public void Intercept(IInvocation invocation)
{
IStorageNode master = invocation.InvocationTarget as IStorageNode;
if (master.IsDead)
{
IChangeProxyTarget cpt = invocation as IChangeProxyTarget;
// 将补代理对象master更换为slave
cpt.ChangeProxyTarget(_slave);
// 测试中恢复master状态，以便看到随后调用仍然使用master这一效果
master.IsDead = false;
}
invocation.Proceed();
}
