Java URL 类 openStream 抛出 java.net.ConnectException：连接被拒绝：连接
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Java URL class openStream throwing java.net.ConnectException: Connection refused: connect
提问by train5potting
I'm trying to write a simple program that displays the content of various URLS. My code is this.
我正在尝试编写一个简单的程序来显示各种 URL 的内容。我的代码是这样的。
import java.io.IOException;
import java.io.InputStream;
import java.net.*;
public class test {
public static void main(String[] args) {
URL url;
//String site ="ftp://ftp.suse.com/";
//String site ="http://www.google.ca";
//String site = "ftp://ftp.gnu.org/README";
String site = "ftp://metalab.unc.edu/";
try {
url = new URL(site);
InputStream stream = url.openStream();
for(int i = 0;i!= -1;i= stream.read()){
System.out.print((char)i);
}
stream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
The first 3 resources are fine
前3个资源没问题
- String site ="ftp://ftp.suse.com/";
- String site = "http://www.google.ca";
- String site = "ftp://ftp.gnu.org/README";
- 字符串站点 ="ftp://ftp.suse.com/";
- String site = "http://www.google.ca";
- String site = "ftp://ftp.gnu.org/README";
but the last one
但最后一个
- String site = "ftp://metalab.unc.edu/";
- String site = "ftp://metalab.unc.edu/";
produces the following error
产生以下错误
java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at sun.net.ftp.impl.FtpClient.openPassiveDataConnection(Unknown Source)
at sun.net.ftp.impl.FtpClient.openDataConnection(Unknown Source)
at sun.net.ftp.impl.FtpClient.list(Unknown Source)
at sun.net.www.protocol.ftp.FtpURLConnection.getInputStream(Unknown Source)
at java.net.URL.openStream(Unknown Source)
at test.main(test.java:13)
This also happens with various other ftp sites that I have tried as well. Haven't had any problems with HTTP sites. Any ideas what I can do to fix this. All the specified resources I can reach from my browser.
这也发生在我尝试过的其他各种 ftp 站点上。HTTP 站点没有任何问题。我能做些什么来解决这个问题的任何想法。我可以从浏览器访问的所有指定资源。
回答by skyuzo
It's possible that the site is refusing non-browser user agents. You can try setting the User-Agent:
该站点可能拒绝非浏览器用户代理。您可以尝试设置用户代理：
URL url;
String site = "ftp://metalab.unc.edu/";
try {
url = new URL(site);
URLConnection urlc = url.openConnection();
urlc.addRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0a2) Gecko/20110613 Firefox/6.0a2");
InputStream stream = urlc.getInputStream();
for(int i = 0;i!= -1;i= stream.read()){
System.out.print((char)i);
}
stream.close();
} catch (IOException e) {
e.printStackTrace();
}
回答by user714814
private static InputStream getStreamFromUrl(URL urlTemp) {
Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("http-pnproxy", 8080));
URLConnection uc;
InputStream inputStream = null;
URL url = null;
try {
url = urlTemp;
uc = (URLConnection)url.openConnection(proxy);
uc.addRequestProperty("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:6.0a2) Gecko/20110613 Firefox/6.0a2");
uc.connect();
inputStream = uc.getInputStream();
} catch (IOException e) {
e.printStackTrace();
}
return inputStream;
}
回答by Miquel
Long shot: could it be that your network firewall is selectively filtering where you can access, unless you use their proxy server?
远景：除非您使用他们的代理服务器，否则您的网络防火墙是否会选择性地过滤您可以访问的位置？
A quick test: change your browser config so it uses direct connection (no auto-proxy configuration or a given proxy), and just type in the url of the offending ftp server, see if it works.
快速测试：更改您的浏览器配置，使其使用直接连接（无自动代理配置或给定代理），然后只需输入有问题的 ftp 服务器的 url，看看它是否有效。
If it doesn't, that might be your problem, and you'll need to use a library that lets you specify a proxy, perhaps HttpCore.
如果没有，那可能是您的问题，您需要使用一个可以指定代理的库，可能是HttpCore。
If all else fails, install wireshark and see what on earth is happenning at the network level...
如果所有其他方法都失败了，请安装wireshark并查看网络级别到底发生了什么......
