Question

I have created a Java Swing application. Some users can’t connect to the internet when activating the application, checking program updates, etc. because they are using a Proxy.

I have been reading about the interesting ProxySelector Class. It is very nice, but i have some questions about it please :

1. Will this class detect all types of Proxies that can be used(HTTP, HTTPS, FTP, SOCK,…) ?

2. If the Proxy used needs authentication, will this class get its information automatically ?

3. I have written code to get the Proxy settings used. Now i need to test this but i do not have a proxy, so i was going to set a proxy like the instructions here, but is there a faster method ? Can i use Public Proxies to test this like hidemyass.com ?

Answer 1

I can’t answer all your questions, but here some of them:

1.I belive that it will use the proxy selector for HTTP, HTTPS ans SOCKS. AFAIK, FTP is not natively supported by the JVM.

2.For Authentication, you can use the following code:

Authenticator.setDefault(new Authenticator() {
    private URL previous;
    int count = 0;
    @Override
    protected PasswordAuthentication getPasswordAuthentication() {
           try {
               if (previous == getRequestingURL())
                   count++;
               if (previous != getRequestingURL()) {
                   count = 0;
               } else {
                    if (count<3) {
                         // Ask for login/passwd to the user
                    } else {
                        // Throw a RuntimeException to prevent locking the account
                        throw new TooManyFailedAttemptException();
                    }

                   return new PasswordAuthentication("login", "password".toCharArray());
               }
          } finally {
               previous = getRequestingURL();
          }
    }
});

3.I guess that any public proxy is ok. I am not really sure on how you are going to ensure that your code is actually using it. Personally I set up a Squid proxy which is not that hard and there you can really trace your calls.