struts2模拟拦截器实现的小例子

public interface Interceptor {
    void interceptor(ActionInvocation invocation);
}

public class FirstInterceptor implements Interceptor {
    public void interceptor(ActionInvocation invocation) {
        System.out.println(1);
        invocation.invoke();
        System.out.println(-1);
    }
}

public class SecondInterceptor implements Interceptor{
    public void interceptor(ActionInvocation invocation) {
        System.out.println(2);
        invocation.invoke();
        System.out.println(-2);
    }
}

public class ThirdInterceptor implements Interceptor{
    public void interceptor(ActionInvocation invocation) {
        System.out.println(3);
        invocation.invoke();
        System.out.println(-3);
    }
}

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

 1 public class ActionInvocation {
 2     List<Interceptor> interceptors = new ArrayList<Interceptor>();
 3     int index = -1;
 4     Action a = new Action();
 5     
 6     public ActionInvocation(){
 7         this.interceptors.add(new FirstInterceptor());
 8         this.interceptors.add(new SecondInterceptor());
 9         this.interceptors.add(new ThirdInterceptor());
10     }
11     public void invoke() {
12         index++;
13         
14         if (index >= this.interceptors.size()) {
15             a.execute();
16         } else {
17             this.interceptors.get(index).interceptor(this);
18         }
19     }
20 }

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