把Enum与Int32、String的相互转换的代码

平时我们须要把Enum类型与int（或者string）类型进行相互转换，利用下面的泛型编程，可以处理所有情况了。

public static class EnumHelper2<T>
{
    public static String Enum2String(T value)
    {
        return value.ToString();
    }

    public static T String2Enum(string value, bool ignoreCase)
    {
        return (T)Enum.Parse(typeof(T), value, ignoreCase);
    }

    public static int Enum2Int(T value)
    {
        return Convert.ToInt32(value);
    }

    public static T Int2Enum(int value)
    {
        if (Enum.IsDefined(typeof(T), value))
            return (T)Enum.ToObject(typeof(T), value);
        else
            throw new Exception(value + " is not defined");
    }
}

public static class EnumHelper
{
    public static int ToInt32<T>(T value)
    {
        return Convert.ToInt32(value);
    }

    public static T FromInt32<T>(int value)
    {
        return (T)Enum.ToObject(typeof(T), value);
    }

    public static T Parse<T>(string value, bool ignoreCase)
    {
        if (Enum.IsDefined(typeof(T), value))
            return (T)Enum.Parse(typeof(T), value, ignoreCase);
        else
            throw new Exception(value + " is not defined");
    }

    public static T Parse<T>(int value)
    {
        if (Enum.IsDefined(typeof(T), value))
            return (T)Enum.ToObject(typeof(T), value);
        else
            throw new Exception(value + " is not defined");
    }
}