如何POST一个JSON格式的数据给Restful服务

在Android/java平台上实现POST一个json数据：
JSONObject jsonObj = new JSONObject();
jsonObj.put("username", username);
jsonObj.put("apikey", apikey);
// Create the POST object and add the parameters
HttpPost httpPost = new HttpPost(url);
StringEntity entity = new StringEntity(jsonObj.toString(), HTTP.UTF_8);
entity.setContentType("application/json");
httpPost.setEntity(entity);
HttpClient client = new DefaultHttpClient();
HttpResponse response = client.execute(httpPost);

用curl可执行如下命令：
curl -l -H "Content-type: application/json" -X POST -d '{"phone":"13521389587","password":"test"}' http://domain/apis/users.json

用jQuery：
$.ajax({
  url:url,
  type:"POST",
  data:data,
  contentType:"application/json; charset=utf-8",
  dataType:"json",
  success: function(){
    ...
  }
})