AOP的两个应用：实体集更新(DateEntityListUpdate)、延迟加载(LazyLoad)

在FaibClass.Data中，有两个AOP的应用，它们分别是实体集更新(DateEntityListUpdate)、延迟加载(LazyLoad)，目前的DataEntity继承于ContextBoundObject，刚刚从网上看到ContextBoundObject的损耗非常大，但自己测试了一下，应该说影响不是很大，所以暂时不打算使用静态注入了。

      注，两个AOP都采用Attribute--Property--Sink的结构，每个类的具体功能请查阅相关的技术资料。

一、实体集更新(DateEntityListUpdate)
      在前台设置一个实体的属性，我们在更新整个实体集到数据库的时候，并不知道哪些属性更改过，如果全部更新，将造成不必要的浪费，所以引入了这个概念。如果我们不这样做，模型类的每个属性set后将添加一句代码AddUpdateColumn。
      这里使用了.Net的消息链进行处理，因为实体类上还可能使用了其他的AOP。

EntityListUpdatableAttribute类

Code
//*******************************************************************
// 模块:指示实体对象可被集合更新
// 日期:2009-7-29 1:05
// 作者:Faib
// 版权:Copyright Faib Studio 2009
// 官网:http://www.faib.net.cn
// 邮箱:[email protected]
// 备注:
//*******************************************************************

using System;
using System.Runtime.Remoting.Contexts;
using System.Runtime.Remoting.Activation;

using FaibClass.Data.Aspect;

namespace FaibClass.Data
{
    /// <summary>
    /// 指示实体的属性更改后,可以使用Update更新整个实体集,如果不指定此特性,实体的DataState无法置为Modified。
    /// </summary>
    [AttributeUsage(AttributeTargets.Class, AllowMultiple=false)]
    public class EntityListUpdatableAttribute : Attribute, IContextAttribute, IContextProperty
    {
        internal static string propertyName = "EntityListUpdatable";

        /// <summary>
        /// 构造属性。
        /// </summary>
        public EntityListUpdatableAttribute()
        {
        }

        string IContextProperty.Name
        {
            get { return propertyName; }
        }

        void IContextProperty.Freeze(Context newContext)
        {
        }

        bool IContextProperty.IsNewContextOK(Context newCtx)
        {
            return true;
        }

        void IContextAttribute.GetPropertiesForNewContext(IConstructionCallMessage ctorMsg)
        {
            IContextProperty interceptProperty = new EntityListUpdatableProperty();
            ctorMsg.ContextProperties.Add(interceptProperty);
        }

        bool IContextAttribute.IsContextOK(Context ctx, IConstructionCallMessage ctorMsg)
        {
            if (ctx.GetProperty(propertyName) == null)
            {
                return false;
            }

            return true;
        }
    }
}

EntityListUpdatableProperty类

Code
//*******************************************************************
// 模块:实体集更新的上下文属性
// 日期:2009-9-19 14:24:24
// 作者:Faib
// 版权:Copyright Faib Studio 2009
// 官网:http://www.faib.net.cn
// 邮箱:[email protected]
// 备注:
//*******************************************************************
using System;
using System.Runtime.Remoting.Messaging;
using System.Runtime.Remoting.Contexts;

namespace FaibClass.Data.Aspect
{
    /// <summary>
    /// 实体集更新的上下文属性。
    /// </summary>
    internal class EntityListUpdatableProperty : IContextProperty, IContributeObjectSink
    {

        void IContextProperty.Freeze(Context newContext)
        {
        }

        string IContextProperty.Name
        {
            get { return EntityListUpdatableAttribute.propertyName; }
        }

        bool IContextProperty.IsNewContextOK(Context newCtx)
        {
            EntityListUpdatableProperty property = 
                newCtx.GetProperty(EntityListUpdatableAttribute.propertyName) as EntityListUpdatableProperty;

            if (property == null)
            {
                return false;
            }

            return true;
        }

        IMessageSink IContributeObjectSink.GetObjectSink(MarshalByRefObject obj, IMessageSink nextSink)
        {
            IMessageSink sink = new EntityListUpdatableSink(obj, nextSink);
            return sink;
        }
    }
}

EntityListUpdatableSink类

Code
//*******************************************************************
// 模块:用于处理属性修改后的消息接收器
// 日期:2009-9-19 14:24:12
// 作者:Faib
// 版权:Copyright Faib Studio 2009
// 官网:http://www.faib.net.cn
// 邮箱:[email protected]
// 备注:
//*******************************************************************
using System;
using System.Reflection;
using System.Runtime.Remoting.Messaging;

namespace FaibClass.Data.Aspect
{
    /// <summary>
    /// 用于处理属性修改后的消息接收器。
    /// </summary>
    internal class EntityListUpdatableSink : IMessageSink
    {
        private IMessageSink m_nextSink;
        private MarshalByRefObject m_target;
        private static object syncRoot = new object();
        public EntityListUpdatableSink(MarshalByRefObject target, IMessageSink nextSink)
        {
            lock (syncRoot)
            {
                m_target = target;
                m_nextSink = nextSink;
            }
        }

        public IMessage SyncProcessMessage(IMessage msg)
        {
            IMethodReturnMessage returnedMessage;
            HandleMessage(msg, false, out returnedMessage);
            return returnedMessage;
        }

        public IMessageCtrl AsyncProcessMessage(IMessage msg, IMessageSink replySink)
        {
            IMethodReturnMessage returnedMessage;
            HandleMessage(msg, true, out returnedMessage);
            return m_nextSink.AsyncProcessMessage(msg, replySink);
        }

        public IMessageSink NextSink
        {
            get { return m_nextSink; }
        }

        private void HandleMessage(IMessage msg, bool IsAsync, out IMethodReturnMessage returnedMessage)
        {
            returnedMessage = null;
            if (!IsAsync)
            {
                if (msg is IMethodCallMessage)
                {
                    IMethodCallMessage mcm = (IMethodCallMessage)msg;

                    bool isFill = (bool)m_target.GetType().GetProperty("InnerIsFill", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(m_target, null);
                    
                    bool isProperty = !isFill && ((mcm.MethodName.Length > 4 &&
                        mcm.MethodName.Substring(0, 4) == "set_" && mcm.MethodName != "set_InnerIsFill" &&
                        mcm.MethodName != "set_InnerDataState" &&
                        mcm.MethodName != "set_InnerData") || mcm.MethodName == "FieldSetter");
                    object oldvalue = null, newvalue = null;

                    MemberInfo minfo = null;
                    string propertyName = string.Empty;
                    //取原来的值
                    if (isProperty)
                    {
                        if (mcm.MethodName == "FieldSetter")
                            propertyName = mcm.InArgs[1].ToString();
                        else
                            propertyName = mcm.MethodName.Replace("set_", "");
                        minfo = Utility.GetMember(m_target.GetType(), propertyName);
                        if (minfo == null)
                            isProperty = false;
                        else if (minfo.IsDefined(typeof(DataColumnAttribute), true))
                            oldvalue = Utility.GetMemberValue(m_target, minfo, propertyName);
                    }

                    returnedMessage = (IMethodReturnMessage)m_nextSink.SyncProcessMessage(msg);
                    
                    if (isProperty)
                    {
                        //新的值
                        newvalue = Utility.GetMemberValue(m_target, minfo, propertyName);
                        if (!newvalue.Equals(oldvalue))
                        {
                            //调用内部方法添加修改了的列
                            m_target.GetType().InvokeMember("AddUpdateColumn", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.InvokeMethod, null, m_target, new object[] { mcm.MethodName.Replace("set_", "") });
                        }
                    }
                }
                else
                {
                    returnedMessage = (IMethodReturnMessage)m_nextSink.SyncProcessMessage(msg);
                }
            }
            else
            {
                returnedMessage = null;
            }
        }

    }
}

二、延迟加载(LazyLoad)
     没有仔细研究过其他框架的延迟加载是怎么实现的，自己还是基于.Net的消息机制做了这个功能。

LazyLoadableAttribute类

Code
//*******************************************************************
// 模块:延迟加载的属性
// 日期:2009-9-19 14:23:22
// 作者:Faib
// 版权:Copyright Faib Studio 2009
// 官网:http://www.faib.net.cn
// 邮箱:[email protected]
// 备注:
//*******************************************************************
using System;
using System.Runtime.Remoting.Contexts;
using System.Runtime.Remoting.Activation;

using FaibClass.Data.Aspect;

namespace FaibClass.Data
{
    /// <summary>
    /// 指示该实体中的子实体集、引用实体、引用属性可延迟载入。
    /// </summary>
    [AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
    public class LazyLoadableAttribute : Attribute, IContextAttribute, IContextProperty
    {

        internal static string propertyName = "LazyLoadable";
     
        /// <summary>
        /// 构造属性。
        /// </summary>
        public LazyLoadableAttribute()
        {
        }

        string IContextProperty.Name
        {
            get { return propertyName; }
        }

        void IContextProperty.Freeze(Context newContext)
        {
        }

        bool IContextProperty.IsNewContextOK(Context newCtx)
        {
            return true;
        }

        void IContextAttribute.GetPropertiesForNewContext(IConstructionCallMessage ctorMsg)
        {
            IContextProperty interceptProperty = new LazyLoadableProperty();
            ctorMsg.ContextProperties.Add(interceptProperty);
        }

        bool IContextAttribute.IsContextOK(Context ctx, IConstructionCallMessage ctorMsg)
        {
            if (ctx.GetProperty(propertyName) == null)
            {
                return false;
            }
              
            return true;
        }
    }
}

LazyLoadableProperty类

Code
//*******************************************************************
// 模块:延迟加载的上下文属性
// 日期:2009-9-19 14:09:46
// 作者:Faib
// 版权:Copyright Faib Studio 2009
// 官网:http://www.faib.net.cn
// 邮箱:[email protected]
// 备注:
//*******************************************************************
using System;
using System.Runtime.Remoting.Messaging;
using System.Runtime.Remoting.Contexts;

namespace FaibClass.Data.Aspect
{
    /// <summary>
    /// 延迟加载的上下文属性。
    /// </summary>
    internal class LazyLoadableProperty : IContextProperty, IContributeObjectSink
    {

        void IContextProperty.Freeze(Context newContext)
        {
        }

        string IContextProperty.Name
        {
            get { return LazyLoadableAttribute.propertyName; }
        }

        bool IContextProperty.IsNewContextOK(Context newCtx)
        {
            LazyLoadableProperty property = 
                newCtx.GetProperty(LazyLoadableAttribute.propertyName) as LazyLoadableProperty;

            if (property == null)
            {
                return false;
            }

            return true;
        }

        IMessageSink IContributeObjectSink.GetObjectSink(MarshalByRefObject obj, IMessageSink nextSink)
        {
            IMessageSink sink = new LazyLoadableSink(obj, nextSink);
            return sink;
        }
    }
}

LazyLoadableSink类

Code
//*******************************************************************
// 模块:实现延迟载入的消息接收器
// 日期:2009-9-19 14:08:58
// 作者:Faib
// 版权:Copyright Faib Studio 2009
// 官网:http://www.faib.net.cn
// 邮箱:[email protected]
// 备注:
//*******************************************************************
using System;
using System.Reflection;
using System.Runtime.Remoting.Messaging;

using FaibClass.Data.Operation;

namespace FaibClass.Data.Aspect
{
    /// <summary>
    /// 实现延迟载入的消息接收器。
    /// </summary>
    internal class LazyLoadableSink : IMessageSink
    {
        private IMessageSink m_nextSink;
        private MarshalByRefObject m_target;
        private static object syncRoot = new object();

        public LazyLoadableSink(MarshalByRefObject target, IMessageSink nextSink)
        {
            lock (syncRoot)
            {
                m_target = target;
                m_nextSink = nextSink;
            }
        }

        public IMessage SyncProcessMessage(IMessage msg)
        {
            IMethodReturnMessage returnedMessage;
            HandleMessage(msg, false, out returnedMessage);
            return returnedMessage;
        }

        public IMessageCtrl AsyncProcessMessage(IMessage msg, IMessageSink replySink)
        {
            IMethodReturnMessage returnedMessage;
            HandleMessage(msg, true, out returnedMessage);
            return m_nextSink.AsyncProcessMessage(msg, replySink);
        }

        public IMessageSink NextSink
        {
            get { return m_nextSink; }
        }

        /// <summary>
        /// 处理消息
        /// </summary>
        /// <param name="msg"></param>
        /// <param name="IsAsync"></param>
        /// <param name="returnedMessage"></param>
        private void HandleMessage(IMessage msg, bool IsAsync, out IMethodReturnMessage returnedMessage)
        {
            returnedMessage = null;
            if (!IsAsync)
            {
                if (msg is IMethodCallMessage)
                {
                    Type entityType = m_target.GetType();
                    IMethodCallMessage mcm = (IMethodCallMessage)msg;

                    bool isFill = (bool)entityType.GetProperty("InnerIsFill", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(m_target, null);

                    //判断是否获取属性或字段或是调用GetValue方法
                    bool isProperty = !isFill && ((mcm.MethodName.Length > 4 &&
                       mcm.MethodName.Substring(0, 4) == "get_" && mcm.MethodName != "get_InnerIsFill" &&
                       mcm.MethodName != "get_InnerDataState") || mcm.MethodName == "FieldGetter" ||
                       mcm.MethodName == "GetValue");
                    object oldvalue = null;

                    MemberInfo minfo = null;
                    //属性名字段名
                    string propertyName = string.Empty;

                    if (isProperty)
                    {
                        //字段
                        if (mcm.MethodName == "FieldGetter")
                            propertyName = mcm.InArgs[1].ToString();
                        //GetValue方法
                        else if (mcm.MethodName == "GetValue")
                            propertyName = mcm.InArgs[0].ToString();
                        //属性
                        else
                            propertyName = mcm.MethodName.Replace("get_", "");

                        minfo = Utility.GetMember(m_target.GetType(), propertyName);
                        if (minfo == null)
                            isProperty = false;
                        //判断是否子实体集、引用实体、引用属性
                        else if (!minfo.IsDefined(typeof(SubEntityListAttribute), true) &&
                            !minfo.IsDefined(typeof(ReferenceEntityAttribute), true) &&
                            !minfo.IsDefined(typeof(ReferencePropertyAttribute), true))
                            isProperty = false;

                        if (isProperty)
                            oldvalue = Utility.GetMemberValue(m_target, minfo, propertyName);

                        //值为空时才读取数据库
                        if (isProperty && oldvalue == null)
                        {
                            //取出缓存的操作对象
                            string key = DataCacheKeyManager.GetEntityInnerData(entityType);
                            object innerData = InnerCache<object[]>.Get(key);

                            if (innerData != null)
                            {
                                //构造一下操作对象
                                object[] _innerData = (object[])innerData;
                                DataHelper data = (DataHelper)Activator.CreateInstance((Type)_innerData[0]);
                                if (string.IsNullOrEmpty(data.ConnectionString))
                                    data.ConnectionString = _innerData[1].ToString();

                                OperationArgs operArgs = new OperationArgs(data);
                                QueryBuilder query = new QueryBuilder(data.CreateParameters());
                                //子实体集
                                if (minfo.IsDefined(typeof(SubEntityListAttribute), true))
                                {
                                    SubEntityListAttribute keyAttribute = DataMappingManager.GetSubEntityListKey(entityType, propertyName);
                                    if (keyAttribute != null)
                                    {
                                        IDataEntityList list = (IDataEntityList)Activator.CreateInstance(keyAttribute.EntityListType);
                                        Type refentityType = list.ModelType;
                                        //取主键值
                                        object value = ((DataEntity)m_target).GetValue(keyAttribute.PrimaryKey);
                                        if (value != null)
                                        {
                                            //关联关系
                                            query.Append(QueryCompare.Equal, keyAttribute.ForeignKey, value);
                                            if (!string.IsNullOrEmpty(keyAttribute.Condition))
                                            {
                                                query.Append(QueryRelation.And, keyAttribute.Condition);
                                            }
                                            //查询实体集
                                            list = SelectOperator.Select(operArgs, refentityType, query, null, null);
                                            returnedMessage = new ReturnMessage(list, null, 0, null, mcm);
                                            ((DataEntity)m_target).SetValue(propertyName, returnedMessage.ReturnValue);
                                        }
                                    }
                                }
                                //引用实体
                                else if (minfo.IsDefined(typeof(ReferenceEntityAttribute), true))
                                {
                                    ReferenceEntityAttribute keyAttribute = DataMappingManager.GetReferenceEntityKey(entityType, propertyName);
                                    //取主键值
                                    object value = ((DataEntity)m_target).GetValue(keyAttribute.ForeignKey);
                                    if (value != null)
                                    {
                                        //关联关系
                                        query.Append(QueryCompare.Equal, keyAttribute.PrimaryKey, value);
                                        object result = GetOperator.Get(operArgs, keyAttribute.ReferenceType, query, null, null);
                                        returnedMessage = new ReturnMessage(result, null, 0, null, mcm);
                                        ((DataEntity)m_target).SetValue(propertyName, returnedMessage.ReturnValue);
                                    }
                                }
                                //引用属性
                                else if (minfo.IsDefined(typeof(ReferencePropertyAttribute), true))
                                {
                                    ReferencePropertyAttribute keyAttribute = DataMappingManager.GetReferencePropertyKey(entityType, propertyName);
                                    //取主键值
                                    object value = ((DataEntity)m_target).GetValue(keyAttribute.ForeignKey);
                                    if (value != null)
                                    {
                                        //关联关系
                                        query.Append(QueryCompare.Equal, keyAttribute.PrimaryKey, value);
                                        DataEntity entity1 = GetOperator.Get(operArgs, keyAttribute.ReferenceType, query, null, null);
                                        if (entity1 != null)
                                        {
                                            object result = entity1.GetValue((keyAttribute as ReferencePropertyAttribute).ReferencePropertyName);
                                            returnedMessage = new ReturnMessage(result, null, 0, null, mcm);
                                            ((DataEntity)m_target).SetValue((keyAttribute as IKeyAttribute).Property, result);
                                        }
                                    }
                                }
                                data.Dispose();
                            }
                        }
                    }
                }
                if (returnedMessage == null)
                    returnedMessage = (IMethodReturnMessage)m_nextSink.SyncProcessMessage(msg);
            }
            else
            {
                returnedMessage = null;
            }
        }

    }
}

      注意，innerData是在实体集加载的时候缓存的一个操作类型及连接串，以便在这里创建操作实体来进行数据读取。
      遗憾的是，对于Field目前没有能够加载出来。


      应用这两个AOP后的模型类没有太多的改动：

Code
    /// <summary>
    /// 公司类别模型类
    /// </summary>
    [Serializable]
    [DataTable("TCompanyType")]
    [LazyLoadable]
    [EntityListUpdatable]
    public class TCompanyType : DataEntity
    {
        
        /// <summary>
        /// 编号
        /// </summary>
        [DataColumn]
        [PrimaryKey(true)]
        public int Id;

        /// <summary>
        /// 名称
        /// </summary>
        [DataColumn]
        public string Name;

        /// <summary>
        /// 基本类别
        /// </summary>
        [DataColumn]
        public BaseType BaseType;

        /// <summary>
        /// 公司编号
        /// </summary>
        [DataColumn]
        public int CompanyId;

        /// <summary>
        /// 是否已删
        /// </summary>
        [DataColumn]
        public bool IsDelete;

        /// <summary>
        /// 上级编号
        /// </summary>
        [DataColumn]
        [ForeignKey(OperationTypes.Delete, typeof(TCompanyType), "Id")]
        public int ParentId;

        /// <summary>
        /// 子类个数
        /// </summary>
        [DataColumn]
        public int ChildCount;

        /// <summary>
        /// 排序
        /// </summary>
        [DataColumn]
        public int Sort;

        TCompanies m_Companies = null;
        /// <summary>
        /// 该类别下的所有公司
        /// </summary>
        [SubEntityList(OperationTypes.All, "ID", "CompanyTypeId")]
        public TCompanies Companies
        {
            get
            {
                return m_Companies;
            }
            set { m_Companies = value; }
        }

        TCompanyTypes m_SubCompanyTypes = null;

        /// <summary>
        /// 所有子类别
        /// </summary>
        [SubEntityList(OperationTypes.All, "ID", "ParentId")]
        public TCompanyTypes SubCompanyTypes
        {
            get
            {
                return m_SubCompanyTypes;
            }
            set { m_SubCompanyTypes = value; }
        }

    }

前台调用代码没有改变：

Code
        private void btnCascadeQuery_Click(object sender, EventArgs e)
        {
            //级联查询
            try
            {
                ATCompanyType da = new ATCompanyType();
                da.AccessOptions = AccessOptions.Defined;
                //排除引用实体属性
                da.PropertyFilter = null;
                //列出分类
                ListSubType(da.Select("ParentId=0"));
                da.Dispose();
            }
            catch (System.Exception e1)
            {
                ShowErrorMessage(e1.Message);
            }
        }

        //列出子分类
        private void ListSubType(TCompanyTypes list)
        {
            if (list == null) return;
            foreach(TCompanyType type in list)
            {
                //分类名称
                ShowMessage("类别名称:" + type.Name);
                //该分类下的公司
                ListSubCompany(type.Companies);
                //该分类下的子类
                ListSubType(type.SubCompanyTypes);
            }
        }

        //列出分类公司下面的子公司
        private void ListSubCompany(TCompanies companies)
        {
            if (companies == null) return;
            foreach (TCompany company in companies)
            {
                ShowMessage("公司名称:" + company.Name);
                ListSubCompany(company.SubCompanies);
            }
        }

      总结：使用继承ContextBoundObject感觉不爽，数据在经过这么多的Sink后，性能必定有所损耗，但配上分页，我想这样的不足可以有所弥补。

      声明：不要死里的盯着上面的代码，什么类不存在，我发这个的目的是阐述里面思想。