新建解决方案WindowsFormsApplication1

新建类MyAttribute

using System;

namespace WindowsFormsApplication1
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1710:IdentifiersShouldHaveCorrectSuffix")]
    [AttributeUsage(AttributeTargets.Class, AllowMultiple = true, Inherited = false)]
    public class MyAttribute : Attribute
    {
        private string _value;

        public string Value
        {
            get
            {
                return _value;
            }
        }

        public MyAttribute(string value)
        {
            _value = value;
        }
    }
}

窗体代码

using System;
using System.Reflection;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    [MyAttribute("HEYU5220")]//自定义属性
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Type[] types = Assembly.GetExecutingAssembly().GetTypes();
            foreach (Type t in types)
            {
                object[] attributes = t.GetCustomAttributes(typeof(MyAttribute), true);
                foreach (object obj in attributes)
                {
                    MyAttribute attribute = (MyAttribute)obj;
                    if (!string.IsNullOrEmpty(attribute.Value))
                    {
                        MessageBox.Show(attribute.Value);
                    }
                }
            }
        }
    }
}