Question

使用socket.io v1.3.2时出现传输错误。它只是为了测试socket.io所以我可以熟悉它。

我有一个文件app.js（直接来自socket.io docs）：

var app = require('http').createServer(handler);
var io = require('socket.io')(app);
var fs = require('fs');

app.listen(3000);

function handler (req, res) {
  fs.readFile(__dirname + '/index.html',
  function (err, data) {
    if (err) {
      res.writeHead(500);
      return res.end('Error loading index.html');
    }

    res.writeHead(200);
    res.end(data);
  });
}

io.on('connection', function (socket) {
  socket.emit('news', { hello: 'world' });
});

文件index.html：

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title></title>
    <link rel="stylesheet" href="">
</head>
<body>
    <h1>Socket Test</h1>
    <script src="/socket.io/socket.io.js"></script>
    <script>
        var socket = io.connect('http://localhost');
        socket.on('news', function (data) {
            console.log(data);
        });
    </script>

</body>
</html>

在控制台中，我收到以下错误：

GET http://localhost/socket.io/?EIO=3&transport=polling&t=1422782880286-40 
(index):1 XMLHttpRequest cannot load http://localhost/socket.io/?EIO=3&transport=polling&t=1422782880286-40. No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:3000' is therefore not allowed access. The response had HTTP status code 404.
socket.io.js:3715 engine.io-client:socket socket error {"type":"TransportError","description":0} +37ms
socket.io.js:1402 socket.io-client:manager connect_error +38ms
socket.io.js:1402 socket.io-client:manager reconnect attempt error +1ms
socket.io.js:1402 socket.io-client:manager will wait 5000ms before reconnect attempt +0ms
socket.io.js:3715 engine.io-client:socket socket close with reason: "transport error" +2ms
socket.io.js:3715 engine.io-client:polling transport not open - deferring close +1ms
socket.io.js:1402 socket.io-client:manager attempting reconnect +5s
socket.io.js:1402 socket.io-client:manager readyState closed +0ms
socket.io.js:1402 socket.io-client:manager opening http://localhost +0ms
socket.io.js:3715 engine.io-client:socket creating transport "polling" +5s
socket.io.js:3715 engine.io-client:polling polling +0ms
socket.io.js:3715 engine.io-client:polling-xhr xhr poll +0ms
socket.io.js:3715 engine.io-client:polling-xhr xhr open GET: http://localhost/socket.io/?EIO=3&transport=polling&t=1422782885332-41 +1ms
socket.io.js:3715 engine.io-client:polling-xhr xhr data null +0ms
socket.io.js:3715 engine.io-client:socket setting transport polling +1ms
socket.io.js:1402 socket.io-client:manager connect attempt will timeout after 20000 +3ms

有谁知道如何解决此错误。我找到了this discussion，但一直无法解决问题。

Answer 1

您的代码与socket.io网站上的示例之间的区别在于socket.io示例代码正在侦听端口80并在端口80上连接webSocket。您正在侦听端口3000，但正在尝试在端口80上连接，因此连接不起作用。 io.connect('http://localhost');未指定端口号，因此它将使用默认的http端口，即端口80.但是，您的websocket服务器未在端口80上侦听，因此连接失败。

解决此问题的最简单方法是更改客户端中的代码行：

var socket = io.connect('http://localhost');

到此：

var socket = io.connect();

当您省略URL时，默认情况下，它将使用当前网页中的域和端口（这是您想要的）。

Answer 2

默认情况下，localhost端口为80.您将客户端的套接字连接到localhost而不声明端口。因此默认情况下它为您提供了端口80，并且您的节点服务器正在侦听端口3000.为了让您的客户端连接到您的服务器，您必须声明服务器侦听的端口。示例：var socket = io.connect（'http://localhost:3000'）;

使用Socket.Io传输轮询错误

2 个答案: