Enum操作技巧
示例：
VB:
Enum Colors
Red
Green
Blue
Yellow
End Enum
C#：
enum class Colors{ Red, Green, Blue, Yellow};
1.得到枚举中常数值的数组。
VB：
For Each i In [Enum].GetValues(GetType(Coors))
Console.WriteLine(i)
Next i
C#:
for each(int i in Enum.GetValues(typeof(Colors)))
Console.WriteLine(i);
2. 检索指定枚举中常数名称的数组
VB:
For Each s In [Enum].GetNames(GetType(Colors))
Console.WriteLine(s)
Next s
C#：
for each(string s in Enum.GetNames(typeof(Colors)))
Console.WriteLine(s);
3．转换Integer常数值和转换一个String常数名到Eumn实例
VB：
Public Function GetCoorsInstance(ByVal value As String) As Colors
Dim returnValue As Colors = CType([Enum].Parse(GetType(Colors), value), Colors)
Return returnValue
End Function
C#:
public Colors GetCoorsInstance(string value){
Colors returnValue = (Colors)Enum.Parse(typeof(Colors), value);
return returnValue;
}
写一个通用的。
VB：
Public Function GetEnumInstance(Of T)(ByVal enumType As T, ByVal value As String) As T
Dim returnValue As T = CType([Enum].Parse(GetType(T), value), T)
Return returnValue
End Function
C#
public T GetEnumInstance<T>(T enumType, string value){
T returnValue = (T)Enum.Parse(typeof(T), value);
return returnValue;
}
4.结合Attribute的到附加属性
Attribute类将预定义的系统信息或用户定义的自定义信息与目标元素相关联。创建一个继承自Attribute的类
VB：
Public Class StringValueAttribute
Inherits Attribute
Private _StringValue As String
Public Property StringValue() As String
Get
Return _StringValue
End Get
Protected Set(ByVal value As String)
_StringValue = value
End Set
End Property
Public Sub New(ByVal value As String)
Me.StringValue = value
End Sub
End Class
C#:
public class StringValueAttribute : Attribute
{
private string _StringValue;
public string StringValue {
get { return _StringValue; }
protected set { _StringValue = value; }
}
public StringValueAttribute(string value)
{
this.StringValue = value;
}
}
使用.NET3.5的新特性写一个针对Enum的扩展方法（添加System.Reflection引用）,如果不是.NET3.5你可以写成一个函数，只不过调用的时候没有写成扩展来的方便
VB：
<System.Runtime.CompilerServices.Extension()> _
Module EnumHelper
<System.Runtime.CompilerServices.Extension()> _
Public Function GetStringValue(ByVal value As [Enum]) As String
' Get the type
Dim type As Type = value.[GetType]()
' Get fieldinfo for this type
Dim fieldInfo As FieldInfo = type.GetField(value.ToString())
' Get the stringvalue attributes
Dim attribs As StringValueAttribute() = TryCast(fieldInfo.GetCustomAttributes(GetType(StringValueAttribute), False), StringValueAttribute())
' Return the first if there was a match.
Return IIf(attribs.Length > 0, attribs(0).StringValue, Nothing)
End Function
End Module
C#：
[System.Runtime.CompilerServices.Extension()]
Class EnumHelper
{
[System.Runtime.CompilerServices.Extension()]
public string GetStringValue(Enum value)
{
// Get the type
Type type = value.GetType();
// Get fieldinfo for this type
FieldInfo fieldInfo = type.GetField(value.ToString());
// Get the stringvalue attributes
StringValueAttribute[] attribs = fieldInfo.GetCustomAttributes(typeof(StringValueAttribute), false) as StringValueAttribute[];
// Return the first if there was a match.
return (attribs.Length > 0 ? attribs(0).StringValue : null);
}
}
调用，定义你自己的Enum，并且在上面设置StringValueAttribute
定义一个U.S.P.S(美国邮政)的包裹Size
VB：
Public Enum Size
<StringValue("Package length plus girth must equal 84 inches or less")> _
Regular
<StringValue("Parcels that weigh less than 15 pounds but measure more than 84 inches but less than 108 inchess")> _
Large
<StringValue("Parcel Post packages that measure more than 108 inches but not more than 130 inches")> _
Oversize
End Enum
C#：
Public Enum Size
{
[StringValue("Package length plus girth must equal 84 inches or less")]
Regular,
[StringValue("Parcels that weigh less than 15 pounds but measure more than 84 inches but less than 108 inchess")]
Large,
[StringValue("Parcel Post packages that measure more than 108 inches but not more than 130 inches")]
Oversize
}
在程序中使用
VB：
Dim largeSize As Size = Size.Large
Dim value As String = largeSize.GetStringValue
C#：
Size largeSize = Size.Large;
string value = largeSize.GetStringValue
或者直接在Enum类型上使用
Size.Large.GetStringValue()