[修飾符] interface 接口名 extends 父接口1，父接口2，…{
//常量定義
//方法定義
}
class 類名 extends 父類名 implements 接口1，接口2，…{
//類成員
}

//先定義USB接口，通過service()方法提供服務
/*
 * USB接口
 */
public interface UsbInterFace {
	/*
	 * USB接口提供服務
	 */
	void service();
}

//定義U盤類，實現(xiàn)USB接口中的service()方法，進行數(shù)據(jù)傳輸
/*
 * U盤
 */
public class UDisk implements UsbInterFace{
	public void service(){
		System.out.println("連接USB口，開始傳輸數(shù)據(jù)");
	}

}

//定義USB風扇類，實現(xiàn)USB接口中的service()方法，獲得電流使風扇轉動
/*
 * USB風扇
 */
public class UsbFan implements UsbInterFace{
	public void service(){
		System.out.println("連接USB口,獲得電流，風扇開始轉動");
	}
}
//編寫測試類，實現(xiàn)U盤傳輸數(shù)據(jù)，使USB風扇轉動
/*
 * 測試類
 */
public class Test {

	public static void main(String[] args) {
		//1.U盤
		UsbInterFace uDisk=new UDisk();
		uDisk.service();
		//2.USB風扇
		UsbInterFace usbFan=new UsbFan();
		usbFan.service();
	}
}

//定義Door類，具有開和關的功能
/*
 * 門
 */
public abstract class Door {
	public abstract void open();//開
	public abstract void close();//關
}

//定義Lock接口，具備上鎖和開鎖的功能
/*
 * 鎖，接口
 */
public interface Lock {
	void lockUp();//上鎖
	void openLock();//開鎖
}

//定義TheftproofDoor類，繼承Door類，實現(xiàn)Lock接口
*
 * 防盜門類
 */
public class TheftproofDoor extends Door implements Lock,DoorBell{
	public void lockUp() {
		System.out.println("插進鑰匙，向左旋轉鑰匙三圈，鎖上了，拔出鑰匙");
	}
	public void openLock(){
		System.out.println("插進鑰匙，向右旋轉鑰匙三圈，鎖打開了，拔出鑰匙");
	}
	public void open(){
		System.out.println("用力推，門打開了");
	}
	public void close(){
		System.out.println("輕輕拉門，門關上了");
	}
}

//編寫測試類，實現(xiàn)防盜門的關門，開門，上鎖，開鎖的功能
/*
 * 測試類
 */
public class DoorTest {
	public static void main(String[] args) {
		TheftproofDoor tfd=new TheftproofDoor();
		tfd.close();//關門
		tfd.lockUp();//上鎖
		tfd.takePictures();//來訪客人拍照存儲
		tfd.openLock();//開鎖
		tfd.open();//開門
	}
}

/*
 * 門鈴接口
 */
public interface DoorBell {
	void takePictures();//鈴響拍照存檔功能
}

//為防盜門增加門鈴功能
/*
 * 防盜門類
 */
public class TheftproofDoor extends Door implements Lock,DoorBell{
//省略其他實現(xiàn)方法
public void takePictures(){
		System.out.println("鈴......咔嚓......照片已存儲");
	}
}

//修改測試類，代碼如下：
/*
 * 測試類
 */
public class DoorTest {
	public static void main(String[] args) {
		TheftproofDoor tfd=new TheftproofDoor();
		tfd.close();//關門
		tfd.lockUp();//上鎖
		tfd.takePictures();//來訪客人拍照存儲
		tfd.openLock();//開鎖
		tfd.open();//開門
	}
}

//定義墨盒接口InkBox，約定墨盒有顏色
/*
 * 墨盒接口
 */
public interface InkBox {
	/*
	 * 得到墨盒顏色
	 */
	public String getColor();
}

//定義紙張接口Paper，約定紙張有大小
/*
 * 紙張接口
 */
public interface Paper {
	/*
	 * 得到紙張大小
	 */
	public String getSize();
}

//定義打印機類，引用墨盒接口，紙張接口實現(xiàn)打印功能
/*
 * 打印機類
 */
public class Printer {
	InkBox inkBox;//墨盒
	Paper paper;//紙張
	/*
	 * 設置打印機墨盒
	 */
	public void setInkBox(InkBox inkBox){
		this.inkBox=inkBox;
	}
	/*
	 * 設置打印機紙張
	 */
	public void setPaper(Paper paper){
		this.paper=paper;
	}
	/*
	 * 使用墨盒在紙張上打印
	 */
	public void print(){
		System.out.println("使用"+inkBox.getColor()+"墨盒在"+paper.getSize()+"紙張上打印");
	}
}

//墨盒廠商按照InkBox接口實現(xiàn)ColorInkbox類和GrayInkBox類
/*
 * 彩色墨盒
 */
public class ColorInkBox implements InkBox{
	public String getColor(){
		return "彩色";
	}
}
/*
 * 墨色墨盒
 */

public class GrayInkBox implements InkBox{
	public String getColor(){
		return "黑色";
	}
}
/*
 * 墨色墨盒
 */

public class GrayInkBox implements InkBox{
	public String getColor(){
		return "黑色";
	}
}
/*
 * 墨色墨盒
 */

public class GrayInkBox implements InkBox{
	public String getColor(){
		return "黑色";
	}
}
//紙張廠商按照Paper接口實現(xiàn)A4Paper類和B5Paper類
public class A4Paper implements Paper{
	public String getSize(){
		return "A4";
	}
}
public class B5Paper implements Paper{
	public String getSize(){
		return "B5";
	}

}
//“組裝”打印機，讓打印機通過不同的墨盒和紙張實現(xiàn)打印
public class TestInkBox {
	public static void main(String[] args) {
		//1.定義打印機
		InkBox inkBox=null;
		Paper paper=null;
		Printer printer=new Printer();
		
		//2.使用黑白墨盒在A4紙上打印
		inkBox=new GrayInkBox();
		paper=new A4Paper();
		printer.setInkBox(inkBox);
		printer.setPaper(paper);
		printer.print();
		
		3.使用彩色墨盒在B5紙上打印
		inkBox=new ColorInkBox();
		paper=new B5Paper();
		printer.setInkBox(inkBox);
		printer.setPaper(paper);
		printer.print();
		
		//4.使用彩色墨盒在A4紙上打印
		paper=new A4Paper();
		printer.setPaper(paper);
		printer.print();
	}
}

[修飾符] interface 接口名：父接口1，父接口2，…{
屬性定義
方法定義
}
class 類名：父類名，接口1，接口2，…{}

namespace InterfaceDemo
{
    public interface InkBox
    {
        string Color { get; }
    }
    public interface Paper
    {
        string Size { get; }
    }
    class Printer
    {
        InkBox inkBox;//墨盒
        public InkBox InkBox
        {
            set { inkBox = value; }
        }
        Paper paper;//紙張
        public Paper Paper
        {
            set { paper = value; }
        }
        public void print()
        {
            Console.WriteLine("使用" + inkBox.Color + "墨盒在" + paper.Size + "紙上打印");
        }
    }
    public class ColorInkBox: InkBox
    {
        public string Color { get { return "彩色"; } }
    }
    public class GrayInkBox: InkBox
    {
        public string Color { get { return "黑白"; } }
    }
    public class A4Paper : Paper
    {
        public string Size { get { return "A4"; } }
    }
    public class B5Paper : Paper
    {
        public string Size { get { return "B5"; } }
    }
    public class Program
    {
        static void Main(string[] args)
        {
            InkBox inkBox = null;
            Paper paper = null;
            Printer printer = new Printer();

            inkBox = new GrayInkBox();
            paper = new A4Paper();
            printer.InkBox = inkBox;
            printer.Paper = paper;
            printer.print();

            inkBox = new ColorInkBox();
            paper = new B5Paper();
            printer.InkBox = inkBox;
            printer.Paper = paper;
            printer.print();

            paper = new A4Paper();
            printer.Paper = paper;
            printer.print();
            Console.ReadLine();
        }
    }
}