如何在Java中获得无代理连接? [英] How to get a proxy-less connection in Java?
问题描述
在与 URLConnection
建立连接时,如何避免通过 ProxySelector
,或者更确切地说如何获取连接保证没有Java知道的任何代理?
How do I avoid going through the ProxySelector
when making a connection with URLConnection
or rather how to get a connection guaranteed free of whatever proxies Java knows about ?
我认为这是 Proxy.NO_PROXY 用于。引自Javadoc:
I thought this was what Proxy.NO_PROXY was for. Quoting from the Javadoc:
代表DIRECT连接的代理设置,基本上告诉
协议处理程序不使用任何代理
A proxy setting that represents a DIRECT connection, basically telling the protocol handler not to use any proxying
然而,这样的连接仍将通过ProxySelector。我不明白吗?
Yet such a connection will still go through the ProxySelector. I don't get it ??
我做了一个小测试来证明我的观点:
I've made a small test to prove my point:
public static void main(String[] args) throws MalformedURLException, IOException {
ProxySelector.setDefault(new MyProxySelector());
URL url = new URL("http://foobar.com/x1/x2");
URLConnection connection = url.openConnection(Proxy.NO_PROXY);
connection.connect();
}
和一个虚拟的ProxySelector,除了记录正在发生的事情之外什么都不做:
and a dummy ProxySelector which does nothing but log what is going on:
public class MyProxySelector extends ProxySelector {
@Override
public List<Proxy> select(URI uri) {
System.out.println("MyProxySelector called with URI = " + uri);
return Collections.singletonList(Proxy.NO_PROXY);
}
@Override
public void connectFailed(URI uri, SocketAddress sa, IOException ioe) {}
}
打印:
"MyProxySelector called with URI = socket://foobar.com:80"
(注意如何协议已从 http
更改为套接字
)
(Note how the protocol has changed from http
to socket
)
我当然可以这样创建我的ProxySelector,以便它总是返回 Proxy.NO_PROXY
如果URI方案是 socket
但我想有可能在网站上有一个SOCKS代理,然后它就不会是真的。
I can of course create my ProxySelector in such a way so that it always returns Proxy.NO_PROXY
if the URI scheme is socket
but I guess there would be occasions where there's a SOCKS proxy on the site and then it wouldn't be true.
让我重申一个问题:我需要一个方法确保特定的 URLConnection
不使用代理,无论可以设置什么系统属性或安装什么ProxySelector。
Let me restate the question: I need a way to make sure a specific URLConnection
doesn't use a proxy, regardless of what System Properties may be set or what ProxySelector is installed.
推荐答案
这被跟踪为 JDK bug 8144008 。
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