数据存储层在项目Ninesky.DataLibrary中实现，整个项目只有一个类Repository。

Repository中实现增删改查询等方法供业务逻辑层调用，主要功能如下图：

具体步骤

一、添加实体框架的引用

1、打开解决方案，选择项目Ninesky.DataLibrary，在引用上右键，选择管理NuGet程序包。

在NuGet包管理器中的浏览标签中点击EntityFramework，点击右侧栏的安装按钮。

在搜索框输入EntityFramework.zh-Hans,安装假体中文资源包。

二、实现数据仓储类

打开解决方案，选择项目Ninesky.DataLibrary，将Class1.cs重命名为Repository.cs，在文档头添加using System.Data.Entity;将类名重命名为public class Repository。改为public class Repository<T> where T :class

1、DbContext属性

在Repository类中添加如下代码 public DbContext DbContext { get; set; }

2、构造函数

为类中添加够高函数，可以直接传递DbContex。

public Repository() { } public Repository(DbContext dbContext) { DbContext = dbContext; }

3、查找实体方法Find

Find有一个重载。两个方法分别可以根据ID和根据lamdba表达式查找实体。

/// <summary> /// 查找实体 /// </summary> /// <param name="ID">实体主键值</param> /// <returns></returns> public T Find(int ID) { return DbContext.Set<T>().Find(ID); } /// <summary> /// 查找实体 /// </summary> /// <param name="where">查询Lambda表达式</param> /// <returns></returns> public T Find(Expression<Func<T,bool>> where) { return DbContext.Set<T>().SingleOrDefault(where); }

4、查找实体列表方法FindList

根据需要FindList进行多次重载

/// <summary> /// 查找实体列表 /// </summary> /// <returns></returns> public IQueryable<T> FindList() { return DbContext.Set<T>(); } /// <summary> /// 查找实体列表 /// </summary> /// <typeparam name="TKey">排序建类型</typeparam> /// <param name="order">排序表达式</param> /// <param name="asc">是否正序</param> /// <returns></returns> public IQueryable<T> FindList<TKey>(Expression<Func<T, TKey>> order, bool asc) { return asc ? DbContext.Set<T>().OrderBy(order) : DbContext.Set<T>().OrderByDescending(order); } /// <summary> /// 查找实体列表 /// </summary> /// <typeparam name="TKey">排序键类型</typeparam> /// <param name="order">排序键</param> /// <param name="asc">是否正序</param> /// <param name="number">获取的记录数量</param> /// <returns></returns> public IQueryable<T> FindList<TKey>(Expression<Func<T, TKey>> order, bool asc,int number) { return asc ? DbContext.Set<T>().OrderBy(order).Take(number) : DbContext.Set<T>().OrderByDescending(order).Take(number); } /// <summary> /// 查找实体列表 /// </summary> /// <param name="where">查询Lambda表达式</param> /// <returns></returns> public IQueryable<T> FindList(Expression<Func<T, bool>> where) { return DbContext.Set<T>().Where(where); } /// <summary> /// 查找实体列表 /// </summary> /// <param name="where">查询Lambda表达式</param> /// <param name="number">获取的记录数量</param> /// <returns></returns> public IQueryable<T> FindList(Expression<Func<T, bool>> where, int number) { return DbContext.Set<T>().Where(where).Take(number); } /// <summary> /// 查找实体列表 /// </summary> /// <typeparam name="TKey">排序键类型</typeparam> /// <param name="where">查询Lambda表达式</param> /// <param name="order">排序键</param> /// <param name="asc">是否正序</param> /// <returns></returns> public IQueryable<T> FindList<TKey>(Expression<Func<T, bool>> where, Expression<Func<T, TKey>> order, bool asc) { return asc ? DbContext.Set<T>().Where(where).OrderBy(order) : DbContext.Set<T>().Where(where).OrderByDescending(order); } /// <summary> /// 查找实体列表 /// </summary> /// <typeparam name="TKey">排序键类型</typeparam> /// <param name="where">查询Lambda表达式</param> /// <param name="order">排序键</param> /// <param name="asc">是否正序</param> /// <param name="number">获取的记录数量</param> /// <returns></returns> public IQueryable<T> FindList<TKey>(Expression<Func<T, bool>> where, Expression<Func<T, TKey>> order, bool asc, int number) { return asc ? DbContext.Set<T>().Where(where).OrderBy(order).Take(number) : DbContext.Set<T>().Where(where).OrderByDescending(order).Take(number); }

5、查找实体分页列表方法FindPageList

根据需要FindPageList进行多次重载

/// <summary> /// 查找分页列表 /// </summary> /// <param name="pageSize">每页记录数。必须大于1</param> /// <param name="pageIndex">页码。首页从1开始，页码必须大于1</param> /// <param name="totalNumber">总记录数</param> /// <returns></returns> public IQueryable<T> FindPageList(int pageSize, int pageIndex, out int totalNumber) { if (pageIndex < 1) pageIndex = 1; if (pageSize < 1) pageSize = 10; IQueryable<T> _list = DbContext.Set<T>(); totalNumber = _list.Count(); return _list.Skip((pageIndex - 1) * pageIndex).Take(pageSize); } /// <summary> /// 查找分页列表 /// </summary> /// <param name="pageSize">每页记录数。必须大于1</param> /// <param name="pageIndex">页码。首页从1开始，页码必须大于1</param> /// <param name="totalNumber">总记录数</param> /// <param name="order">排序键</param> /// <param name="asc">是否正序</param> /// <returns></returns> public IQueryable<T> FindPageList<TKey>(int pageSize, int pageIndex, out int totalNumber, Expression<Func<T, TKey>> order, bool asc) { if (pageIndex < 1) pageIndex = 1; if (pageSize < 1) pageSize = 10; IQueryable<T> _list = DbContext.Set<T>(); _list = asc ? _list.OrderBy(order) : _list.OrderByDescending(order); totalNumber = _list.Count(); return _list.Skip((pageIndex - 1) * pageIndex).Take(pageSize); } /// <summary> /// 查找分页列表 /// </summary> /// <param name="pageSize">每页记录数。必须大于1</param> /// <param name="pageIndex">页码。首页从1开始，页码必须大于1</param> /// <param name="totalNumber">总记录数</param> /// <param name="where">查询表达式</param> public IQueryable<T> FindPageList(int pageSize, int pageIndex, out int totalNumber, Expression<Func<T, bool>> where) { if (pageIndex < 1) pageIndex = 1; if (pageSize < 1) pageSize = 10; IQueryable<T> _list = DbContext.Set<T>().Where(where); totalNumber = _list.Count(); return _list.Skip((pageIndex - 1) * pageIndex).Take(pageSize); } /// <summary> /// 查找分页列表 /// </summary> /// <param name="pageSize">每页记录数。必须大于1</param> /// <param name="pageIndex">页码。首页从1开始，页码必须大于1</param> /// <param name="totalNumber">总记录数</param> /// <param name="where">查询表达式</param> /// <param name="order">排序键</param> /// <param name="asc">是否正序</param> public IQueryable<T> FindPageList<TKey>(int pageSize, int pageIndex, out int totalNumber, Expression<Func<T, bool>> where, Expression<Func<T, TKey>> order, bool asc) { if (pageIndex < 1) pageIndex = 1; if (pageSize < 1) pageSize = 10; IQueryable<T> _list = DbContext.Set<T>().Where(where); _list = asc ? _list.OrderBy(order) : _list.OrderByDescending(order); totalNumber = _list.Count(); return _list.Skip((pageIndex - 1) * pageIndex).Take(pageSize); }

6、添加实体方法Add

Add 方法有一个重载，重载方法可以选择是否立即保存

/// <summary> /// 添加实体 /// </summary> /// <param name="entity">实体</param> /// <returns>受影响的对象的数目</returns> public int Add(T entity) { return Add(entity, true); } /// <summary> /// 添加实体 /// </summary> /// <param name="entity">实体</param> /// <param name="isSave">是否立即保存</param> /// <returns>在“isSave”为True时返回受影响的对象的数目，为False时直接返回0</returns> public int Add(T entity,bool isSave) { DbContext.Set<T>().Add(entity); return isSave ? DbContext.SaveChanges() : 0; }

7、更新实体方法Update

Updae 方法有一个重载，重载方法可以选择是否立即保存

#region Update /// <summary> /// 更新实体【立即保存】 /// </summary> /// <param name="entity">实体</param> /// <returns>在“isSave”为True时返回受影响的对象的数目，为False时直接返回0</returns> public int Update(T entity) { return Update(entity, true); } /// <summary> /// 更新实体 /// </summary> /// <param name="entity">实体</param> /// <param name="isSave">是否立即保存</param> /// <returns>在“isSave”为True时返回受影响的对象的数目，为False时直接返回0</returns> public int Update(T entity, bool isSave) { DbContext.Set<T>().Attach(entity); DbContext.Entry<T>(entity).State = EntityState.Modified; return isSave ? DbContext.SaveChanges() : 0; }

8、删除实体方法Delete

Delete 方法有两个重载，一个是可以选择否立即保存，另一个是批量删除

/// <summary> /// 删除实体【立即保存】 /// </summary> /// <param name="entity">实体</param> /// <returns>受影响的对象的数目</returns> public int Delete(T entity) { return Delete(entity, true); } /// <summary> /// 删除实体 /// </summary> /// <param name="entity">实体</param> /// <param name="isSave">是否立即保存</param> /// <returns>在“isSave”为True时返回受影响的对象的数目，为False时直接返回0</returns> public int Delete(T entity,bool isSave) { DbContext.Set<T>().Remove(entity); return isSave ? DbContext.SaveChanges() : 0; } /// <summary> /// 批量删除实体 /// </summary> /// <param name="entities">实体集合</param> /// <returns>受影响的对象的数目</returns> public int Delete(IEnumerable<T> entities) { DbContext.Set<T>().RemoveRange(entities); return DbContext.SaveChanges(); }

9、统计记录数方法Count

Count 方法有一个重载，可以根据表达式进行统计

/// <summary> /// 记录数 /// </summary> /// <returns></returns> public int Count() { return DbContext.Set<T>().Count(); } /// <summary> /// 记录数 /// </summary> /// <param name="predicate">表达式</param> /// <returns></returns> public int Count(Expression<Func<T, bool>> predicate) { return DbContext.Set<T>().Count(predicate); }

10、是否存在

/// <summary> /// 记录是否存在 /// </summary> /// <param name="predicate">表达式</param> /// <returns></returns> public bool IsContains(Expression<Func<T, bool>> predicate) { return Count(predicate) > 0; }

11、保存到数据库

/// <summary> /// 保存数据【在Add、Upate、Delete未立即保存的情况下使用】 /// </summary> /// <returns>受影响的记录数</returns> public int Save() { return DbContext.SaveChanges(); }