public Object doNext() throws Exception {
if (++index < interceptors.length) { // ++index 用于将-1转化为0
InterceptorDelegate interceptor = interceptors[index];
//
rose.addAfterCompletion(interceptor);
Object instruction = interceptor.roundInvocation(rose.getInvocation(), this);
//
if (debugEnabled) {
logger.debug("interceptor[" + interceptor.getName() + "] do round and return '"
+ instruction + "'");
}