java常用设计模式(观察者模式)

一:观察者模式又可称为发布/订阅(Publish/Subscribe)模式,例如今天发工资了,大家手机都来短信通知了,快看啊,600.~,当到发工资的时候,会自动推送消息到每个人,假如你离职了,财务可以把你的手机移除,有新人入职,又可以添加.还可以给你涨工资601.

public interface Salary {//发送短信通知void sendmessage();//不给离职人员发void removeEmp(Employees employees);//给新入职人员发void addEmp(Employees employees);}

public interface Employees {public void receive(String salrayNum);}

public class Boss implements Salary {List<Employees> emp = new ArrayList<>();String salaryNum;@Overridepublic void removeEmp(Employees employees) {int i = emp.indexOf(employees);if (i>=0) {emp.remove(employees);System.out.println("老板移除了:"+((Employee)employees).name);}}@Overridepublic void addEmp(Employees employees) {emp.add(employees);}@Overridepublic void sendmessage() {for (int i = 0; i < emp.size(); i++) {emp.get(i).receive(salaryNum);}}       public void changeSalary(String salaryNum){this.salaryNum = salaryNum;System.out.println("老板发了"+salaryNum+"钱");this.sendmessage();}}

public class Employee implements Employees {public Boss boss;public String name;public String getName() {return name;}public Employee(String name,Boss boss) {this.name=name;this.boss=boss;boss.addEmp(this);}@Overridepublic void receive(String salaryNum) {System.out.println(this.name+"收到了:"+salaryNum+"钱");}}

public class Test {@SuppressWarnings("unused")public static void main(String[] args) {Boss boss = new Boss();Employees A = new Employee("A", boss);Employees B = new Employee("B", boss);Employees C = new Employee("C", boss);//boss.removeEmp(A);boss.changeSalary("500");}        //老板发了500钱         A收到了:500钱         B收到了:500钱         C收到了:500钱       //老板移除了:A        老板发了500钱        B收到了:500钱        C收到了:500钱 }