Design mode (facade) status (caveats)

Appearance mode (facade), a set of interfaces of a subsystem provides a consistent interface that defines a high-level interface that makes this subsystem easier to use.
The appearance pattern perfectly embodies the principle of dependence reversal, the idea of Dimitri Law, one of the formula.

The appearance pattern structure diagram is as follows:

Define three subsystem classes

 Public classSubsystemone { Public void MethodOne() {System. out. println ("Subsystem Method 1"); }} Public classSubsystemtwo { Public void Methodtwo() {System. out. println ("Subsystem Method 2"); }} Public classSubsystemthree { Public void Methodthree() {System. out. println ("Subsystem Method 3"); }}

Define a skin facade class

public      Class  facade {private  subsystemone one; private     Subsystemtwo; private     Subsystemthree three; public  facade         () {One =new  subsystemone ();        Two=new  subsystemtwo ();    Three=new  subsystemthree (); } public  void          MethodA  () {one.methodone ();    Three.methodthree (); } public  void          MethodB  () {one.methodone ();    Two.methodtwo (); }}

Client code

publicstaticvoidmain(String[] args) {        Facade facade=new Facade();        facade.methodA();        facade.methodB();}

Because of the role of the facade class. Client can not know the existence of three subsystems at all

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Design mode (facade) status (caveats)