十六、拦截器实现的细节

1. 拦截器细节

1. 前置处理按拦截器列表的顺序执行；
2. 后置处理按拦截器列表的逆序执行；
3. 后置处理的异常需捕获后统一抛出；

2. 代码示例

public class InterceptorChain {
  private List<IInterceptor> interceptorList = new ArrayList<>();

  public void registerInterceptor(IInterceptor interceptor) {
    interceptorList.add(interceptor);
  } 

  public void beforeHandle(Object obj, Callable task) {
    if (CollectionUtils.isEmpty(interceptorList)) {
      return;
    }
    for (IInterceptor interceptor : interceptorList) {
      interceptor.beforeHandle(obj, task);
    }
  }

  public void afterHandle(Object obj, Callable task) {
    if (CollectionUtils.isEmpty(interceptorList)) {
      return;
    }  
    
    List<Throwable> throwableList = new ArrayList<>;
    for(int i = interceptorList.size(); i > -1; i--) {
      try {
         interceptorList.get(i).afterHandle(obj, task);
      } catch (Throwable throwable) {
          throwableList.add(throwable);
      }
    }
    ExceptionUtils.throwExceptionIfNotEmpty(throwableList);
 }
}