一段java下载的程序参考

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Properties;


public class Down {

/**
* @param args
*/
  private static int downloaded; // number of bytes downloaded
  private static final int MAX_BUFFER_SIZE = 1024;
  private static int size; // size of download in bytes
public static void main(String[] args) throws Exception{
    downloaded = 0;
    size=0;
    String url = "http://ime.sogou.com/dl/sogou_pinyin_42l.exe";
        String proxy = "proxy.zte.com.cn";
        String hosturl  = url.substring(7, url.indexOf("/", 7));

        String requesturl  = url.substring(hosturl.length()+7);
       


     
        //URL url1 = new URL(proxy + requesturl);
        URL url1 = new URL(url);
        HttpURLConnection connection =
            (HttpURLConnection) url1.openConnection();
        //connection.setRequest