根据类拼凑成url参数
/// <summary>
/// 根据类拼凑成url参数
/// </summary>
/// <typeparam name="T">类</typeparam>
/// <param name="obj"></param>
/// <param name="firstStr">第一个字符 ?或者& </param>
/// <returns>如: ?action=get&data=123</returns>
public static string GetUrlParas<T>(T obj, string firstStr = "?") where T : class //限制为类
{
return obj.GetType().GetProperties().Aggregate(firstStr, (current, p) => current + string.Format("{0}={1}&", p.Name, p.GetValue(obj, null) ?? "")).Trim('&');
}