事件定义中为何出现 Lock关键字？
namespace WrapTwoInterfaceEvents{ using System; public interface IDrawingObject { // Raise this event before drawing // the object. event EventHandler OnDraw; } public interface IShape { // Raise this event after drawing // the shape. event EventHandler OnDraw; } // Base class event publisher inherits two // interfaces, each with an OnDraw event public class Shape : IDrawingObject, IShape { // Create an event for each interface event event EventHandler PreDrawEvent; event EventHandler PostDrawEvent; object objectLock = new Object(); // Explicit interface implementation required. // Associate IDrawingObject's event with // PreDrawEvent event EventHandler IDrawingObject.OnDraw { add { lock (objectLock) { PreDrawEvent += value; } } remove { lock (objectLock) { PreDrawEvent -= value; } } } // Explicit interface implementation required. // Associate IShape's event with // PostDrawEvent event EventHandler IShape.OnDraw { add { lock (objectLock) { PostDrawEvent += value; } } remove { lock (objectLock) { PostDrawEvent -= value; } } } // For the sake of simplicity this one method // implements both interfaces. public void Draw() { // Raise IDrawingObject's event before the object is drawn. EventHandler handler = PreDrawEvent; if (handler != null) { handler(this, new EventArgs()); } Console.WriteLine("Drawing a shape."); // RaiseIShape's event after the object is drawn. handler = PostDrawEvent; if (handler != null) { handler(this, new EventArgs()); } } } public class Subscriber1 { // References the shape object as an IDrawingObject public Subscriber1(Shape shape) { IDrawingObject d = (IDrawingObject)shape; d.OnDraw += new EventHandler(d_OnDraw); } void d_OnDraw(object sender, EventArgs e) { Console.WriteLine("Sub1 receives the IDrawingObject event."); } } // References the shape object as an IShape public class Subscriber2 { public Subscriber2(Shape shape) { IShape d = (IShape)shape; d.OnDraw += new EventHandler(d_OnDraw); } void d_OnDraw(object sender, EventArgs e) { Console.WriteLine("Sub2 receives the IShape event."); } } public class Program { static void Main(string[] args) { Shape shape = new Shape(); Subscriber1 sub = new Subscriber1(shape); Subscriber2 sub2 = new Subscriber2(shape); shape.Draw(); // Keep the console window open in debug mode. System.Console.WriteLine("Press any key to exit."); System.Console.ReadKey(); } }}/* Output: Sub1 receives the IDrawingObject event. Drawing a shape. Sub2 receives the IShape event.*/object objectLock = new Object(); // Explicit interface implementation required. // Associate IDrawingObject's event with // PreDrawEvent event EventHandler IDrawingObject.OnDraw { add { lock (objectLock) { PreDrawEvent += value; } } remove { lock (objectLock) { PreDrawEvent -= value; } } }
interface myin { event mylele myevent; }class zi : fu,myin { //event mylele shijian //{ // add { this.myevfu += value; } // remove { this.myevfu -= value; } //} event mylele _mye; event mylele myin.myevent { add { //ock (objectLock) //{ _mye += value; //} } remove { _mye -= value; } } public void shuohua() { Console.WriteLine("shuohua:"); if(_mye!=null) { _mye(this); } } }