java.net.URL如何通过proxy访问internet资源

import java.util.Properties;

import java.net.*;

import java.io.*;

public class TestHttpProxy {

public static void main(String[] args) {

String sUrl = "http://java.sun.com/index.html";

Properties prop = System.getProperties();

prop.put("http.proxyHost","192.168.1.111");

prop.put("http.proxyPort","80");

try{

URL su = new URL(sUrl);

System.out.println("url : "   su);

URLConnection uc = su.openConnection();

System.out.println("uc : "   uc);

InputStream is = su.openStream();

System.out.println("ic : "   is.read());

is.close();

System.out.println("ok");

} catch(Exception e) {

e.printStackTrace();

}

}

}