Interceptor的实现

public interface Action {
  public String execute() throws Exception;
}

public class TestAction implements Action {

    public String execute() throws Exception {
       System.out.println("action exe");
       return "success";
    }

}

public interface Interceptor {
   public String intercept(ActionInvocation invocation) throws Exception;
}

public class Test1Intercpetor implements Interceptor{

    public String intercept(ActionInvocation invocation) throws Exception{
         System.out.println("hello!in test1");
         String code= invocation.invoke();
         System.out.println("end!in test1");
         return code;
    }

}

public class Test2Intercpetor implements Interceptor{

    public String intercept(ActionInvocation invocation) throws Exception{
         System.out.println("hello!in test2");
         String code= invocation.invoke();
         System.out.println("end!in test2");
         return code;
    }

}

public interface ActionInvocation {
  public  String invoke() throws Exception  ;
}


public class DefaultInvocation  implements ActionInvocation{

    private List<Interceptor> interceptors =new ArrayList<Interceptor>();
    private int index=-1;
    private String result;
    public String invoke() throws Exception {

        if(index==interceptors.size()-1){
             result=action.execute();
        }else
        {
           index++;
           result=((Interceptor)interceptors.get(index)).intercept(this);
           System.out.println("????"+result);
          
       }
        return result;
    }

    public void addInterceptor(Interceptor interceptor){
        interceptors.add(interceptor);
    }

    private Action action;
    public Action getAction() {
        return action;
    }
    public void setAction(Action action) {
        this.action = action;
    }
   

}


public class Test {
public static void main(String[] args){
    DefaultInvocation d=new DefaultInvocation();
    d.setAction(new TestAction());
    d.addInterceptor(new Test1Intercpetor());
    d.addInterceptor(new Test2Intercpetor());
        try {
            d.invoke();
        } catch (Exception ex) {
            Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
        }
}