模仿Struts2的Interceptor拦截器实现

模仿Struts2的Interceptor拦截器实现

public interface Invocation {

    public Object invoke();

}

public interface Interceptor {

    public Object intercept(Invocation invocation);

}

public class Target {

    public Object execute() {
        System.out.println("Targer.execute()");
        return "Targer-execute";
    }
}

public class InvocationChain implements Invocation {

    private Iterator<Interceptor> iterator = null;

    private Target target = new Target();

    public void init(List<Interceptor> interceptors) {
        List<Interceptor> interceptorsList = new ArrayList<Interceptor>(interceptors);
        this.iterator = interceptorsList.iterator();
    }

    public Object invoke() {
        if(iterator.hasNext()) {
            return iterator.next().intercept(this);
        } else {
            return target.execute();
        }
    }

}

public class IntOne implements Interceptor {

    public Object intercept(Invocation invocation) {
        Object result = null;
        System.out.println("IntOne.intercept()-begin");
        result = invocation.invoke();
        System.out.println("IntOne.intercept()-end");
        return result;
    }

}

public class IntTwo implements Interceptor {

    public Object intercept(Invocation invocation) {
        Object result = null;
        System.out.println("IntTwo.intercept()-begin");
        result = invocation.invoke();
        System.out.println("IntTwo.intercept()-end");
        return result;
    }

}

public class Demo {

    /**
     * @param args
     */
    public static void main(String[] args) {
        List<Interceptor> interceptors = new ArrayList<Interceptor>();
        interceptors.add(new IntOne());
        interceptors.add(new IntTwo());
        InvocationChain chain = new InvocationChain();
        chain.init(interceptors);
        System.out.println(chain.invoke());
    }

}