C#中方括号是什么意思

Question

using System;
using System.ComponentModel;
using System.Security.Permissions;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;namespace Samples.AspNet.CS.Controls
{
    [
    AspNetHostingPermission(SecurityAction.Demand,
        Level = AspNetHostingPermissionLevel.Minimal),
    AspNetHostingPermission(SecurityAction.InheritanceDemand, 
        Level=AspNetHostingPermissionLevel.Minimal),
    DefaultProperty("Text"),
    ToolboxData("<{0}:WelcomeLabel runat=\"server\"> </{0}:WelcomeLabel>")
    ]
    public class WelcomeLabel : WebControl
    {
        [
        Bindable(true),
        Category("Appearance"),
        DefaultValue(""),
        Description("The welcome message text."),
        Localizable(true)
        ]
        public virtual string Text
        {
            get
            {
                string s = (string)ViewState["Text"];
                return (s == null) ? String.Empty : s;
            }
            set
            {
                ViewState["Text"] = value;
            }
        }

Answer 1

属性，注意Attribute 与 property的区别

Answer 2

特征using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Reflection; namespace WindowsApplication166
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();            foreach (MethodInfo MI in this.GetType().GetMethods())
                foreach (Attribute A in MI.GetCustomAttributes(false))
                    if (A is XXX)
                        MessageBox.Show("方法 " + MI.Name + " 是XXX特征的");
        }        [AttributeUsage(AttributeTargets.Method)]   
        class XXX : Attribute
        {
        }        [XXX]
        public void A()
        {
        }        public void B()
        {
        }
    }
}