[design pattern] [java] Facade Pattern

我認為wiki寫的蠻清楚的，這邊直接貼上說明

A facade is an object that provides a simplified interface to a larger body of code, such as a class library. A facade can:

• make a software library easier to use, understand and test, since the facade has convenient methods for common tasks;
• make the library more readable, for the same reason;
• reduce dependencies of outside code on the inner workings of a library, since most code uses the facade, thus allowing more flexibility in developing the system;
• wrap a poorly designed collection of APIs with a single well-designed API (as per task needs).

The Facade design pattern is often used when a system is very complex or difficult to understand because the system has a large number of interdependent classes or its source code is unavailable. This pattern hides the complexities of the larger system and provides a simpler interface to the client. It typically involves a single wrapper class which contains a set of members required by client. These members access the system on behalf of the facade client and hide the implementation details.

Animal.java

package com.test.facadepattern;

public interface Animal {

 void printMsg();
 void getFeet();
 void life();
}

Bird.java

package com.test.facadepattern;

public class Bird implements Animal{

 @Override
 public void printMsg() {
  // TODO Auto-generated method stub
  System.out.println("bird class");
 }

 @Override
 public void getFeet() {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void life() {
  // TODO Auto-generated method stub
  
 }
 

}

Cat.java

package com.test.facadepattern;

public class Cat implements Animal {

 @Override
 public void printMsg() {
  // TODO Auto-generated method stub
  System.out.println("cat class");
 }

 @Override
 public void getFeet() {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void life() {
  // TODO Auto-generated method stub
  
 }


 
}

Dog.java

package com.test.facadepattern;

public class Dog implements Animal{

 @Override
 public void printMsg() {
  // TODO Auto-generated method stub
  System.out.println("dog class");
 }

 @Override
 public void getFeet() {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void life() {
  // TODO Auto-generated method stub
  
 }
 


}

Zoo.java

package com.test.facadepattern;

public class Zoo {

 private Animal bird ;
 private Animal cat ;
 private Animal dog ;
 
 public Zoo(){
  bird  = new Bird();
  dog   = new Dog();
  cat   = new Cat();
 }
 
 public void imDog(){
  dog.printMsg();
 }
 
 public void imBird(){
  bird.printMsg();
 }
 
 public void imCat(){
  cat.printMsg();
 }
 
}

testFacadePattern .java

package com.test.facadepattern;

public class testFacadePattern {

 public static void main(String[] args) {
  
  Zoo zoo = new Zoo();
  
  zoo.imBird();
  zoo.imCat();
  zoo.imDog();
  
 }

}

console

bird class
cat class
dog class