));
app.use("/vendors", express.static(__dirname + '/vendors'));
app.use("/js", express.static(__dirname + '/js'));
app.use("/build", express.static(__dirname + '/build'));

var wss = new WebSocketServer({server: server});

wss.on('connection', function (ws) {

    ws.on('join', function () {
        console.log('SOMEONE JUST JOINED');
    });

    ws.on('close', function () {
        console.log('stopping client interval');
        clearInterval(id);
    });
});

server.on('request', app);

server.listen(8080, function () {
    console.log('Listening on http://localhost:8080');
});

这是我的 index.html 文件：

<script src="https://cdn.socket.io/socket.io-1.4.5.js"></script>

<script type="text/javascript">

var so = io.connect('http://192.168.***.***:8080/');

so.on('connect', () => {
    so.emit('join');
});

</scrip>

这是我不断收到的错误：

XMLHttpRequest cannot load http://localhost:8080/socket.io/?EIO=3&transport=polling&t=LfHXP1O. A wildcard '*' cannot be used in the 'Access-Control-Allow-Origin' header when the credentials flag is true. Origin 'http://192.168.4.149:8080' is therefore not allowed access. The credentials mode of an XMLHttpRequest is controlled by the withCredentials attribute.

有时我会收到此错误：

Failed to load resource: the server responded with a status of 404 (Not Found)

解决方案：

<script>
      var host = window.document.location.host.replace(/:.*/, '');
      var server = new WebSocket('ws://' + host + ':8080');
      server.onmessage = function (event) {
        updateStats(JSON.parse(event.data));
      };

      server.onopen = function (event) {};


    </script>

Answer 1

您正在尝试在客户端使用 socket.io 连接到 back-end 上的普通 webSocket 服务器。你不能那样做。 socket.io 是 webSocket 之上的一层，因此您需要使用普通 webSocket 连接到普通 webSocket 服务器，或者在客户端中使用 socket.io 连接到 socket.io 服务器back-end.

我建议您将服务器更改为使用 socket.io 作为 socket.io 服务器，而不是普通的 webSocket 服务器。

您收到的错误是因为 socket.io 客户端希望能够发出某个 http 请求，socket.io 服务器将处理该请求，但是由于您没有 socket.io 服务器，URL 请求未在服务器上处理。

尝试连接到套接字 io/express 服务器时出现 404 错误

Getting a 404 error when trying to connect to socket io/express server

node.js

http-status-code-404

socket.io