Java 设计模式之：工厂模式( Factory)

Factory.java

 

package com.youngmaster.Factory;

/*类型：工厂模式 
*目的：把创建实例的责任和使用实例的责任分开 
*描述：有个类的一个方法methodA()专门负责生成对象的实例，其他类调用此方法生成一个类的实例 
**/

public class Factory {
	
	public static Shape getInstance(String className){
		
		if(className.equalsIgnoreCase("Square")){
			
			return new Square();
		}
		
		if(className.equalsIgnoreCase("Circle")){
			
			return new Circle();
		}
		return null;
	
	}

}

 

 Shape.java

 

package com.youngmaster.Factory;

public interface Shape {
	
	public int area(int i);
	
	public String toString();

}

 

Square.java

 

package com.youngmaster.Factory;

public class Square implements Shape {

	@Override
	public int area(int i) {

		return i*i;
	}
	
	public String toString(){
		return null;};

}

 

Circle.java

 

package com.youngmaster.Factory;

public class Circle implements Shape {

	@Override
	public int area(int i) {
		
		return (int) (Math.PI*i*i);
	}

}

 

Test.java

 

package com.youngmaster.Factory;

public class Test {

	public static void main(String[] args) {
		
		Shape shape = Factory.getInstance("Square");
		
		System.out.println(shape.area(5));
	}

}