java使用代理访问网络

在使用java的net包访问网络时，如果需要使用代理，可以这样做：

System.getProperties().setProperty("proxySet", "true");
System.getProperties().setProperty("http.proxyHost", "183.121.23.188");
System.getProperties().setProperty("http.proxyPort", "8080");

URL url = new URL(http://www.163.com);
HttpURLConnection httpConn = (HttpURLConnection)url.openConnection();
HttpURLConnection.setFollowRedirects(true);
httpConn.setRequestMethod("GET");
httpConn.setRequestProperty("User-Agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows 2000)");
InputStream in = httpConn.getInputStream();
BufferedReader myBufferedReader=new BufferedReader(new InputStreamReader(in));
String myString=null;
while((myString=myBufferedReader.readLine())!=null){
    System.out.println(myString);
}

其中，前三行就是设置代理的语句。