设计模式之观察者模式详解

/**
 * 抽象观察者
 */
public interface IWatcher {
    
    public void getNotice(String str);
}

/**
 * 抽象主题：工资接口
 */
public interface ISalary {
    
    public void addWatcher(IWatcher watcher);
    
    public void removeWatcher(IWatcher watcher);
    
    public void notifyAll(String str);
}

/**
 * 具体观察者：员工
 */
public class Emp implements IWatcher {

    @Override
    public void getNotice(String str) {
        
        System.out.println("员工" + str);
    }

}

/**
 * 具体观察者：经理
 */
public class Manager implements IWatcher {

    @Override
    public void getNotice(String str) {
        
        System.out.println("经理" + str);
    }

}

/**
 * 具体主题：工资
 */
public class Salary implements ISalary {

    //存放观察者：员工
    private List<IWatcher> watcherList = new ArrayList<IWatcher>();
    
    @Override
    public void addWatcher(IWatcher watcher) {
        watcherList.add(watcher);

    }

    @Override
    public void removeWatcher(IWatcher watcher) {
        watcherList.remove(watcher);

    }

    @Override
    public void notifyAll(String str) {
        for (IWatcher watcher: watcherList) {
            watcher.getNotice(str);
        }
    }
}

/**
 * 测试类
 */
public class Test {

    public static void main(String[] args) {
        
        //工资
        ISalary salary = new Salary();
        //员工
        IWatcher emp = new Emp();
        //经理
        IWatcher manager = new Manager();
        
        //添加观察者
        salary.addWatcher(emp);
        salary.addWatcher(manager);
        
        salary.notifyAll("发工资了！");
    }
}