我有一个类，叫它Book，它的属性叫Name。有了这个属性，我就有了一个与之关联的属性。
public class Book
{
[Author("AuthorName")]
public string Name
{
get; private set;
}
}
在我的主要方法中，我使用反射，并希望获得每个属性的每个属性的键值对。因此，在本例中，我希望看到属性名为“Author”，属性值为“AuthorName”。
问:如何使用反射获取属性上的属性名和值?
当前回答
private static Dictionary<string, string> GetAuthors()
{
return typeof(Book).GetProperties()
.SelectMany(prop => prop.GetCustomAttributes())
.OfType<AuthorAttribute>()
.ToDictionary(a => a.GetType().Name.Replace("Attribute", ""), a => a.Name);
}
使用泛型的示例(目标框架4.5)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
private static Dictionary<string, string> GetAttribute<TAttribute, TType>(
Func<TAttribute, string> valueFunc)
where TAttribute : Attribute
{
return typeof(TType).GetProperties()
.SelectMany(p => p.GetCustomAttributes())
.OfType<TAttribute>()
.ToDictionary(a => a.GetType().Name.Replace("Attribute", ""), valueFunc);
}
使用
var dictionary = GetAttribute<AuthorAttribute, Book>(a => a.Name);
其他回答
如果你的意思是“对于带有一个参数的属性，列出属性名称和参数值”，那么在。net 4.5中通过CustomAttributeData API会更容易:
using System.Collections.Generic;
using System.ComponentModel;
using System.Reflection;
public static class Program
{
static void Main()
{
PropertyInfo prop = typeof(Foo).GetProperty("Bar");
var vals = GetPropertyAttributes(prop);
// has: DisplayName = "abc", Browsable = false
}
public static Dictionary<string, object> GetPropertyAttributes(PropertyInfo property)
{
Dictionary<string, object> attribs = new Dictionary<string, object>();
// look for attributes that takes one constructor argument
foreach (CustomAttributeData attribData in property.GetCustomAttributesData())
{
if(attribData.ConstructorArguments.Count == 1)
{
string typeName = attribData.Constructor.DeclaringType.Name;
if (typeName.EndsWith("Attribute")) typeName = typeName.Substring(0, typeName.Length - 9);
attribs[typeName] = attribData.ConstructorArguments[0].Value;
}
}
return attribs;
}
}
class Foo
{
[DisplayName("abc")]
[Browsable(false)]
public string Bar { get; set; }
}
从enum中获取属性，我使用:
public enum ExceptionCodes
{
[ExceptionCode(1000)]
InternalError,
}
public static (int code, string message) Translate(ExceptionCodes code)
{
return code.GetType()
.GetField(Enum.GetName(typeof(ExceptionCodes), code))
.GetCustomAttributes(false).Where((attr) =>
{
return (attr is ExceptionCodeAttribute);
}).Select(customAttr =>
{
var attr = (customAttr as ExceptionCodeAttribute);
return (attr.Code, attr.FriendlyMessage);
}).FirstOrDefault();
}
/ /使用
var _message = Translate(code);
Necromancing。 对于那些仍然需要维护。net 2.0的人，或者那些不想使用LINQ的人:
public static object GetAttribute(System.Reflection.MemberInfo mi, System.Type t)
{
object[] objs = mi.GetCustomAttributes(t, true);
if (objs == null || objs.Length < 1)
return null;
return objs[0];
}
public static T GetAttribute<T>(System.Reflection.MemberInfo mi)
{
return (T)GetAttribute(mi, typeof(T));
}
public delegate TResult GetValue_t<in T, out TResult>(T arg1);
public static TValue GetAttributValue<TAttribute, TValue>(System.Reflection.MemberInfo mi, GetValue_t<TAttribute, TValue> value) where TAttribute : System.Attribute
{
TAttribute[] objAtts = (TAttribute[])mi.GetCustomAttributes(typeof(TAttribute), true);
TAttribute att = (objAtts == null || objAtts.Length < 1) ? default(TAttribute) : objAtts[0];
// TAttribute att = (TAttribute)GetAttribute(mi, typeof(TAttribute));
if (att != null)
{
return value(att);
}
return default(TValue);
}
使用示例:
System.Reflection.FieldInfo fi = t.GetField("PrintBackground");
wkHtmlOptionNameAttribute att = GetAttribute<wkHtmlOptionNameAttribute>(fi);
string name = GetAttributValue<wkHtmlOptionNameAttribute, string>(fi, delegate(wkHtmlOptionNameAttribute a){ return a.Name;});
或者简单地
string aname = GetAttributValue<wkHtmlOptionNameAttribute, string>(fi, a => a.Name );
private static Dictionary<string, string> GetAuthors()
{
return typeof(Book).GetProperties()
.SelectMany(prop => prop.GetCustomAttributes())
.OfType<AuthorAttribute>()
.ToDictionary(a => a.GetType().Name.Replace("Attribute", ""), a => a.Name);
}
使用泛型的示例(目标框架4.5)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
private static Dictionary<string, string> GetAttribute<TAttribute, TType>(
Func<TAttribute, string> valueFunc)
where TAttribute : Attribute
{
return typeof(TType).GetProperties()
.SelectMany(p => p.GetCustomAttributes())
.OfType<TAttribute>()
.ToDictionary(a => a.GetType().Name.Replace("Attribute", ""), valueFunc);
}
使用
var dictionary = GetAttribute<AuthorAttribute, Book>(a => a.Name);
你可以使用GetCustomAttributesData()和GetCustomAttributes():
var attributeData = typeof(Book).GetProperty("Name").GetCustomAttributesData();
var attributes = typeof(Book).GetProperty("Name").GetCustomAttributes(false);
