完整代码
package ;//导入编码的jar文件import it.sauronsoftware.base64.Base64;import java.io.BufferedInputStream;import java.io.BufferedReader;import java.io.InputStreamReader;import .HttpURLConnection;import .URL;/*** 很多公司会对网上进行限制，要通过代理服务器和口令才能连接外网。<br>* 这种方式有很多好处：<br>* 1、安全，代理服务器像一层过滤层；<br>* 2、节省成本，只需要分配很少的IP地址即可；<br>* 3、对员工上网可以个性化配置，避免有人下载大量数据而造成网络拥堵不堪。<br>* * 本文通过一个小案例来介绍如何在程序里跨过局域网访问外网。<br>* 对于搞网络开发的人来说，不值一提；但对于做JAVA EE应用开发的人来说，可以参考。<br>* * @author 王一洋* * -10-30* */public class Test {public static void main(String[] args) {try {//两种方式设置代理服务器//设置代理1//Proxy proxy = new Proxy(Proxy.Type.HTTP,new InetSocketAddress("", 80));//设置代理2System.getProperties().setProperty( "http.proxyHost", "");System.getProperties().setProperty( "http.proxyPort", "" );String urlString = "/";URL url = new URL(urlString);//对应第一种设置方式//HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(proxy);HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();urlConnection.setRequestMethod("GET");urlConnection.setConnectTimeout(1000);//设置User AgenturlConnection.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");//设置访问的用户名和密码urlConnection.setRequestProperty( "Proxy-Authorization", "Basic" + Base64.encode("username:password") );urlConnection.connect();System.out.print(urlConnection.getResponseCode());BufferedInputStream bis = new BufferedInputStream(urlConnection.getInputStream());InputStreamReader isr = new InputStreamReader(bis,"UTF-8");BufferedReader bufferedReader = new BufferedReader(isr);String str = "";StringBuffer buffer = new StringBuffer("");while((str = bufferedReader.readLine())!=null){buffer.append(str+"\r\n");}System.out.println(buffer);} catch (Exception e) {e.printStackTrace();}}}
返回code：200，OK！
异常Server returned HTTP response code: 403 for URL
在url.openConnection()后添加：
connection.setRequestProperty("User-Agent","Mozilla/4.0(compatible;MSIE5.0;WindowsNT;DigExt)");
