从表单为实体对象赋值

首先需要把从表单获得的字符串转换为指定类型，可以使用以下代码：

object value = Convert.ChangeType(valueStr, desiredType);
// 把valueStr转换为desiredType指定的类型

注意：Convert.ChangeType不能转换Nullable<Type>类型的值。需要进行处理以下函数来转换：

1. 方式一，使用泛型
		public static T ChangeType<T>(object value)
		{
			Type conversionType = typeof(T);

			if (conversionType.IsGenericType 
				&& conversionType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
			{
				if (value == null) 
				{ 
					return default(T); 
				}

				conversionType = Nullable.GetUnderlyingType(conversionType);
			}

			return (T)Convert.ChangeType(value, conversionType);

		}

2. 方式二
		public static object ChangeType(object value, Type conversionType)
		{
			// Note: This if block was taken from Convert.ChangeType as is, and is needed here since we're
			// checking properties on conversionType below.
			if (conversionType == null)
			{
				throw new ArgumentNullException("conversionType");
			} // end if

			// If it's not a nullable type, just pass through the parameters to Convert.ChangeType

			if (conversionType.IsGenericType 
				&& conversionType.GetGenericTypeDefinition().Equals(typeof(Nullable<>)))
			{
				// It's a nullable type, so instead of calling Convert.ChangeType directly which would throw a
				// InvalidCastException (per http://weblogs.asp.net/pjohnson/archive/2006/02/07/437631.aspx),
				// determine what the underlying type is
				// If it's null, it won't convert to the underlying type, but that's fine since nulls don't really
				// have a type--so just return null
				// Note: We only do this check if we're converting to a nullable type, since doing it outside
				// would diverge from Convert.ChangeType's behavior, which throws an InvalidCastException if
				// value is null and conversionType is a value type.
				if (value == null)
				{
					return null;
				} // end if

				// It's a nullable type, and not null, so that means it can be converted to its underlying type,
				// so overwrite the passed-in conversion type with this underlying type
				System.ComponentModel.NullableConverter nullableConverter = new System.ComponentModel.NullableConverter(conversionType);

				conversionType = nullableConverter.UnderlyingType;
			} // end if

			// Now that we've guaranteed conversionType is something Convert.ChangeType can handle (i.e. not a
			// nullable type), pass the call on to Convert.ChangeType
			return Convert.ChangeType(value, conversionType);
		}

通过反射可以获得对象的所有属性以及类型，遍历所有属性调用上面的函数为对象赋值。

public static void GetPost<T>(ref T t)
			{
				System.Collections.Specialized.NameValueCollection form = HttpContext.Current.Request.Form;

				Type type = t.GetType();//获取类型
				PropertyInfo[] pi = type.GetProperties();//获取属性集合
				foreach (PropertyInfo p in pi)
				{
					if (form[p.Name] != null)
					{
						try
						{
							p.SetValue(t, ChangeType(form[p.Name], p.PropertyType), null);//为属性赋值，并转换键值的类型为该属性的类型
						}
						catch
						{
						}
					}
				}
			}