线程-设计模式

    设计模式：创建型模式简单工厂模式工厂方法模式单例模式行为型模式结构型模式

简单工厂模式

点击查看代码

public abstract class Animal {public abstract void eat();public abstract void sleep();
}public class Cat extends Animal{@Overridepublic void eat() {System.out.println("猫吃鱼");}@Overridepublic void sleep() {System.out.println("猫蜷着睡");}
}public class Dog extends Animal {@Overridepublic void eat() {System.out.println("狗吃肉");}@Overridepublic void sleep() {System.out.println("狗侧着睡");}
}public class AnimalFactory {private AnimalFactory() {}public static Animal createAnimal(String name){if("dog".equals(name)){return new Dog();}else if("cat".equals(name)){return new Cat();}else {System.out.println("没有该动物");return null;}}
}public class FactoryDemo1 {public static void main(String[] args) {//养一只狗Animal d1 = AnimalFactory.createAnimal("dog");//养一只猫Animal c1 = AnimalFactory.createAnimal("cat");d1.eat();d1.sleep();}
}

工厂方法模式

点击查看代码

public abstract class Animal {public abstract void eat();public abstract void sleep();
}public class Cat extends Animal{@Overridepublic void eat() {System.out.println("猫吃鱼");}@Overridepublic void sleep() {System.out.println("猫蜷着睡");}
}public class Dog extends Animal {@Overridepublic void eat() {System.out.println("狗吃肉");}@Overridepublic void sleep() {System.out.println("狗侧着睡");}
}public abstract class AnimalFactory {public abstract Animal createAnimal();
}public class CatFactory extends AnimalFactory{@Overridepublic Animal createAnimal() {return new Cat();}
}public class DogFactory extends AnimalFactory{@Overridepublic Animal createAnimal() {return new Dog();}
}public class FactoryDemo1 {public static void main(String[] args) {DogFactory dogFactory = new DogFactory();CatFactory catFactory = new CatFactory();//        //养一只狗
//        Animal d1 = AnimalFactory.createAnimal("dog");Animal d1 = dogFactory.createAnimal();Animal d2 = dogFactory.createAnimal();//        //养一只猫
//        Animal c1 = AnimalFactory.createAnimal("cat");Animal c1 = catFactory.createAnimal();Animal c2 = catFactory.createAnimal();}
}

    单例模式：在整个java程序运行期间，内存中某一个对象有且仅只能有一个。笔试1. 饿汉式 工作开发中2. 懒汉式 面试的时候说，可能会涉及线程安全的问题。

饿汉式 不调用也有对象

点击查看代码

public class Student1 {private static Student1 student1 = new Student1();private Student1(){}public static Student1 getStudent1(){return student1;}
}

懒汉式 不调用student就一直是null只要调用了就返回student

点击查看代码

public class Student2 {private static Student2 student2;private Student2(){}public synchronized static Student2 getStudent2(){if(student2==null){// t1 , t2, t3student2 = new Student2();}return student2;}
}