外观模式（Facade），为子系统中的一组接口提供一个一致的界面，此模式定义了一个高层接口，这个接口使得这一子系统更加容易使用。
子系统：
package cn.happy.design_pattern._08facade;
public class SubSystemOne {
public void MethodOne(){
System.out.println("子系统方法一");
}
}
public class SubSystemTwo {
public void MethodTwo(){
System.out.println("子系统方法二");
}
}
public class SubSystemThree {
public void MethodTree(){
System.out.println("子系统方法三");
}
}
public class SubSystemFour {
public void MethodFour(){
System.out.println("子系统方法四");
}
}
外观类：
package cn.happy.design_pattern._08facade;
public class Facade {
SubSystemOne one;
SubSystemTwo two;
SubSystemThree three;
SubSystemFour four;
public Facade() {
one = new SubSystemOne();
two = new SubSystemTwo();
three = new SubSystemThree();
four = new SubSystemFour();
}
public void MethodA(){
System.out.println("方法组A:");
one.MethodOne();
two.MethodTwo();
four.MethodFour();
}
public void MethodB(){
System.out.println("方法组B:");
two.MethodTwo();
three.MethodTree();
}
}
测试类：
package cn.happy.design_pattern._08facade;
public class Client {
public static void main(String[] args) {
Facade facade = new Facade();
facade.MethodA();
facade.MethodB();
}
}