拦截器模拟

public class Main {
	public static void main(String[] args) {
		new ActionInvocation().invoke();
	}
}


public interface Interceptor { //定义接口
	public void intercept(ActionInvocation invocation) ;
}


import java.util.ArrayList;
import java.util.List;

public class ActionInvocation {
	List<Interceptor> interceptors = new ArrayList<Interceptor>(); // 定义一系列接口集合
	int index = -1;
	Action a = new Action();

	public ActionInvocation() {
		this.interceptors.add(new FirstInterceptor()); // 向集合中添加
		this.interceptors.add(new SecondInterceptor());

	}

	public void invoke() {
		index++;
		if (index >= this.interceptors.size()) { // 循环完成
			a.execute();
		} else {
			this.interceptors.get(index).intercept(this); //用index上的interceptors调用intercept
		}
	}
}


public class FirstInterceptor implements Interceptor { // 实现Interceptor接口

	public void intercept(ActionInvocation invocation) {
		System.out.println(1);
		invocation.invoke();
		System.out.println(-1);
	}

}


public class SecondInterceptor implements Interceptor {// 实现Interceptor接口

	public void intercept(ActionInvocation invocation) {
		System.out.println(2);
		invocation.invoke();
		System.out.println(-2);
	}

}


public class Action {
	public void execute() {
		System.out.println("execute!");
	}
}