单例模式
就是一个应用程序中,某个类的实例对象只有一个,你没有办法去new,因为构造器是被private修饰的,一般通过getInstance()的方法来获取它们的实例
饿汉式写法
public class Singleton {
private static Singleton instance = new Singleton();
private Singleton (){}
public static Singleton getInstance() {
return instance;
}
}
懒汉式写法(线程安全)
public class Singleton {
private static Singleton instance;
private Singleton (){}
public static synchronized Singleton getInstance() {
if (instance == null) {
instance = new Singleton();
}
return instance;
}
}
静态内部类
public class Singleton {
private static class SingletonHolder {
private static final Singleton INSTANCE = new Singleton();
}
private Singleton (){}
public static final Singleton getInstance() {
return SingletonHolder.INSTANCE;
}
}
观察者模式
对象间一对多的依赖关系,当一个对象的状态发生改变时,所有依赖于它的对象都得到通知并被自动更新
情景:小王和小李喜欢小美,时刻关注着她的行为
public interface Person {
//小王和小李通过这个接口可以接收到小美发过来的消息
void getMessage(String s);
}
public class LaoWang implements Person {
private String name = "小王";
public LaoWang() {
}
@Override
public void getMessage(String s) {
System.out.println(name + "接到了小美打过来的电话,电话内容是:" + s);
}
}
public class LaoLi implements Person {
private String name = "小李";
public LaoLi() {
}
@Override
public void getMessage(String s) {
System.out.println(name + "接到了小美打过来的电话,电话内容是:->" + s);
}
}
public class XiaoMei {
List<Person> list = new ArrayList<Person>();
public XiaoMei(){
}
//把所有暗恋者加进来
public void addPerson(Person person){
list.add(person);
}
//遍历list,把自己的通知发送给所有暗恋自己的人
public void notifyPerson() {
for(Person person:list){
person.getMessage("你们过来吧,谁先过来谁就能陪我一起玩儿游戏!");
}
}
}
装饰者模式
对已有的业务逻辑进一步的封装,使其增加额外的功能,如Java中的IO流就使用了装饰者模式,用户在使用的时候,可以任意组装,达到自己想要的效果
public class Food {
private String food_name;
public Food() {
}
public Food(String food_name) {
this.food_name = food_name;
}
public String make() {
return food_name;
};
}
//面包类
public class Bread extends Food {
private Food basic_food;
public Bread(Food basic_food) {
this.basic_food = basic_food;
}
public String make() {
return basic_food.make()+"+面包";
}
}
//奶油类
public class Cream extends Food {
private Food basic_food;
public Cream(Food basic_food) {
this.basic_food = basic_food;
}
public String make() {
return basic_food.make()+"+奶油";
}
}
//蔬菜类
public class Vegetable extends Food {
private Food basic_food;
public Vegetable(Food basic_food) {
this.basic_food = basic_food;
}
public String make() {
return basic_food.make()+"+蔬菜";
}
}
public class Test {
public static void main(String[] args) {
Food food = new Bread(new Vegetable(new Cream(new Food("香肠"))));
System.out.println(food.make());
}
}
工厂模式
简单工厂模式:一个抽象的接口,多个抽象接口的实现类,一个工厂类,用来实例化抽象的接口
// 抽象产品类
abstract class Car {
public void run();
public void stop();
}
// 具体实现类
class Benz implements Car {
public void run() {
System.out.println("Benz开始启动了。。。。。");
}
public void stop() {
System.out.println("Benz停车了。。。。。");
}
}
class Ford implements Car {
public void run() {
System.out.println("Ford开始启动了。。。");
}
public void stop() {
System.out.println("Ford停车了。。。。");
}
}
// 工厂类
class Factory {
public static Car getCarInstance(String type) {
Car c = null;
if ("Benz".equals(type)) {
c = new Benz();
}
if ("Ford".equals(type)) {
c = new Ford();
}
return c;
}
}
public class Test {
public static void main(String[] args) {
Car c = Factory.getCarInstance("Benz");
if (c != null) {
c.run();
c.stop();
} else {
System.out.println("造不了这种汽车。。。");
}
}
}
工厂方法模式:由抽象工厂的子类去实例化产品
// 抽象产品角色
public interface Moveable {
void run();
}
// 具体产品角色
public class Plane implements Moveable {
@Override
public void run() {
System.out.println("plane....");
}
}
public class Broom implements Moveable {
@Override
public void run() {
System.out.println("broom.....");
}
}
// 抽象工厂
public abstract class VehicleFactory {
abstract Moveable create();
}
// 具体工厂
public class PlaneFactory extends VehicleFactory {
public Moveable create() {
return new Plane();
}
}
public class BroomFactory extends VehicleFactory {
public Moveable create() {
return new Broom();
}
}
// 测试类
public class Test {
public static void main(String[] args) {
VehicleFactory factory = new BroomFactory();
Moveable m = factory.create();
m.run();
}
}
抽象工厂模式:与工厂方法模式不同的是,工厂方法模式中的工厂只生产单一的产品,而抽象工厂模式中的工厂生产多个产品
/抽象工厂类
public abstract class AbstractFactory {
public abstract Vehicle createVehicle();
public abstract Weapon createWeapon();
public abstract Food createFood();
}
//具体工厂类,其中Food,Vehicle,Weapon是抽象类,
public class DefaultFactory extends AbstractFactory{
@Override
public Food createFood() {
return new Apple();
}
@Override
public Vehicle createVehicle() {
return new Car();
}
@Override
public Weapon createWeapon() {
return new AK47();
}
}
//测试类
public class Test {
public static void main(String[] args) {
AbstractFactory f = new DefaultFactory();
Vehicle v = f.createVehicle();
v.run();
Weapon w = f.createWeapon();
w.shoot();
Food a = f.createFood();
a.printName();
}
}
生产者/消费者模式
某个模块负责产生数据,这些数据由另一个模块来负责处理,产生数据的模块,就形象地称为生产者;而处理数据的模块,就称为消费者。在生产者与消费者之间在加个缓冲区,我们形象的称之为仓库,生产者负责往仓库了进商品,而消费者负责从仓库里拿商品,这就构成了生产者消费者模式
//此类是共享数据区域
public class SyncStack {
private String[] str = new String[10];
private int index;
//供生产者调用
public synchronized void push(String sst){
if(index == sst.length()){
try {
wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
this.notify();//唤醒在此对象监视器上等待的单个线程
str[index] = sst;
index++;
}
//供消费者调用
public synchronized String pop(){
if(index == 0){
try {
wait();
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
this.notify();
index--;
String product = str[index];
return product;
}
//就是定义一个返回值为数组的方法,返回的是一个String[]引用
public String[] pro(){
return str;
}
}
public class Producter implements Runnable {
//创建生产者
private SyncStack stack;
public Producter(SyncStack stack){
this.stack = stack;
}
public void run(){
for(int i = 0;i<stack.pro().length;i++){
String producter = "产品" + i;
stack.push(producter);
System.out.println("生产了:" + producter);
try {
Thread.sleep(200);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
public class Consumer implements Runnable {
//创建消费者
private SyncStack stack;
public Consumer(SyncStack stack){
this.stack = stack;
}
public void run(){
for(int i=0;i<stack.pro().length;i++){
String consumer = stack.pop();
System.out.println("消费了:" + consumer );
try {
Thread.sleep(400);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
public class TestDeam {
//测试类
public static void main(String[] args) {
SyncStack stack = new SyncStack();
Consumer p = new Consumer(stack);
Producter c = new Producter(stack);
new Thread(p).start();
new Thread(c).start();
}
}
代理模式
//代理接口
public interface ProxyInterface {
//需要代理的是结婚这件事,如果还有其他事情需要代理
void marry();
}
public class WeddingCompany implements ProxyInterface {
private ProxyInterface proxyInterface;
public WeddingCompany(ProxyInterface proxyInterface) {
this.proxyInterface = proxyInterface;
}
@Override
public void marry() {
System.out.println("我们是婚庆公司的");
System.out.println("我们在做结婚前的准备工作");
System.out.println("可以开始结婚了");
proxyInterface.marry();
}
}
public class NormalHome implements ProxyInterface{
@Override
public void marry() {
System.out.println("我们结婚啦~");
}
}
public class Test {
public static void main(String[] args) {
ProxyInterface proxyInterface = new WeddingCompany(new NormalHome());
proxyInterface.marry();
}
}