Spring.NET.AOP - ExceptionHandlerAdvice 不替换自定义异常

问题描述

这是我的第一个，也是 Spring.NET 和 AOP 的初学者.

this is my first and also I am beginner in Spring.NET and also AOP.

我想使用 Aspect for Exception Hadling 来替换、包装和修改我的自定义异常.

I would like use Aspect for Exception Hadling for replacing, wrap and modify my custom exceptions.

首先我定义了一些实体和 DAO.从 DAO 中的 Save 方法中，我将抛出我的异常.

First I defined some entity and DAO. From method Save in DAO I will throw my exception.

仅供参考:这是一个愚蠢的样本

FYI: This is silly sample

实体:

namespace ExceptionHandlingTutorial.Entities
{
    public class Customer
    {
        public long Id { get; set; }
        public string Name { get; set; }
    }
}

DAO:

namespace ExceptionHandlingTutorial.Dao
{
    public interface ICustomerDao
    {
        void Save(Customer customer);
    }

    public class CustomerDao:ICustomerDao
    {
        #region Implementation of ICustomerDao

        public void Save(Customer customer)
        {
            throw new CustomerException(
                string.Format("Customer with id {0} already exist in repository",customer.Id));
        }

        #endregion
    }
}

CustomException 类定义在这里:

namespace ExceptionHandlingTutorial
{
    public class CustomerException : Exception
    {
        public CustomerException(string msg)
            : base(msg)
        {

        }
    }
}

在 app.config 中，我定义了 CustomerDao 对象和 ExceptionHandlerAdvice 对象，它们仅将 CustomerException 替换为 System.ArgumentException.

In app.config I defined CustomerDao object and ExceptionHandlerAdvice object which only replace CustomerException for System.ArgumentException.

我不确定 ExceptionHandlerAdvice 是否是自动代理，我也不知道它是如何识别目标的.

I am not sure if ExceptionHandlerAdvice is auto-proxy and also I don’t how it identified targets.

我相信它使用 SpEL 来定义规则，当出现异常时，它会抛出检查列表.好的，这种类型的例外在列表中，我将应用一些建议.

I believe that it uses SpEL for define rules and when there is some exception it throws check list.Ok this type of exception is in list some I will apply advice.

谁能向我解释一下这方面是如何确定目标的?例如，我只想将这个方面应用于少数对象而不是全部.

Can anybody explain to me how this aspect identified targets? For example I would like apply this aspect only for a few objects not all.

我使用参考文档第 14.3 章异常处理，但我找不到这些信息.

I use ref documentation Chapter 14.3 Exception handling but I couldnt find these information.

这是 app.config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>

  <configSections>
    <sectionGroup name="spring">
      <section name="context" type="Spring.Context.Support.ContextHandler, Spring.Core"/>
      <section name="objects" type="Spring.Context.Support.DefaultSectionHandler, Spring.Core"/>
    </sectionGroup>
  </configSections>

  <spring>

    <context>
      <resource uri="config://spring/objects"/>
    </context>

    <objects xmlns="http://www.springframework.net">

      <object id="customerDao"
              type="ExceptionHandlingTutorial.Dao.CustomerDao, ExceptionHandlingTutorial"/>

      <object id="exceptionHandlerAdvice"
              type="Spring.Aspects.Exceptions.ExceptionHandlerAdvice, Spring.Aop">

        <property name="ExceptionHandlers">
          <list>
            <value>on exception name CustomerException replace System.ArgumentException 'Something'</value>
          </list>
        </property>

      </object>

    </objects>

  </spring>
</configuration>

我的主要问题是，如果我在 DAO 上调用 Save 方法，它会抛出 CustomerException 异常类型，此异常不会被替换.为什么?

try
            {
                var context = ContextRegistry.GetContext();
                var customerDao = (ICustomerDao)context["customerDao"];

                customerDao.Save(new Customer { Id = 1, Name = "Customer_1" });
            }
            catch (Exception ex)
            {

                Console.WriteLine(string.Format("Exception type: {0}\nException message: {1}\n",
                    ex.GetType(),ex.Message));
            }

抛出的异常是 CustomerException 的类型，而不是 ArgumentException,

Thrown exception is type of CustomerException not ArgumentException,

当建议适用时，我也尝试使用 DSL 来定义规则:

Also I tried use DSL for defined rules when advice apply:

on exception (#e is T(ExceptionHandlingTutorial.CustomerException) translate new System.ArgumentException('XChange, Method Name'+ #method.Name, #e))

但仍然是抛出异常类型的 CustomerException.

But still is throw exception type of CustomerException.

感谢您的帮助.

推荐答案

Spring.NET aop 为要应用建议的对象动态创建代理.当您执行 var customerDao = (ICustomerDao)context["customerDao"]; 时，Spring.NET 会返回此代理.所以如果配置正确，你不会得到一个 CustomerDao 实例，而是一个来自 Spring 的实现 ICustomerDao 接口的 aop 代理.此代理拦截对 Save(...) 的调用并应用您的异常处理建议.

Spring.NET aop dynamically creates a proxy for the objects you want to apply advice to. Spring.NET returns this proxy when you do var customerDao = (ICustomerDao)context["customerDao"];. So when configured correctly, you don't get a CustomerDao instance, but an aop proxy from Spring implementing the ICustomerDao interface. This proxy intercepts the call to Save(...) and applies your exception handling advice.

然而，你没有配置ProxyFactory，所以你不会得到一个代理，而是在调用var customerDao = (ICustomerDao)时得到一个CustomerDao实例上下文["customerDao"];.您可以在调试器中进行检查；检查 customerDao 的(运行时)类型.

However, you haven't configured a ProxyFactory, so you will not get a proxy, but a CustomerDao instance when calling var customerDao = (ICustomerDao)context["customerDao"];. You can check this in the debugger; inspect the (runtime) type of customerDao.

配置代理工厂的方法有多种；我建议您使用 AdvisorAutoProxy 适用于您的情况，但您也可以使用普通的 ProxyFactoryObject 或其他 AutoProxy.

There are several methods to configure the proxy factory; I'd advise you to use an AdvisorAutoProxy for your case, but you can also configure it manually for each object using a plain ProxyFactoryObject or another AutoProxy.

使用 AdvisorAutoProxy 时，您必须将以下对象定义添加到您的配置中:

When using an AdvisorAutoProxy, you have to add the following object definitions to your configuration:

<object id="ExceptionAdvisorForSaveMethods"
        type="Spring.Aop.Support.RegularExpressionMethodPointcutAdvisor, Spring.Aop">
  <property name="advice" ref="exceptionHandlerAdvice"/>
  <property name="patterns">
    <list>
      <value>.*Save.*</value>
    </list>
  </property>
</object>

<object id="ProxyCreator"
        type="Spring.Aop.Framework.AutoProxy.DefaultAdvisorAutoProxyCreator, Spring.Aop" />

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