声明对象

using System;
using System.ComponentModel;
using System.Reflection;

[Description("用户")]
public class User
{
    [Description("编号")]
    public int Id { get; set; }
    [Description("姓名")]
    public string Name { get; set; }
    [Description("生日")]
    public DateTime BirthDay { get; set; } = DateTime.Now;
}

遍历获取对象

var u = new User();
PropertyInfo[] propertiesInfos= u.GetType().GetProperties();
foreach (var pi in propertiesInfos)
{
    var name = pi.Name;//获取属性名
    var val = pi.GetValue(u);//获取属性值
    var prType = pi.PropertyType;//获取属性类型
    var type = string.Empty;
    if (prType == typeof(string))
        type = "字符串";
    else if (prType == typeof(DateTime))
        type = "日期";
    else if (prType == typeof(int))
        type = "整型";

    var descAttr = Attribute.GetCustomAttribute(pi, typeof(DescriptionAttribute)) as DescriptionAttribute;
    string desc=string.Empty;
    if(descAttr!=null)
        desc = descAttr.Description;// //获取属性Description attribute
    if (val is null)
    {
        pi.SetValue(u, "test");//给属性赋值
        val = pi.GetValue(u);
    }
    Console.WriteLine($"属性名：{name}，属性值：{val}，类型：{type}，属性描述：{desc}");
}

声明自定义Attribute

public sealed class CustomAttribute : Attribute
{
    private readonly string _custom;
    public string Custom
    {
        get { return _custom; }
    }
    public CustomAttribute(string custome)
    {
        _custom = custome;
    }
}

使用自定义Attribute

[Description("用户")]
[Custom("自定义用户")]
public class User
{
    [Description("编号")]
    [Custom("自定义ID")]
    public int Id { get; set; }
    [Description("姓名")]
    public string Name { get; set; }
    [Description("生日")]
    public DateTime BirthDay { get; set; } = DateTime.Now;
}

创建静态扩展类

using System;
using System.Collections.Concurrent;
using System.Reflection;

public static class CustomAttributeExtensions
{
    /// <summary>
    /// Cache Data
    /// </summary>
    private static readonly ConcurrentDictionary<string, object> Cache = new ConcurrentDictionary<string, object>();

    /// <summary>
    /// 获取CustomAttribute Value
    /// </summary>
    /// <typeparam name="TAttribute">Attribute的子类型</typeparam>
    /// <typeparam name="TReturn">TReturn的子类型</typeparam>
    /// <param name="sourceType">头部标有CustomAttribute类的类型</param>
    /// <param name="attributeValueAction">取Attribute具体哪个属性值的匿名函数</param>
    /// <returns>返回Attribute的值，没有则返回null</returns>
    public static TReturn GetCustomAttributeValue<TAttribute, TReturn>(this Type sourceType, Func<TAttribute, TReturn> attributeValueAction)
        where TAttribute : Attribute
    {
        return _getAttributeValue(sourceType, attributeValueAction, null);
    }

    /// <summary>
    /// 获取CustomAttribute Value
    /// </summary>
    /// <typeparam name="TAttribute">Attribute的子类型</typeparam>
    /// <typeparam name="TReturn">TReturn的子类型</typeparam>
    /// <param name="sourceType">头部标有CustomAttribute类的类型</param>
    /// <param name="attributeValueAction">取Attribute具体哪个属性值的匿名函数</param>
    /// <param name="propertyName">field name或property name</param>
    /// <returns>返回Attribute的值，没有则返回null</returns>
    public static TReturn GetCustomAttributeValue<TAttribute, TReturn>(this Type sourceType, Func<TAttribute, TReturn> attributeValueAction, string propertyName)
        where TAttribute : Attribute
    {
        return _getAttributeValue(sourceType, attributeValueAction, propertyName);
    }

    #region private methods

    private static TReturn _getAttributeValue<TAttribute, TReturn>(Type sourceType, Func<TAttribute, TReturn> attributeFunc, string propertyName)
        where TAttribute : Attribute
    {
        var cacheKey = BuildKey<TAttribute>(sourceType, propertyName);
        var value = Cache.GetOrAdd(cacheKey, k => GetValue(sourceType, attributeFunc, propertyName));
        if (value is TReturn) return (TReturn)Cache[cacheKey];
        return default(TReturn);
    }

    private static string BuildKey<TAttribute>(Type type, string propertyName) where TAttribute : Attribute
    {
        var attributeName = typeof(TAttribute).FullName;
        if (string.IsNullOrEmpty(propertyName))
        {
            return type.FullName + "." + attributeName;
        }

        return type.FullName + "." + propertyName + "." + attributeName;
    }

    private static TReturn GetValue<TAttribute, TReturn>(this Type type, Func<TAttribute, TReturn> attributeValueAction, string name)
        where TAttribute : Attribute
    {
        TAttribute attribute = default(TAttribute);
        if (string.IsNullOrEmpty(name))
        {
            attribute = type.GetCustomAttribute<TAttribute>(false);
        }
        else
        {
            var propertyInfo = type.GetProperty(name);
            if (propertyInfo != null)
            {
                attribute = propertyInfo.GetCustomAttribute<TAttribute>(false);
            }
            else
            {
                var fieldInfo = type.GetField(name);
                if (fieldInfo != null)
                {
                    attribute = fieldInfo.GetCustomAttribute<TAttribute>(false);
                }
            }
        }

        return attribute == null ? default(TReturn) : attributeValueAction(attribute);
    }

    #endregion
}

调用扩展方法

//获取类名
var className = typeof(User).GetCustomAttributeValue<CustomAttribute, string>(x => x.Custom);

//获取属性中的自定义Attribute
var customAttrVal = typeof(User).GetCustomAttributeValue<CustomAttribute, string>(x => x.Custom, "Id");

//获取内置的Description Attribute
var descVal = typeof(User).GetCustomAttributeValue<DescriptionAttribute, string>(x => x.Description);

更新于：2015年5月11日

C#