设计模式之装饰器模式
结构
说明
Attach additional responsibilities to an object dynamically keeping the same interface. Decorators provide a flexible alternative to subclassing for extending functionality.
向某个对象动态地添加更多的功能。修饰模式是除类继承外另一种扩展功能的方法。
适用条件
- 在不影响其他对象的情况下， 以动态且透明的方式添加单个对象的功能；
- 处理那些可以撤销的功能；
- 不能采用生成子类的方法扩充时；
实现
代码语言：javascript复制interface IWindow {
void Draw();
string GetDescription();
}
class SimpleWindow : IWindow {
public void Draw() {
//
}
public string GetDescription() {
return "Simple window";
}
}
class WindowDecorator : IWindow {
protected IWindow DecoratedWindow;
public WindowDecorator(IWindow decoratedWindow) {
this.DecoratedWindow = decoratedWindow;
}
public virtual void Draw() {
this.DecoratedWindow.Draw();
}
public virtual string GetDescription() {
return "Window decorator";
}
}
class VerticalScrollbarWindow : WindowDecorator {
public VerticalScrollbarWindow(IWindow decoratedWindow) : base( decoratedWindow) {
}
public override void Draw() {
base.Draw();
this.DrawVerticalScrollbar();
}
private void DrawVerticalScrollbar() {
//
}
public override string GetDescription() {
return this.DecoratedWindow.GetDescription() ", include vertical scrollbars";
}
}
class HorizontalScrollbarWindow : WindowDecorator {
public HorizontalScrollbarWindow(IWindow decoratedWindow) : base( decoratedWindow) {
}
public override void Draw() {
base.Draw();
this.DrawHorizontalScrollbar();
}
private void DrawHorizontalScrollbar() {
//
}
public override string GetDescription() {
return this.DecoratedWindow.GetDescription() ", include horizontal scrollbars";
}
}
class Program {
static void Main(string[] args) {
IWindow window = new HorizontalScrollbarWindow(new VerticalScrollbarWindow (new SimpleWindow()));
Console.WriteLine(window.GetDescription());
Console.ReadKey();
}
}
