Spring Aop 错误之：No MethodInvocation found ... the ExposeInvocationInterceptor is upfront in the inter...

分析这个问题需要先了解一个东西：ExposeInvocationInterceptor

1.从官方得到以下相关信息：

 可以获知，当使用 AspectJ 时，spring 会添加一个连接器放到 advice 链的开头。但是为何要放这个东西呢？它是干嘛的？

2.看源码：

**
 * Interceptor that exposes the current {@link org.aopalliance.intercept.MethodInvocation}
 * as a thread-local object. We occasionally need to do this; for example, when a pointcut
 * (e.g. an AspectJ expression pointcut) needs to know the full invocation context.
 *
 * <p>Don't use this interceptor unless this is really necessary. Target objects should
 * not normally know about Spring AOP, as this creates a dependency on Spring API.
 * Target objects should be plain POJOs as far as possible.
 *
 * <p>If used, this interceptor will normally be the first in the interceptor chain.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 */
@SuppressWarnings("serial")
public class ExposeInvocationInterceptor implements MethodInterceptor, PriorityOrdered, Serializable {

    /** Singleton instance of this class */
    public static final ExposeInvocationInterceptor INSTANCE =