外观模式

1、什么是外观设计模式

外观模式（Facade Pattern）门面模式，隐藏系统的复杂性，并向客户端提供了一个客户端可以访问系统的接口。这种类型的设计模式属于结构型模式，它向现有的系统添加一个接口，来隐藏系统的复杂性。

这种模式涉及到一个单一的类，该类提供了客户端请求的简化方法和对现有系统类方法的委托调用。

2、外观模式例子

（用户注册完之后，需要调用阿里短信接口、邮件接口、微信推送接口。）

//邮件发送
public interface EamilSmsService {
	  public void sendSms();	
}
public class EamilSmsServiceImpl implements   EamilSmsService{
	public void sendSms() {
		System.out.println("发送邮件消息");
		
	}
}

//微信接口
public interface WeiXinSmsService {
  public void sendSms();	
}
public class WeiXinSmsServiceImpl implements   WeiXinSmsService {

	@Override
	public void sendSms() {
		System.out.println("发送邮件消息");
		
	}

}

//阿里短信消息
public interface AliSmsService {
	public void sendSms();
}
public class AliSmsServiceImpl implements AliSmsService {

	@Override
	public void sendSms() {
     System.out.println("支付宝发送消息...");
	}

}

门面类

//门面类
public class Computer {
	AliSmsService aliSmsService;
	EamilSmsService eamilSmsService;
	WeiXinSmsService weiXinSmsService;

	public Computer() {
		aliSmsService = new AliSmsServiceImpl();
		eamilSmsService = new EamilSmsServiceImpl();
		weiXinSmsService = new WeiXinSmsServiceImpl();
	}

	public void sendMsg() {
		aliSmsService.sendSms();
		eamilSmsService.sendSms();
		weiXinSmsService.sendSms();

	}

}

测试类

public class Client {

	public static void main(String[] args) {
		// AliSmsService aliSmsService= new AliSmsServiceImpl();
		// EamilSmsService eamilSmsService= new EamilSmsServiceImpl();
		// WeiXinSmsService weiXinSmsService= new WeiXinSmsServiceImpl();
		// aliSmsService.sendSms();
		// eamilSmsService.sendSms();
		// weiXinSmsService.sendSms();
		new Computer().sendMsg();
	}

}