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); 
        } 
}