///
    /// Form1
    ///
    ///
    public delegate void ClickDelegateHander(string message); //声明一个委托
    public partial class Form1 : Form
    {
        public event ClickDelegateHander ClickEvent;//声明一个事件
        public Form1()
        {
            InitializeComponent();
        }
        private void button1_Click(object sender, EventArgs e)
        {
            if (ClickEvent != null) //判断事件是否被注册
                ClickEvent("Hello World");
        }
    }

///
   /// Form2
   ///
    public partial class Form2 : Form
    {
        public Form2()
        {
             InitializeComponent();
             Form1 form1 = new Form1();
             form1.ClickEvent += new ClickDelegateHander(getMessage);//注册事件
             form1.Show();
        }
        private void Form2_Load(object sender, EventArgs e)
        {
        }
        public void getMessage(string message)
        {
            this.label1.Text = message;
        }
    }