java.net.Authenticator : java.net.ProtocolException: Server redirected too many times (20)

Question

We are calling URL using proxy settings via java standalone sample code on our weblogic servers (node1/node2). This code works fine on node 1 but same code doesn't work on node2 server. We already checked proxy settings and credentials all are fine but still we get following error :

 java.net.ProtocolException: Server redirected too many  times (20)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1323)
        at ProxyCode.start2(ProxyCode.java:54)
        at ProxyCode.main(ProxyCode.java:23)
Exception in thread "Main Thread" java.lang.NullPointerException
        at java.io.Reader.<init>(Reader.java:61)
        at java.io.InputStreamReader.<init>(InputStreamReader.java:55)
        at ProxyCode.readFromInputStream(ProxyCode.java:65)
        at ProxyCode.start2(ProxyCode.java:59)
        at ProxyCode.main(ProxyCode.java:22)

Also , Please find my code snippet below : SimpleAuthenticator.java

import java.net.Authenticator; import java.net.PasswordAuthentication;

public class SimpleAuthenticator extends Authenticator
{
        private String username;
        private String password;

        public SimpleAuthenticator(String username,String password)
        {
                this.username = username;
                this.password = password;
        }

        protected PasswordAuthentication getPasswordAuthentication()
        {
                return new PasswordAuthentication(
                        username,password.toCharArray());
        }
}

Main class :

    String url = "http://www.oracle.com/technetwork/java/readme-2-149793.txt";
    String proxy = "proxyserver";
    String port = "8080";
    String username = "username";
    String password = "password";
    Authenticator.setDefault(new SimpleAuthenticator(username,password));

    URL server = null;
    try {

            CookieHandler.setDefault(new CookieManager(null, CookiePolicy.ACCEPT_ALL));
            server = new URL(url);
    }
    catch (MalformedURLException e) {
            e.printStackTrace();
    }

Properties systemProperties = System.getProperties();
    systemProperties.setProperty("http.proxyHost", proxy);
    systemProperties.setProperty("http.proxyPort", port);

    InputStream in = null;
    URLConnection connection = null;

    try {
            connection = (URLConnection) server.openConnection();
            connection.connect();
            in = connection.getInputStream();
    }
    catch (IOException e) {
            e.printStackTrace();
    }
            System.out.println(readFromInputStream(in));
    }

    public static String readFromInputStream(InputStream in) {
            StringBuffer strBuf = new StringBuffer();
            char ac[];
            BufferedReader buf = new BufferedReader(new InputStreamReader(in));

      try 
     {
            while (buf.ready()) {
                    ac = new char[10000];
                    buf.read(ac);
                    strBuf.append(ac);
     }
            buf.close();
    }
    catch (IOException e) {
            e.printStackTrace();
    }

We are stuck in this since months now and not able to get any useful information anywhere. kindly help.thanks

Answer 1

You will get this error if you provide wrong credentials (username or password). This happened to me with a Glassfish based web app. I was expecting a 401 response however.

I think, the Authenticator tries the same credentials many times.

Answer 2

Found this open issue, still unfixed it would seem. Your user doesn't have access rights, but instead of prompting again it retries with the same user over and over

Update: The issue had another ticket open - this is apparently expected behaviour and

"To overcome this, your implementation of Authenticator::getPasswordAuthentication needs to provide a means to collect the correct password if the initial authentication attempt was not successful."

See the ticket or the java.net.Authenticator documentation for more info.