一个C#类型转换类

using System;

namespace Xyz.Util
{
    /// <summary>
    /// 包含类型转换相关的方法。
    /// </summary>
    public static class ConvertUtils
    {
        /// <summary>
        /// 将指定的可转换值转换为指定类型。
        /// </summary>
        /// <param name="input">可转换值。</param>
        /// <param name="toType">目标类型。</param>
        /// <returns>若输入值可转换为目标类型，返回转换后的值；否则返回原输入值。</returns>
        public static object Convert(IConvertible input, Type toType)
        {
            if (toType == typeof(bool))
                return input.ToBoolean(null);

            if (toType == typeof(byte))
                return input.ToByte(null);

            if (toType == typeof(short))
                return input.ToInt16(null);

            if (toType == typeof(int))
                return input.ToInt32(null);

            if (toType == typeof(long))

                return input.ToInt64(null);

            if (toType == typeof(float))
                return input.ToSingle(null);

            if (toType == typeof(double))
                return input.ToDouble(null);

            if (toType == typeof(decimal))
                return input.ToDecimal(null);

            if (toType == typeof(DateTime))
                return input.ToDateTime(null);

            return input;
        }
        public static string ToString(object value)
        {
            if (value == null)
                return "";
            return System.Convert.ToString(value);
        }
        /// <summary>
        /// 将字符串转换成<see cref="double"/>，若值无法被转换，返回<paramref name="defaultValue"/>的值。
        /// </summary>
        /// <param name="value">字符串。</param>
        /// <param name="defaultValue">转换失败时返回的默认值。</param>
        /// <returns><see cref="double"/>值。若值无法被转换，返回<paramref name="defaultValue"/>的值。</returns>
        public static double ToDouble(string value, double defaultValue)
        {