外观模式(Facade)

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using System;namespace RefactoringGuru.DesignPatterns.Facade.Conceptual{ // The Facade class provides a simple interface to the complex logic of one // or several subsystems. The Facade delegates the client requests to the // appropriate objects within the subsystem. The Facade is also responsible // for managing their lifecycle. All of this shields the client from the // undesired complexity of the subsystem. public class Facade { protected Subsystem1 _subsystem1; protected Subsystem2 _subsystem2; public Facade(Subsystem1 subsystem1, Subsystem2 subsystem2) { this._subsystem1 = subsystem1; this._subsystem2 = subsystem2; } // The Facade's methods are convenient shortcuts to the sophisticated // functionality of the subsystems. However, clients get only to a // fraction of a subsystem's capabilities. public string Operation() { string result = "Facade initializes subsystems:\n"; result += this._subsystem1.operation1(); result += this._subsystem2.operation1(); result += "Facade orders subsystems to perform the action:\n"; result += this._subsystem1.operationN(); result += this._subsystem2.operationZ(); return result; } } // The Subsystem can accept requests either from the facade or client // directly. In any case, to the Subsystem, the Facade is yet another // client, and it's not a part of the Subsystem. public class Subsystem1 { public string operation1() { return "Subsystem1: Ready!\n"; } public string operationN() { return "Subsystem1: Go!\n"; } } // Some facades can work with multiple subsystems at the same time. public class Subsystem2 { public string operation1() { return "Subsystem2: Get ready!\n"; } public string operationZ() { return "Subsystem2: Fire!\n"; } } class Client { // The client code works with complex subsystems through a simple // interface provided by the Facade. When a facade manages the lifecycle // of the subsystem, the client might not even know about the existence // of the subsystem. This approach lets you keep the complexity under // control. public static void ClientCode(Facade facade) { Console.Write(facade.Operation()); } } class Program { static void Main(string[] args) { // The client code may have some of the subsystem's objects already // created. In this case, it might be worthwhile to initialize the // Facade with these objects instead of letting the Facade create // new instances. Subsystem1 subsystem1 = new Subsystem1(); Subsystem2 subsystem2 = new Subsystem2(); Facade facade = new Facade(subsystem1, subsystem2); Client.ClientCode(facade); } }}

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Facade initializes subsystems:Subsystem1: Ready!Subsystem2: Get ready!Facade orders subsystems to perform the action:Subsystem1: Go!Subsystem2: Fire!