private static extern IntPtr nim_http_create_request([MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(NimUtility.Utf8StringMarshaler))] string url,
IntPtr post_body, int post_body_size, NIMHttp.ResponseCb response_cb, IntPtr user_data);
/// <summary>
/// 创建任务
/// </summary>
/// <param name="url">资源地址</param>
/// <param name="post_body">上传内容</param>
/// <param name="post_body_size">上传内容大小</param>
/// <param name="response_cb">结束回调，响应实体内容</param>
/// <param name="user_data">自定义数据</param>
/// <returns>http任务句柄</returns>
public static IntPtr CreateRequest(string url, IntPtr post_body, int post_body_size, NIMHttp.ResponseCb response_cb, IntPtr user_data)
{
return(nim_http_create_request(url, post_body, post_body_size, response_cb, user_data));
}