在nhibernate中注册多个IInterceptor。

Question

有没有办法在nhibernate中注册多个IInterceptor？

在Hhibernate 3.1.0.4000中无法使用。

config.SetInterceptor(new ContextAwareInterceptor());
config.SetInterceptor(new ContextAwareCommandInterceptor());
config.SetInterceptor(new SqlInterceptor());

Answer 1

你不能这样做，一个会话只能有一个拦截器。一个会话只能有一个拦截器。

你应该研究一下 事件 而不是。

Answer 2

你可以通过使用复合拦截器来实现。下面是一个对我来说很有效的实现。只是要注意，如果你有多个拦截器实现了一个返回值的方法（像 GetEntity())，在某些情况下，第一个被返回，而另一些(Like FindDirty() 和 OnPrepareStatement())的结果相结合。带测试的完整列表 此处.

using System.Collections;
using System.Collections.Generic;
using System.Linq;
using MoreLinq;
using NHibernate;
using NHibernate.SqlCommand;
using NHibernate.Type;

public class CompositeInterceptor : IInterceptor
{
    private readonly IEnumerable<IInterceptor> _interceptors;

    public CompositeInterceptor(IEnumerable<IInterceptor> interceptors)
    {
        _interceptors = interceptors.ToList();
    }

    public void AfterTransactionBegin(ITransaction tx)
    {
        _interceptors.ForEach(x => x.AfterTransactionBegin(tx));
    }

    public void AfterTransactionCompletion(ITransaction tx)
    {
        _interceptors.ForEach(x => x.AfterTransactionCompletion(tx));
    }

    public void BeforeTransactionCompletion(ITransaction tx)
    {
        _interceptors.ForEach(x => x.BeforeTransactionCompletion(tx));
    }

    public int[] FindDirty(object entity, object id, object[] currentState, 
        object[] previousState, string[] propertyNames, IType[] types)
    {
        var results = _interceptors
            .Select(interceptor => interceptor.FindDirty(entity, id,
                currentState, previousState, propertyNames, types))
            .Where(result => result != null)
            .SelectMany(x => x)
            .Distinct()
            .ToArray();
        return !results.Any() ? null : results;
    }

    public object GetEntity(string entityName, object id)
    {
        return _interceptors
            .Select(interceptor => interceptor.GetEntity(entityName, id))
            .FirstOrDefault(result => result != null);
    }

    public string GetEntityName(object entity)
    {
        return _interceptors
            .Select(interceptor => interceptor.GetEntityName(entity))
            .FirstOrDefault(result => result != null);
    }

    public object Instantiate(string entityName, EntityMode entityMode, object id)
    {
        return _interceptors
            .Select(interceptor => interceptor.Instantiate(entityName, entityMode, id))
            .FirstOrDefault(result => result != null);
    }

    public bool? IsTransient(object entity)
    {
        return _interceptors
            .Select(interceptor => interceptor.IsTransient(entity))
            .FirstOrDefault(result => result != null);
    }

    public void OnCollectionRecreate(object collection, object key)
    {
        _interceptors.ForEach(x => x.OnCollectionRecreate(collection, key));
    }

    public void OnCollectionRemove(object collection, object key)
    {
        _interceptors.ForEach(x => x.OnCollectionRemove(collection, key));
    }

    public void OnCollectionUpdate(object collection, object key)
    {
        _interceptors.ForEach(x => x.OnCollectionUpdate(collection, key));
    }

    public void OnDelete(object entity, object id, object[] state, 
        string[] propertyNames, IType[] types)
    {
        _interceptors.ForEach(x => x.OnDelete(entity, id, state, propertyNames, types));
    }

    public bool OnFlushDirty(object entity, object id, object[] currentState, 
        object[] previousState, string[] propertyNames, IType[] types)
    {
        return _interceptors.Count(interceptor => interceptor.OnFlushDirty(
            entity, id, currentState, previousState, propertyNames, types)) > 0;
    }

    public bool OnLoad(object entity, object id, object[] state, 
        string[] propertyNames, IType[] types)
    {
        return _interceptors.Count(interceptor => interceptor.OnLoad(
            entity, id, state, propertyNames, types)) > 0;
    }

    public SqlString OnPrepareStatement(SqlString sql)
    {
        return _interceptors.Aggregate(sql, (current, interceptor) => 
            interceptor.OnPrepareStatement(current));
    }

    public bool OnSave(object entity, object id, object[] state, 
        string[] propertyNames, IType[] types)
    {
        return _interceptors.Count(interceptor => interceptor.OnSave(
            entity, id, state, propertyNames, types)) > 0;
    }

    public void PostFlush(ICollection entities)
    {
        _interceptors.ForEach(x => x.PostFlush(entities));
    }

    public void PreFlush(ICollection entities)
    {
        _interceptors.ForEach(x => x.PreFlush(entities));
    }

    public void SetSession(ISession session)
    {
        _interceptors.ForEach(x => x.SetSession(session));
    }
}