Android HttpPost - 在cp1251中发送请求

Question

我使用以下代码发送请求：

final DefaultHttpClient client = new DefaultHttpClient();
List<NameValuePair> pairs = new ArrayList<NameValuePair>();
pairs.add(new BasicNameValuePair("number", pNumber));
final HttpPost httpPost = new HttpPost(URL_MAIN);
httpPost.setEntity(new UrlEncodedFormEntity(pairs));
client.execute(httpPost);

它以UTF-8发送请求，但我需要cp1251（站点仅适用于此CP）。如何将其编码到cp1251中？