观察者模式

package observer_pattern;

public interface Observer {
	boolean monitor(Teacher teacher);//监听不同老师
	int hint();//监听到了之后的放哨行为
	boolean changelister();//管理听者
}

package observer_pattern;

public class Monitor_Observer implements Observer {

	 
	Teacher teacher ;
	int type;
	public boolean monitor(Teacher teacher) {
		// TODO Auto-generated method stub
		this.teacher  = teacher;
		return true;
	}

	@Override
	public int hint() {
		// TODO Auto-generated method stub
		this.type = teacher.type;
		if(type==1){
			 
			System.out.println("班长举右手示意数学老师来了");
		}
		else{
			 
			System.out.println("班长举左手示意语文老师来了");
		}
		return this.type;
	}

	@Override
	public boolean changelister() {
		// TODO Auto-generated method stub
		return false;
	}

}

package observer_pattern;

public interface Listern {
	 
	void action(int message);
}

package observer_pattern;

public class LaoWang implements Listern {

	@Override
	 
		// TODO Auto-generated method stub
		public void action(int message) {
			// TODO Auto-generated method stub
			if(message==1){
				System.out.println("我拿起数学本");
			}
			else{
				System.out.println(message);
				System.out.println("我拿起语文本");
			}
		
	}

}

package observer_pattern;

public class XiaoMing implements Listern {

	@Override
	public void action(int message) {
		// TODO Auto-generated method stub
		if(message==1){
			System.out.println("我拿起数学本");
		}
		else{
			
			System.out.println("我拿起语文本");
		}
	}

}

package observer_pattern;

public abstract class Teacher {
	 
	int type;
	abstract int teacher_type();
}

package observer_pattern;

public class Math_Teacher extends Teacher {

	Math_Teacher(){
		teacher_type();
	}
	@Override
	int teacher_type() {
		// TODO Auto-generated method stub
		this.type = 1;
		return type;
	}

}

package observer_pattern;

public class Chinese_Teacher extends Teacher {

	 
	Chinese_Teacher(){
		teacher_type();
	}
	
	public int teacher_type() {
		// TODO Auto-generated method stub
		this.type = 2;
		return type;
	}

}

package observer_pattern;

public class test {
	public static void main(String[] args) {
		
		Monitor_Observer monitor = new Monitor_Observer();
		monitor.monitor(new Math_Teacher());
		LaoWang lw = new LaoWang();
		XiaoMing xm  = new XiaoMing();
		lw.action(monitor.hint());
		xm.action(monitor.hint());
	}
}