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。