A connect failed: ECONNREFUSED (Connection denied) 很可能意味着在该端口和该 IP 地址上没有侦听任何内容.可能的解释包括:

A connect failed: ECONNREFUSED (Connection refused) most likely means that there is nothing listening on that port AND that IP address. Possible explanations include:

• 服务已崩溃或尚未(成功！)启动，
• 您的客户端正在尝试使用错误的 IP 地址或端口进行连接，
• 您的客户端正在尝试使用解析为错误 IP 的 DNS 名称进行连接，或者
• 服务器访问被代表服务器/服务拒绝"的防火墙阻止.这不太可能，因为通常的做法(现在)是让防火墙黑洞"所有不需要的连接尝试.

• the service has crashed or hasn't been (successfully!) started,
• your client is trying to connect using the wrong IP address or port,
• your client is trying to connect using a DNS name that resolves to the wrong IP, or
• server access is being blocked by a firewall that is "refusing" on the server/service's behalf. This is pretty unlikely given that normal practice (these days) is for firewalls to "blackhole" all unwanted connection attempts.

请注意，虽然您有一个名为 urls 的数组变量，但它不能包含真正的 URL.Socket 构造函数没有任何形式的真正 URL 的重载.事实上，如果你提供了一个像这样的字符串形式的 URL:

Note that while you have an array variable called urls, it cannot contain real URLs. There is no overload of the Socket constructor that takes a real URL in any form. Indeed, if you supplied a URL in string form like this:

 new Socket("http://example.com", 42)

结果将是一个不同的例外.同样，如果您尝试连接到无法路由到的网络上的 IP 地址(例如不同的 WiFi 网络")，那么您将收到不同的异常；例如找不到主机"、没有到主机的路由"或没有到网络的路由".

the result would be a different exception. Likewise, if you attempt to connect to an IP address on a network that you can't route to (e.g. "a different WiFi network"), then you will get a different exception; e.g. "host not found", "no route to host" or "no route to network".