使用httpclient非常简单。这是本教程的链接。

http://hc.apache.org/httpcomponents-client-
ga/tutorial/html/fundamentals.html#d5e43

HttpClient httpclient = new DefaultHttpClient();
HttpGet httpget = new HttpGet(urltofetch);
HttpResponse response = httpclient.execute(httpget);
HttpEntity entity = response.getEntity();
if (entity != null) {
    long len = entity.getContentLength();
    InputStream inputStream = entity.getContent();
    // write the file to whether you want it.
}