java程序如何穿透带有密码验证的代理

网上也有一些文章但是大多数涉及带有授权验证的proxy都有问题，
主要问题就是出在对 Authenticator.setDefault的使用，以及base64编码的问题上
代码是最没有二义性的文档，实现原理不再解释，请看代码去体会。
如果转载请注明代码出处。

Java sample codes that access outer internet through proxy which require username and password .Use inner instead of extends is the most different
chimae@cnjsp.org

package org.chimae.net;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.Authenticator;
import java.net.HttpURLConnection;
import java.net.PasswordAuthentication;
import java.net.URL;

/**
* @author chimae@cnjsp.org
*/
public class ProxyConnTest {

public static void initProxy(String host, int port, final String username,
final String password) {
Authenticator.setDefault(new Authenticator() {
protected PasswordAuthentication getPasswordAuthentication() {
return new PasswordAuthentication(username,
new String(password).toCharArray());
}
});


System.setProperty("http.proxyType", "4");
System.setProperty("http.proxyPort", Integer.toString(port));
System.setProperty("http.proxyHost", host);
System.setProperty("http.proxySet", "true");
}


public static void main(String[] args) throws IOException {
String url = "http://java.sun.com/";
String proxy = "yourProxy";
int port =8080;
String username ="username";
String password ="password";
String curLine = "";
String content = "";
URL server = new URL(url);
initProxy(proxy,port,username,password);
HttpURLConnection connection = (HttpURLConnection)server.openConnection();
connection.connect();
InputStream is = connection.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(is));
while ((curLine = reader.readLine()) != null) {
content += curLine;
}

System.out.println("content= " + content);
is.close();
}

}