List<NameValuePair> formparams = new ArrayList<NameValuePair>(); // 请求参数 
     for (NameValuePair p : params) { 
       formparams.add(p); 
     } 
     UrlEncodedFormEntity entity = new UrlEncodedFormEntity(formparams,HTTP.UTF_8); 
     // 创建POST请求 
     HttpPost httppost = new HttpPost(url); 
     httppost.setEntity(entity); 

Andorid :content-type:application/x-www-form-urlencoded;
IPHONE:content-type:application/x-www-form-urlencoded; charset=utf-8

httppost.setHeader("Content-Type", "application/x-www-form-urlencoded; charset=utf-8");