java.io.IOException：服务器返回 HTTP 响应代码：502
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java.io.IOException: Server returned HTTP response code: 502
提问by Ashfaq
i wrote a code which goes to a list of web addresses and get data from there. but when i run code some time code works mean goes to all web links and take data but some time i goes to 2 or 4 websites and get data and after them gives this exception followed by a web link form list.
我写了一个代码，它转到一个网址列表并从那里获取数据。但是当我运行代码时，有时代码工作意味着转到所有网络链接并获取数据，但有时我会转到 2 或 4 个网站并获取数据，然后在它们之后给出此异常，然后是网络链接表单列表。
java.io.IOException: Server returned HTTP response code: 502
java.io.IOException：服务器返回 HTTP 响应代码：502
but actually web link is alive not dead. when i run code for 2nd time then it runs but gives this exception for another link. code is too long thats why not posting it. if needed i can provide.
但实际上网页链接还活着而不是死了。当我第二次运行代码时，它会运行但为另一个链接提供此异常。代码太长这就是为什么不发布它。如果需要我可以提供。
Whats this excetption about?
这是什么异常？
采纳答案by Paul Draper
502 means "Bad Gateway". See http://www.checkupdown.com/status/E502.html.
502 的意思是“坏网关”。请参阅http://www.checkupdown.com/status/E502.html。
The server the Java client is talking to is the "gateway". That server was depending on another server (called the "upstream" server) to give it a response and it failed.
Java 客户端与之通信的服务器是“网关”。该服务器依赖于另一台服务器（称为“上游”服务器）来给它一个响应，但它失败了。
In my experience, 502 errors are sporadic, and can indicate problems with server architecture.
根据我的经验，502 错误是偶发的，可能表示服务器架构存在问题。
