AOP的兩個應用：實體集更新(DateEntityListUpdate)、延遲加載(LazyLoad)（下）
LazyLoadableSink類
//*******************************************************************
// 模塊:實現延遲載入的消息接收器
// 日期:2009-9-19 14:08:58
// 作者:Faib
// 版權:Copyright Faib Studio 2009
// 官網:http：//www.faib.net.cn
// 郵箱:[email protected]
// 備注:
//*******************************************************************
using System;
using System.Reflection;
using System.Runtime.Remoting.Messaging;
using FaibClass.Data.Operation;
namespace FaibClass.Data.Aspect
{
/// <summary>
/// 實現延遲載入的消息接收器。
/// </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>
/// 處理消息
/// </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);
//判斷是否獲取屬性或字段或是調用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;
//屬性名字段名
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();
//屬性
else
propertyName = mcm.MethodName.Replace("get_", "");
minfo = Utility.GetMember(m_target.GetType(), propertyName);
if (minfo == null)
isProperty = false;
//判斷是否子實體集、引用實體、引用屬性
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);
//值為空時才讀取數據庫
if (isProperty && oldvalue == null)
{
//取出緩存的操作對象
string key = DataCacheKeyManager.GetEntityInnerData(entityType);
object innerData = InnerCache<object[]>.Get(key);
if (innerData != null)
{
//構造一下操作對象
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());
//子實體集
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;
//取主鍵值
object value = ((DataEntity)m_target).GetValue(keyAttribute.PrimaryKey);
if (value != null)
{
//關聯關系
query.Append(QueryCompare.Equal, keyAttribute.ForeignKey, value);
if (!string.IsNullOrEmpty(keyAttribute.Condition))
{
query.Append(QueryRelation.And, keyAttribute.Condition);
}
//查詢實體集
list = SelectOperator.Select(operArgs, refentityType, query, null, null);
returnedMessage = new ReturnMessage(list, null, 0, null, mcm);
((DataEntity)m_target).SetValue(propertyName, returnedMessage.ReturnValue);
}
}
}
//引用實體
else if (minfo.IsDefined(typeof(ReferenceEntityAttribute), true))
{
ReferenceEntityAttribute keyAttribute = DataMappingManager.GetReferenceEntityKey(entityType, propertyName);
//取主鍵值
object value = ((DataEntity)m_target).GetValue(keyAttribute.ForeignKey);
if (value != null)
{
//關聯關系
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);
}
}
//引用屬性
else if (minfo.IsDefined(typeof(ReferencePropertyAttribute), true))
{
ReferencePropertyAttribute keyAttribute = DataMappingManager.GetReferencePropertyKey(entityType, propertyName);
//取主鍵值
object value = ((DataEntity)m_target).GetValue(keyAttribute.ForeignKey);
if (value != null)
{
//關聯關系
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是在實體集加載的時候緩存的一個操作類型及連接串，以便在這裡創建操作實體來進行數據讀取。
遺憾的是，對於Field目前沒有能夠加載出來。
應用這兩個AOP後的模型類沒有太多的改動：
/// <summary>
/// 公司類別模型類
/// </summary>
[Serializable]
[DataTable("TCompanyType")]
[LazyLoadable]
[EntityListUpdatable]
public class TCompanyType : DataEntity
{
/// <summary>
/// 編號
/// </summary>
[DataColumn]
[PrimaryKey(true)]
public int Id;
/// <summary>
/// 名稱
/// </summary>
[DataColumn]
public string Name;
/// <summary>
/// 基本類別
/// </summary>
[DataColumn]
public BaseType BaseType;
/// <summary>
/// 公司編號
/// </summary>
[DataColumn]
public int CompanyId;
/// <summary>
/// 是否已刪
/// </summary>
[DataColumn]
public bool IsDelete;
/// <summary>
/// 上級編號
/// </summary>
[DataColumn]
[ForeignKey(OperationTypes.Delete, typeof(TCompanyType), "Id")]
public int ParentId;
/// <summary>
/// 子類個數
/// </summary>
[DataColumn]
public int ChildCount;
/// <summary>
/// 排序
/// </summary>
[DataColumn]
public int Sort;
TCompanies m_Companies = null;
/// <summary>
/// 該類別下的所有公司
/// </summary>
[SubEntityList(OperationTypes.All, "ID", "CompanyTypeId")]
public TCompanies Companies
{
get
{
return m_Companies;
}
set { m_Companies = value; }
}
TCompanyTypes m_SubCompanyTypes = null;
/// <summary>
/// 所有子類別
/// </summary>
[SubEntityList(OperationTypes.All, "ID", "ParentId")]
public TCompanyTypes SubCompanyTypes
{
get
{
return m_SubCompanyTypes;
}
set { m_SubCompanyTypes = value; }
}
}
前台調用代碼沒有改變：
private void btnCascadeQuery_Click(object sender, EventArgs e)
{
//級聯查詢
try
{
ATCompanyType da = new ATCompanyType();
da.AccessOptions = AccessOptions.Defined;
//排除引用實體屬性
da.PropertyFilter = null;
//列出分類
ListSubType(da.Select("ParentId=0"));
da.Dispose();
}
catch (System.Exception e1)
{
ShowErrorMessage(e1.Message);
}
}
//列出子分類
private void ListSubType(TCompanyTypes list)
{
if (list == null) return;
foreach(TCompanyType type in list)
{
//分類名稱
ShowMessage("類別名稱:" + type.Name);
//該分類下的公司
ListSubCompany(type.Companies);
//該分類下的子類
ListSubType(type.SubCompanyTypes);
}
}
//列出分類公司下面的子公司
private void ListSubCompany(TCompanies companies)
{
if (companies == null) return;
foreach (TCompany company in companies)
{
ShowMessage("公司名稱:" + company.Name);
ListSubCompany(company.SubCompanies);
}
}
總結：使用繼承ContextBoundObject感覺不爽，數據在經過這麼多的Sink後，性能必定有所損耗，但配上分頁，我想這樣的不足可以有所彌補。
聲明：不要死裡的盯著上面的代碼，什麼類不存在，我發這個的目的是闡述裡面思想。
