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。

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();
}

}