targetはAndroid2.3.4、API 10向けにビルドして試した。
参考:
<uses-permission android:name="android.permission.INTERNET" />
import java.io.*;
import java.util.*;
import org.apache.http.*;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
HttpClient client = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://localhost:8080");
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("message", "ほむ"));
try{
    httppost.setEntity(new UrlEncodedFormEntity(params, "UTF-8"));
    HttpResponse res = client.execute(httppost);
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    res.getEntity().writeTo(os);
    Log.v("result", os.toString());
    Log.v("status", res.getStatusLine().getStatusCode());
}
catch(Exception e){
    e.printStackTrace();
}
リクエストができているかの確認は、EM::HttpServerで見た
gem install eventmachine_httpserver
#!/usr/bin/env ruby
require 'rubygems'
require 'eventmachine'
require 'evma_httpserver'
class Handler  < EM::Connection
  include EM::HttpServer
 
  def process_http_request
    res = EM::DelegatedHttpResponse.new(self)
    puts "request_method : #{@http_request_method}"
    puts "path_info : #{@http_path_info}"
    puts "query_str : #{@http_query_string}"
    puts "post_content : #{@http_post_content}"
    res.status = 200
    res.content = "こんにちは"
    res.send_response
  end
end
EM::run do
  EM::start_server("0.0.0.0", 8080, Handler)
  puts "http server start, prot 8080"
end