Java URL class openStream throwing java.net.ConnectException: Connection refused: connect

Question

I'm trying to write a simple program that displays the content of various URLS. My code is this.

    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

• String site ="ftp://ftp.suse.com/";
• String site = "http://www.google.ca";
• String site = "ftp://ftp.gnu.org/README";

but the last one

• String site = "ftp://metalab.unc.edu/";

produces the following error

    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.

Answer 1

It's possible that the site is refusing non-browser user agents. You can try setting the User-Agent:

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();
}

Answer 2

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;
    }