DDD~基础设施层
最近被ＤＤＤ吸引了阿，在这里感谢一下小佟，呵呵，领域驱动设计是个不错的东西，帮助我们把问题清晰化，这候对于复杂业务逻辑是很重要的，今天这一讲主要说一下ＤＤＤ中的基础设施层（Infrastructure）是如何被我实现的。
Infrastructure Layer：主要功能是对领域模块进行持久化的，在这个层中你需要把领域对象序列化到指定的元件中，可能是数据库，文件或者内存对象，当然它也要提供从物理元件取出数据到领域模型的功能，这是对应的。
目前的ＤＤＤ项目结果如下
对于Infrastructure这个层我不去定义接口而是让它去实现Domain层的接口，即一切从领域出发，而Infrastructure只负责具体的数据持久化工作，下面我们主要介绍一下IRepository.cs和IExtensionRepository.cs在Infrastructure层是如何被实现的。
与传统ＤＡＴＡ层的区别
一 传统Data层定义接口，为数据为导向，而不是以业务为导。
二 将Repository的方法中添加了领域规约，使它Infrastructure更有目的的去实现。
引入工作单元，使多方法形式一个事务的概念
IUnitOfWork接口也是在domain层实现的，不过在这里我们也介绍一下它的代码
public interface IUnitOfWork { /// <summary> /// 将操作提交到数据库， /// </summary> void Save(); /// <summary> /// 是否需要显示进行提交（save()） /// 默认为false，即在repository方法中自动完成提交，值为true时，表示需要显示调用save()方法 /// </summary> /// <returns></returns> bool IsExplicitSubmit { get; set; } }
工作单元会有保存save操作和是否显示提交的属性，开发人员可以根据业务情况去选择IsExplicitSubmit的状态，默认是自动提交，如果希望多个方法统一一次提
交，可以将IsExplicitSubmit设为true，然后手动进行save()，这是有助于提升程序性能的。
Infrastructure层的核心代码
public class DbContextRepository<TEntity> : IExtensionRepository<TEntity> where TEntity : class { #region Constructors public DbContextRepository(IUnitOfWork db, Action<string> logger) { iUnitWork = db; _Db = (DbContext)db; Logger = logger; ((IObjectContextAdapter)_Db).ObjectContext.CommandTimeout = 0; } public DbContextRepository(IUnitOfWork db) : this(db, null) { } #endregion #region Properties /// <summary> /// 数据上下文 /// </summary> protected DbContext _Db { get; private set; } /// <summary> /// 工作单元上下文,子类可以直接使用它 /// </summary> protected IUnitOfWork iUnitWork { get; set; } /// <summary> /// Action委托事例，在派生类可以操作它 /// </summary> protected Action<string> Logger { get; private set; } /// <summary> /// 得到上下文中表对象的所有记录数 /// 当数据表记录在千万以上时，select count(1) from table /// 的速度会受到影响，所以扩展一个方法解决这个问题 /// </summary> /// <param name="queryable"></param> /// <param name="db"></param> /// <returns></returns> public int RecordCount { get { return Convert.ToInt32(_Db.Database.SqlQuery<long>( "SELECT ROWCNT FROM SYSINDEXES WHERE ID=OBJECT_ID('" + typeof(TEntity).Name + "') AND INDID<2").First()); } } #endregion #region Fields /// <summary> /// 数据总数 /// </summary> int DataTotalCount = 0; /// <summary> /// 数据总页数 /// </summary> int DataTotalPages = 0; /// <summary> /// 数据页面大小（每次向数据库提交的记录数） /// </summary> int DataPageSize = 10000; #endregion #region IRepository<T> 成员 public virtual void Insert(TEntity item) { OnBeforeSaved(new SavedEventArgs(item, SaveAction.Insert)); _Db.Entry<TEntity>(item); _Db.Set<TEntity>().Add(item); this.SaveChanges(); OnAfterSaved(new SavedEventArgs(item, SaveAction.Insert)); } public virtual void Delete(TEntity item) { OnBeforeSaved(new SavedEventArgs(item, SaveAction.Delete)); _Db.Set<TEntity>().Attach(item); _Db.Set<TEntity>().Remove(item); this.SaveChanges(); OnAfterSaved(new SavedEventArgs(item, SaveAction.Delete)); } public virtual void Update(TEntity item) { OnBeforeSaved(new SavedEventArgs(item, SaveAction.Update)); _Db.Set<TEntity>().Attach(item); _Db.Entry(item).State = EntityState.Modified; this.SaveChanges(); OnAfterSaved(new SavedEventArgs(item, SaveAction.Update)); } public IQueryable<TEntity> GetModel() { return _Db.Set<TEntity>().AsNoTracking();//对象无法自动添加到上下文中，因为它是使用 NoTracking 合并选项检索的。请在定义此关系之前，将该实体显式附加到 ObjectContext。 // return _Db.Set<TEntity>(); } #endregion #region IExtensionRepository<T> 成员 public virtual void Insert(IEnumerable<TEntity> item) { item.ToList().ForEach(i => { _Db.Entry<TEntity>(i); _Db.Set<TEntity>().Add(i); }); this.SaveChanges(); } public virtual void Delete(IEnumerable<TEntity> item) { item.ToList().ForEach(i => { _Db.Set<TEntity>().Attach(i); _Db.Set<TEntity>().Remove(i); }); this.SaveChanges(); } public virtual void Update(IEnumerable<TEntity> item) { item.ToList().ForEach(i => { _Db.Set<TEntity>().Attach(i); _Db.Entry(i).State = EntityState.Modified; }); this.SaveChanges(); } public void Update<T>(Expression<Action<T>> entity) where T : class { T newEntity = typeof(T).GetConstructor(Type.EmptyTypes).Invoke(null) as T;//建立指定类型的实例 List<string> propertyNameList = new List<string>(); MemberInitExpression param = entity.Body as MemberInitExpression; foreach (var item in param.Bindings) { string propertyName = item.Member.Name; object propertyValue; var memberAssignment = item as MemberAssignment; if (memberAssignment.Expression.NodeType == ExpressionType.Constant) { propertyValue = (memberAssignment.Expression as ConstantExpression).Value; } else { propertyValue = Expression.Lambda(memberAssignment.Expression, null).Compile().DynamicInvoke(); } typeof(T).GetProperty(propertyName).SetValue(newEntity, propertyValue, null); propertyNameList.Add(propertyName); } _Db.Set<T>().Attach(newEntity); _Db.Configuration.ValidateOnSaveEnabled = false; var ObjectStateEntry = ((IObjectContextAdapter)_Db).ObjectContext.ObjectStateManager.GetObjectStateEntry(newEntity); propertyNameList.ForEach(x => ObjectStateEntry.SetModifiedProperty(x.Trim())); this.SaveChanges(); // ((IObjectContextAdapter)_Db).ObjectContext.Detach(newEntity); } public TEntity Find(params object[] id) { return _Db.Set<TEntity>().Find(id); } public IQueryable<TEntity> GetModel(ISpecification<TEntity> specification) { return GetModel().Where(specification.SatisfiedBy()); } public IQueryable<TEntity> GetModel(Expression<Func<TEntity, bool>> predicate) { return GetModel().Where(predicate); } public IQueryable<TEntity> GetModel<S>(Expression<Func<TEntity, S>> orderByExpression, bool asc) { Orderable<TEntity> order = new Orderable<TEntity>(this.GetModel()); if (asc) order.Asc(orderByExpression); else order.Desc(orderByExpression); return order.Queryable; } public TEntity Find(Expression<Func<TEntity, bool>> predicate) { return GetModel(predicate).FirstOrDefault(); } public TEntity Find(ISpecification<TEntity> specification) { return GetModel(specification).FirstOrDefault(); } public void BulkInsert(IEnumerable<TEntity> item) { DataPageProcess(item, (currentItems) => { ((IObjectContextAdapter)_Db).ObjectContext.CommandTimeout = 0;//永不超时 _Db.Database.ExecuteSqlCommand(DoSQL(currentItems, SQLType.Insert)); }); } public void BulkDelete(IEnumerable<TEntity> item) { DataPageProcess(item, (currentItems) => { ((IObjectContextAdapter)_Db).ObjectContext.CommandTimeout = 0;//永不超时 _Db.Database.ExecuteSqlCommand(DoSQL(currentItems, SQLType.Delete)); }); } public void BulkUpdate(IEnumerable<TEntity> item, params string[] fieldParams) { DataPageProcess(item, (currentItems) => { ((IObjectContextAdapter)_Db).ObjectContext.CommandTimeout = 0;//永不超时 _Db.Database.ExecuteSqlCommand(DoSQL(currentItems, SQLType.Update, fieldParams)); }); } public void BulkUpdate(IEnumerable<Expression<Action<TEntity>>> expressionList) { DataPageProcess(expressionList, (currentItems) => { StringBuilder sqlstr = new StringBuilder(); currentItems.ToList().ForEach(i => { Tuple<string, object[]> sql = CreateUpdateSQL(i); sqlstr.AppendFormat(sql.Item1, sql.Item2); }); ((IObjectContextAdapter)_Db).ObjectContext.CommandTimeout = 0;//永不超时 _Db.Database.ExecuteSqlCommand(sqlstr.ToString()); }); } public event Action<SavedEventArgs> AfterSaved; public event Action<SavedEventArgs> BeforeSaved; #endregion #region Protected Methods /// <summary> /// 根据工作单元的IsUnitOfWork的属性，去判断是否提交到数据库 /// 一般地，在多个repository类型进行组合时，这个IsUnitOfWork都会设为true，即不马上提交， /// 而对于单个repository操作来说，它的值不需要设置，使用默认的false，将直接提交到数据库，这也保证了操作的原子性。 /// </summary> protected void SaveChanges() { try { if (!iUnitWork.IsExplicitSubmit)// if (iUnitWork.IsUnitOfWork ^ true) iUnitWork.Save(); } catch (System.Data.Entity.Validation.DbEntityValidationException dbEx) { if (Logger == null) throw dbEx; Logger(dbEx.Message); } catch (Exception ex) { if (Logger == null)//如果没有定义日志功能，就把异常抛出来吧 throw ex; Logger(ex.Message); } } /// <summary> /// 计数更新,与SaveChange()是两个SQL链接，走分布式事务 /// 子类可以根据自己的逻辑，去复写 /// tableName:表名 /// param:索引0为主键名，1表主键值，2为要计数的字段，3为增量 /// </summary> /// <param name="tableName">表名</param> /// <param name="param">参数列表，索引0为主键名，1表主键值，2为要计数的字段，3为增量</param> protected virtual void UpdateForCount(string tableName, params object[] param) { string sql = "UPDATE [" + tableName + "] SET [{2}]=ISNULL([{2}],0)+{3} WHERE [{0}]={1}"; List<object> listParasm = new List<object> { param[0], param[1], param[2], param[3], }; _Db.Database.ExecuteSqlCommand(string.Format(sql, listParasm.ToArray())); } #endregion #region Virtual Methods /// <summary> /// Called after data saved /// </summary> /// <param name="sender">The sender.</param> /// <param name="action">The action.</param> protected virtual void OnAfterSaved(SavedEventArgs e) { if (AfterSaved != null) { AfterSaved(e); } } /// <summary> /// Called before saved /// </summary> /// <param name="sender">The sender.</param> /// <param name="action">The action.</param> protected virtual void OnBeforeSaved(SavedEventArgs e) { if (BeforeSaved != null) { BeforeSaved(e); } } #endregion #region Private Methods /// <summary> /// 分页进行数据提交的逻辑 /// </summary> /// <param name="item">原列表</param> /// <param name="method">处理方法</param> /// <param name="currentItem">要进行处理的新列表</param> private void DataPageProcess( IEnumerable<TEntity> item, Action<IEnumerable<TEntity>> method) { if (item != null && item.Count() > 0) { DataTotalCount = item.Count(); this.DataTotalPages = item.Count() / DataPageSize; if (DataTotalCount % DataPageSize > 0) DataTotalPages += 1; for (int pageIndex = 1; pageIndex <= DataTotalPages; pageIndex++) { var currentItems = item.Skip((pageIndex - 1) * DataPageSize).Take(DataPageSize).ToList(); method(currentItems); } } } private void DataPageProcess( IEnumerable<Expression<Action<TEntity>>> item, Action<IEnumerable<Expression<Action<TEntity>>>> method) { if (item != null && item.Count() > 0) { DataTotalCount = item.Count(); this.DataTotalPages = item.Count() / DataPageSize; if (DataTotalCount % DataPageSize > 0) DataTotalPages += 1; for (int pageIndex = 1; pageIndex <= DataTotalPages; pageIndex++) { var currentItems = item.Skip((pageIndex - 1) * DataPageSize).Take(DataPageSize).ToList(); method(currentItems); } } } private static string GetEqualStatment(string fieldName, int paramId, Type pkType) { if (pkType.IsValueType) return string.Format("{0} = {1}", fieldName, GetParamTag(paramId)); return string.Format("{0} = '{1}'", fieldName, GetParamTag(paramId)); } private static string GetParamTag(int paramId) { return "{" + paramId + "}"; } /// <summary> /// 得到实体键EntityKey /// </summary> /// <typeparam name="TEntity"></typeparam> /// <returns></returns> protected ReadOnlyMetadataCollection<EdmMember> GetPrimaryKey() { EntitySetBase primaryKey = ((IObjectContextAdapter)_Db).ObjectContext.GetEntitySet(typeof(TEntity)); ReadOnlyMetadataCollection<EdmMember> arr = primaryKey.ElementType.KeyMembers; return arr; } /// <summary> /// 构建Update语句串 /// 注意：如果本方法过滤了int,decimal类型更新为０的列，如果希望更新它们需要指定FieldParams参数 /// </summary> /// <param name="entity">实体列表</param> /// <param name="fieldParams">要更新的字段</param> /// <returns></returns> private Tuple<string, object[]> CreateUpdateSQL(Expression<Action<TEntity>> expression) { TEntity entity = typeof(TEntity).GetConstructor(Type.EmptyTypes).Invoke(null) as TEntity;//建立指定类型的实例 List<string> propertyNameList = new List<string>(); MemberInitExpression param = expression.Body as MemberInitExpression; foreach (var item in param.Bindings) { string propertyName = item.Member.Name; object propertyValue; var memberAssignment = item as MemberAssignment; if (memberAssignment.Expression.NodeType == ExpressionType.Constant) { propertyValue = (memberAssignment.Expression as ConstantExpression).Value; } else { propertyValue = Expression.Lambda(memberAssignment.Expression, null).Compile().DynamicInvoke(); } typeof(TEntity).GetProperty(propertyName).SetValue(entity, propertyValue, null); propertyNameList.Add(propertyName); } return CreateUpdateSQL(entity, propertyNameList.ToArray()); } /// <summary> /// 构建Update语句串 /// 注意：如果本方法过滤了int,decimal类型更新为０的列，如果希望更新它们需要指定FieldParams参数 /// </summary> /// <param name="entity">实体列表</param> /// <param name="fieldParams">要更新的字段</param> /// <returns></returns> private Tuple<string, object[]> CreateUpdateSQL(TEntity entity, params string[] fieldParams) { if (entity == null) throw new ArgumentException("The database entity can not be null."); List<string> pkList = GetPrimaryKey().Select(i => i.Name).ToList(); Type entityType = entity.GetType(); List<PropertyInfo> tableFields = new List<PropertyInfo>(); if (fieldParams != null && fieldParams.Count() > 0) { tableFields = entityType.GetProperties().Where(i => fieldParams.Contains(i.Name, new StringComparisonIgnoreCase())).ToList(); } else { tableFields = entityType.GetProperties().Where(i => !pkList.Contains(i.Name) && i.GetValue(entity, null) != null && !(i.PropertyType == typeof(ValueType) && Convert.ToInt64(i.GetValue(entity, null)) == 0) && !(i.PropertyType == typeof(DateTime) && Convert.ToDateTime(i.GetValue(entity, null)) == DateTime.MinValue) && i.PropertyType != typeof(EntityState) && !(i.GetCustomAttributes(false).Length > 0 && i.GetCustomAttributes(false).Where(j => j.GetType() == typeof(NavigationAttribute)) != null)//过滤导航属性 && (i.PropertyType.IsValueType || i.PropertyType == typeof(string)) ).ToList(); } //过滤主键，航行属性，状态属性等 if (pkList == null || pkList.Count == 0) throw new ArgumentException("The Table entity have not a primary key."); List<object> arguments = new List<object>(); StringBuilder builder = new StringBuilder(); foreach (var change in tableFields) { if (pkList.Contains(change.Name)) continue; if (arguments.Count != 0) builder.Append(", "); builder.Append(change.Name + " = {" + arguments.Count + "}"); if (change.PropertyType == typeof(string) || change.PropertyType == typeof(DateTime) || change.PropertyType == typeof(Nullable<DateTime>)) arguments.Add("'" + change.GetValue(entity, null).ToString().Replace("'", "char(39)") + "'"); else arguments.Add(change.GetValue(entity, null)); } if (builder.Length == 0) throw new Exception("没有任何属性进行更新"); builder.Insert(0, " UPDATE " + string.Format("[{0}]", entityType.Name) + " SET "); builder.Append(" WHERE "); bool firstPrimaryKey = true; foreach (var primaryField in pkList) { if (firstPrimaryKey) firstPrimaryKey = false; else builder.Append(" AND "); object val = entityType.GetProperty(primaryField).GetValue(entity, null); Type pkType = entityType.GetProperty(primaryField).GetType(); builder.Append(GetEqualStatment(primaryField, arguments.Count, pkType)); arguments.Add(val); } return new Tuple<string, object[]>(builder.ToString(), arguments.ToArray()); } /// <summary> /// 构建Delete语句串 /// </summary> /// <typeparam name="TEntity"></typeparam> /// <param name="entity"></param> /// <returns></returns> private Tuple<string, object[]> CreateDeleteSQL(TEntity entity) { if (entity == null) throw new ArgumentException("The database entity can not be null."); Type entityType = entity.GetType(); List<string> pkList = GetPrimaryKey().Select(i => i.Name).ToList(); if (pkList == null || pkList.Count == 0) throw new ArgumentException("The Table entity have not a primary key."); List<object> arguments = new List<object>(); StringBuilder builder = new StringBuilder(); builder.Append(" Delete from " + string.Format("[{0}]", entityType.Name)); builder.Append(" WHERE "); bool firstPrimaryKey = true; foreach (var primaryField in pkList) { if (firstPrimaryKey) firstPrimaryKey = false; else builder.Append(" AND "); Type pkType = entityType.GetProperty(primaryField).GetType(); object val = entityType.GetProperty(primaryField).GetValue(entity, null); builder.Append(GetEqualStatment(primaryField, arguments.Count, pkType)); arguments.Add(val); } return new Tuple<string, object[]>(builder.ToString(), arguments.ToArray()); } /// <summary> /// 构建Insert语句串 /// 主键为自增时，如果主键值为0，我们将主键插入到SQL串中 /// </summary> /// <typeparam name="TEntity"></typeparam> /// <param name="entity"></param> /// <returns></returns> private Tuple<string, object[]> CreateInsertSQL(TEntity entity) { if (entity == null) throw new ArgumentException("The database entity can not be null."); Type entityType = entity.GetType(); var table = entityType.GetProperties().Where(i => i.PropertyType != typeof(EntityKey) && i.PropertyType != typeof(EntityState) && i.Name != "IsValid" && i.GetValue(entity, null) != null && !(i.GetCustomAttributes(false).Length > 0 && i.GetCustomAttributes(false).Where(j => j.GetType() == typeof(NavigationAttribute)) != null) && (i.PropertyType.IsValueType || i.PropertyType == typeof(string))).ToArray();//过滤主键，航行属性，状态属性等 List<string> pkList = GetPrimaryKey().Select(i => i.Name).ToList(); List<object> arguments = new List<object>(); StringBuilder fieldbuilder = new StringBuilder(); StringBuilder valuebuilder = new StringBuilder(); fieldbuilder.Append(" INSERT INTO " + string.Format("[{0}]", entityType.Name) + " ("); foreach (var member in table) { if (pkList.Contains(member.Name) && Convert.ToString(member.GetValue(entity, null)) == "0") continue; object value = member.GetValue(entity, null); if (value != null) { if (arguments.Count != 0) { fieldbuilder.Append(", "); valuebuilder.Append(", "); } fieldbuilder.Append(member.Name); if (member.PropertyType == typeof(string) || member.PropertyType == typeof(DateTime) || member.PropertyType == typeof(Nullable<DateTime>) ) valuebuilder.Append("'{" + arguments.Count + "}'"); else valuebuilder.Append("{" + arguments.Count + "}"); if (value.GetType() == typeof(string)) value = value.ToString().Replace("'", "char(39)"); arguments.Add(value); } } fieldbuilder.Append(") Values ("); fieldbuilder.Append(valuebuilder.ToString()); fieldbuilder.Append(");"); return new Tuple<string, object[]>(fieldbuilder.ToString(), arguments.ToArray()); } /// <summary> /// /// <summary> /// 执行SQL，根据SQL操作的类型 /// </summary> /// <typeparam name="TEntity"></typeparam> /// <param name="list"></param> /// <param name="sqlType"></param> /// <returns></returns> /// </summary> /// <param name="list"></param> /// <param name="sqlType"></param> /// <returns></returns> private string DoSQL(IEnumerable<TEntity> list, SQLType sqlType) { return DoSQL(list, sqlType, null); } /// <summary> /// 执行SQL，根据SQL操作的类型 /// </summary> /// <typeparam name="TEntity"></typeparam> /// <param name="list"></param> /// <param name="sqlType"></param> /// <returns></returns> private string DoSQL(IEnumerable<TEntity> list, SQLType sqlType, params string[] fieldParams) { StringBuilder sqlstr = new StringBuilder(); switch (sqlType) { case SQLType.Insert: list.ToList().ForEach(i => { Tuple<string, object[]> sql = CreateInsertSQL(i); sqlstr.AppendFormat(sql.Item1, sql.Item2); }); break; case SQLType.Update: list.ToList().ForEach(i => { Tuple<string, object[]> sql = CreateUpdateSQL(i, fieldParams); sqlstr.AppendFormat(sql.Item1, sql.Item2); }); break; case SQLType.Delete: list.ToList().ForEach(i => { Tuple<string, object[]> sql = CreateDeleteSQL(i); sqlstr.AppendFormat(sql.Item1, sql.Item2); }); break; default: throw new ArgumentException("请输入正确的参数"); } return sqlstr.ToString(); } /// <summary> /// SQL操作类型 /// </summary> protected enum SQLType { /// <summary> /// 更新传入的实体代码去添加 /// </summary> Insert, /// <summary> /// 根据传入的实体列表去更新 /// </summary> Update, /// <summary> /// 根据传入的实体列表去删除 /// </summary> Delete, } #endregion }
下面看一下对于基础设施层所依赖的程序集
可以看到，它主要依赖于领域实体层与领域实体规约层。
OK，对于基础设施层的搭建就说到这，下回我们将说一下领域层的搭建。