Javaで認証が必要なProxyサーバー経由でHTTP接続する

URLConnectionを使用する場合

Authenticatorの実装クラスを作成してユーザー名とパスワードを設定する。
少し古い情報だとシステムプロパティのproxyUserとproxyPasswordを使うように書いてあるが、現在は使用できないので注意。

    public static String URL = "http://www.apache.org/";
    public static String HOST = "proxy.server";
    public static int PORT = 9000;
    public static String USER = "user";
    public static String PASSWORD = "pass";

    public static void example1() throws Exception {
        System.setProperty("proxySet", "true");
        System.setProperty("proxyHost", HOST);
        System.setProperty("proxyPort", Integer.toString(PORT));

        Authenticator.setDefault(new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(USER, PASSWORD.toCharArray());
            }
        });

        URL url = new URL(URL);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        System.out.println(conn.getResponseCode());
    }

HttpClient4.3を使用する場合

    public static void example2() throws Exception {
        HttpHost proxy = new HttpHost(HOST, PORT);
        CredentialsProvider credsProvider = new BasicCredentialsProvider();
        credsProvider.setCredentials(
                new AuthScope(proxy),
                new UsernamePasswordCredentials(USER, PASSWORD));
        RequestConfig config = RequestConfig.custom()
                .setProxy(proxy)
                .build();
        HttpClient httpclient = HttpClients.custom()
                .setDefaultCredentialsProvider(credsProvider)
                .setDefaultRequestConfig(config)
                .build();

        HttpGet get = new HttpGet(URL);
        HttpResponse res = httpclient.execute(get);
        System.out.println(res.getStatusLine());
    }

参考

Apache HttpComponents > HttpClient 4.3 > Examples > Proxy authentication