Java-马士兵设计模式学习笔记-工厂模式-单例及多例

一、单例的作用是用于控制类的生成方式，而不让外部类任意new对象

1.Car.java

import java.util.ArrayList;

import java.util.List;



public class Car {



	//私有化构造函数，防止被外部的类new

	private Car() {

	}



	private static Car car = new Car();						//单例

	private static List<Car> cars = new ArrayList<Car>();	//多例，类似连接池

	

	public static Car getInstance() {

		return car;

	}



	public void run() {

		System.out.println("Car running...............");

	}

	

}

　　

2.Test.java

public class Test {

	

	@org.junit.Test

	public void test() {

		Car car = Car.getInstance();

		car.run();

		Car car2 = Car.getInstance();

		System.out.println(car == car2);

		System.out.println(car.equals(car2));

	}

}

　　

运行结果：