/// <summary>
/// 将字符串转化为指定类型
/// </summary>
/// <typeparam name="T">指定的类型</typeparam>
/// <param name="str">需要转换的字符串</param>
/// <returns></returns>
public static T ChangeTo<T>(string str)
{
T result = default(T);
result = (T)Convert.ChangeType(str, typeof(T)); return result;
}