Problemas com autenticação em proxy

import java.net.*; 
import com.sun.net.ssl.*; 
import java.io.*; 
import sun.misc.BASE64Encoder; 
import java.security.*; 

public class PassProxy { 

  public PassProxy(String proxyhost, String proxyport, String proxylogin,  String proxypass, String url) { 

   /* Set the proxy server host and port */ 
   
   System.setProperty("http.proxyHost", proxyhost); 
   
   System.setProperty("http.proxyPort", proxyport); 

	byte[] encodedPassword = (proxylogin+":"+proxypass).getBytes(); 
	
	BASE64Encoder encoder = new BASE64Encoder(); 
    try 
    { 
          URL u = new URL(url); 
          HttpURLConnection uc = (HttpURLConnection)u.openConnection(); 
     
          uc.setRequestProperty("Authorization","Basic " +encoder.encode(encodedPassword));  
          uc.connect(); 
          //uc.setRequestMethod( "POST" ); 
          System.out.println("iahaaaa");
         //uc.setDoInput( true ); 
         /* Print the content of the url to the console. */ 
         showContent(uc);
       
   } catch (IOException e) { 
   	System.out.println("exception da conex");	
     e.printStackTrace(); 
   } 
  } 

  private void showContent(HttpURLConnection uc) throws IOException { 
   InputStream i = uc.getInputStream(); 
   char c; 
   InputStreamReader isr = new InputStreamReader(i); 
   BufferedReader br = new BufferedReader(isr); 
   String line; 
   while ((line = br.readLine()) != null) { 
     System.out.println(line); 
   } 
  } 

  public static void main(String[] args) { 
    
     String proxyhost = "172.17.78.8"; 
     String proxyport = "80"; 
     String proxylogin = "login"; 
     String proxypass = "pass"; 
     String url = "http://www.qualquersite.com.br"; 
     
     new PassProxy(proxyhost, proxyport, proxylogin, proxypass, url); 
    
  }
  }