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{
    @Override
    public void eat() {
        System.out.println("猫吃鱼");
    }

    @Override
    public void sleep() {
        System.out.println("猫蜷着睡");
    }
}


public class Dog extends Animal {
    @Override
    public void eat() {
        System.out.println("狗吃肉");
    }

    @Override
    public 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{
    @Override
    public void eat() {
        System.out.println("猫吃鱼");
    }

    @Override
    public void sleep() {
        System.out.println("猫蜷着睡");
    }
}


public class Dog extends Animal {
    @Override
    public void eat() {
        System.out.println("狗吃肉");
    }

    @Override
    public void sleep() {
        System.out.println("狗侧着睡");
    }
}



public abstract class AnimalFactory {
   public abstract Animal createAnimal();
}


public class CatFactory extends AnimalFactory{
    @Override
    public Animal createAnimal() {
        return new Cat();
    }
}


public class DogFactory extends AnimalFactory{
    @Override
    public 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, t3
            student2 = new Student2();
        }

        return student2;
    }
}