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
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; }
}
其他回答
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);
public static class PropertyInfoExtensions
{
public static TValue GetAttributValue<TAttribute, TValue>(this PropertyInfo prop, Func<TAttribute, TValue> value) where TAttribute : Attribute
{
var att = prop.GetCustomAttributes(
typeof(TAttribute), true
).FirstOrDefault() as TAttribute;
if (att != null)
{
return value(att);
}
return default(TValue);
}
}
用法:
//get class properties with attribute [AuthorAttribute]
var props = typeof(Book).GetProperties().Where(prop => Attribute.IsDefined(prop, typeof(AuthorAttribute)));
foreach (var prop in props)
{
string value = prop.GetAttributValue((AuthorAttribute a) => a.Name);
}
or:
//get class properties with attribute [AuthorAttribute]
var props = typeof(Book).GetProperties().Where(prop => Attribute.IsDefined(prop, typeof(AuthorAttribute)));
IList<string> values = props.Select(prop => prop.GetAttributValue((AuthorAttribute a) => a.Name)).Where(attr => attr != null).ToList();
我已经通过编写一个通用扩展属性属性助手解决了类似的问题:
using System;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
public static class AttributeHelper
{
public static TValue GetPropertyAttributeValue<T, TOut, TAttribute, TValue>(
Expression<Func<T, TOut>> propertyExpression,
Func<TAttribute, TValue> valueSelector)
where TAttribute : Attribute
{
var expression = (MemberExpression) propertyExpression.Body;
var propertyInfo = (PropertyInfo) expression.Member;
var attr = propertyInfo.GetCustomAttributes(typeof(TAttribute), true).FirstOrDefault() as TAttribute;
return attr != null ? valueSelector(attr) : default(TValue);
}
}
用法:
var author = AttributeHelper.GetPropertyAttributeValue<Book, string, AuthorAttribute, string>(prop => prop.Name, attr => attr.Author);
// author = "AuthorName"
如果你想获得具有自定义属性的属性，那么请尝试以下方法:
IEnumerable propertyInfos = properties.GetType().GetProperties();
PropertyInfo p = PropertyInfo。Where(x => x. getcustomattribute () != null);
如果你只想要一个特定的属性值，例如Display Attribute，你可以使用以下代码:
var pInfo = typeof(Book).GetProperty("Name")
.GetCustomAttribute<DisplayAttribute>();
var name = pInfo.Name;
