龙的传人

as3实现接口的示例

　　as3实现接口的示例：本范例中先定义了一个名为IGeometricShape的接口，然后在Circle类中实现接口中的getArea和describe两个方法，Circle类中的getCircumference方法是为实现descrebe方法服务的。

接口IgeometricShape中的代码：

package{
public interface IGeometricShape{
function getArea():Number;
function describe():String;
}
}
Circle类中的代码：

package {
public class Circle implements IGeometricShape {
public var diameter:Number;

public function Circle(diam:Number=100) {
this.diameter=diam;
}
public function getArea():Number {
var radius:Number=diameter/2;
return Math.PI * radius * radius;
}
public function getCircumference():Number {
return Math.PI * diameter;
}
public function describe():String {
var desc:String="This shape is a circle.\n";
desc+="Its diameter is "+diameter+" pixels.\n";
desc+="Its area is "+getArea()+".\n";
desc+="Its circumference is "+getCircumference()+".\n";
return desc;
}
}
}
fla文件时间轴上的代码：

var circle=new Circle();
trace(circle.describe());

输出面板中的显示：

This shape is a circle.
Its diameter is 100 pixels.
Its area is 7853.981633974483.
Its circumference is 314.1592653589793.