【.Net设计模式系列】工作单元(Unit Of Work)模式 ( 二 )

时间：2016-02-16 23:18:14 阅读：373 评论：0 收藏：0 [点我收藏+]

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在上一篇博客【.Net设计模式系列】仓储(Repository)模式 ( 一 ) 中，通过各位兄台的评论中，可以看出在设计上还有很多的问题，在这里特别感谢 @横竖都溢 @ 浮云飞梦 2位兄台对博文中存在的问题给予指出，并提供出好的解决方案，同时也感谢其他园友的支持。欢迎各位园友对博文中出现的错误或者是设计误区给予指出，一方面防止“误人子弟”，另一方面则可以让大家共同成长。

对于上一篇博客，只是给大家提供了一种对于小型项目数据访问层的一种实现方式，通过Sql语句和传递参数来实现CRUD。并未达到真正意义上的解耦。特此在本篇继续完善。

理论介绍

在进行数据库添加、修改、删除时，为了保证事务的一致性，即操作要么全部成功，要么全部失败。例如银行A、B两个账户的转账业务。一方失败都会导致事务的不完整性，从而事务回滚。而工作单元模式可以跟踪事务，在操作完成时对事务进行统一提交。

理论参考：http://martinfowler.com/eaaCatalog/unitOfWork.html

具体实践

首先，讲解下设计思想：领域层通过相应的库实现泛型仓储接口来持久化聚合类，之后在抽象库中将对泛型仓储接口提供基础实现，并将对应的实体转化为SQl语句。这样领域层就不需要操作Sql语句即可完成CRUD操作，同时使用工作单元对事务进行统一提交。

1）定义仓储接口，包含基本的CRUD操作及其重载不同的查询

 1 public interface IRepository<T>
 2     {
 3         /// <summary>
 4         /// 插入对象
 5         /// </summary>
 6         /// <param name="entity"></param>
 7         int Insert(T entity);
 8 
 9         /// <summary>
10         /// 更新对象
11         /// </summary>
12         /// <param name="entity"></param>
13         /// <param name="predicate"></param>
14         int Update(T entity, Expression<Func<T, bool>> express);
15 
16         /// <summary>
17         /// 删除对象
18         /// </summary>
19         /// <param name="predicate"></param>
20         int Delete(Expression<Func<T, bool>> express = null);
21 
22         /// <summary>
23         /// 查询对象集合
24         /// </summary>
25         /// <param name="predicate"></param>
26         /// <returns></returns>
27         List<T> QueryAll(Expression<Func<T, bool>> express = null);
28 
29         /// <summary>
30         /// 查询对象集合
31         /// </summary>
32         /// <param name="index"></param>
33         /// <param name="pagesize"></param>
34         /// <param name="order"></param>
35         /// <param name="asc"></param>
36         /// <param name="express"></param>
37         /// <returns></returns>
38         List<T> QueryAll(int index,int pagesize,List<PropertySortCondition> orderFields, Expression<Func<T, bool>> express = null);
39 
40         /// <summary>
41         /// 查询对象集合
42         /// </summary>
43         /// <param name="type"></param>
44         /// <param name="predicate"></param>
45         /// <returns></returns>
46         List<object> QueryAll(Type type, Expression<Func<T, bool>> express = null);
47 
48         /// <summary>
49         /// 查询对象
50         /// </summary>
51         /// <param name="predicate"></param>
52         /// <returns></returns>
53         T Query(Expression<Func<T, bool>> express);
54 
55         /// <summary>
56         /// 查询数量
57         /// </summary>
58         /// <param name="predicate"></param>
59         /// <returns></returns>
60         object QueryCount(Expression<Func<T, bool>> express = null);
61     }

其次，对仓储接口提供基本实现，这里由于使用了Lambda表达式，所以就需要进行表达式树的解析。

  1  public abstract class BaseRepository<T> : IRepository<T>
  2         where T:class,new()
  3     {
  4         private IUnitOfWork unitOfWork;
  5 
  6         private IUnitOfWorkContext context;
  7 
  8         public BaseRepository(IUnitOfWork unitOfWork, IUnitOfWorkContext context)
  9         {
 10             this.unitOfWork = unitOfWork;
 11             this.context = context;
 12         }
 13 
 14         Lazy<ConditionBuilder> builder = new Lazy<ConditionBuilder>();
 15 
 16         public string tableName {
 17             get
 18             {
 19                 TableNameAttribute attr= (TableNameAttribute)typeof(T).GetCustomAttribute(typeof(TableNameAttribute));
 20                 return attr.Name; 
 21             }
 22         }
 23 
 24         /// <summary>
 25         /// 插入对象
 26         /// </summary>
 27         /// <param name="entity"></param>
 28         public virtual int Insert(T entity)
 29         {
 30             Func<PropertyInfo[], string, IDictionary<string, object>, int> excute = (propertys, condition, parameters) =>
 31             {
 32                 List<string> names = new List<string>();
 33                 foreach (PropertyInfo property in propertys)
 34                 {
 35                     if (property.GetCustomAttribute(typeof(IncrementAttribute)) == null)
 36                     {
 37                         string attrName = property.Name;
 38                         object value = property.GetValue(entity);
 39                         names.Add(string.Format("@{0}", attrName));
 40                         parameters.Add(attrName, value);
 41                     }
 42                 }
 43                 string sql = "Insert into {0} values({1})";
 44                 string combineSql = string.Format(sql, tableName, string.Join(",", names), builder.Value.Condition);
 45                 return unitOfWork.Command(combineSql, parameters);
 46             };
 47             return CreateExcute<int>(null, excute);
 48         }
 49 
 50         /// <summary>
 51         /// 修改对象
 52         /// </summary>
 53         /// <param name="entity"></param>
 54         /// <param name="express"></param>
 55         public virtual int Update(T entity, Expression<Func<T, bool>> express)
 56         {
 57 
 58             Func<PropertyInfo[], string, IDictionary<string, object>, int> excute = (propertys, condition, parameters) =>
 59             {
 60                 List<string> names = new List<string>();
 61                 foreach (PropertyInfo property in propertys)
 62                 {
 63                     if (property.GetCustomAttribute(typeof(IncrementAttribute)) == null)
 64                     {
 65                         string attrName = property.Name;
 66                         object value = property.GetValue(entity);
 67                         names.Add(string.Format("{0}=@{1}", attrName, attrName));
 68                         parameters.Add(attrName, value);
 69                     }
 70                 }
 71                 string sql = "update {0} set {1} where {2}";
 72                 string combineSql = string.Format(sql, tableName, string.Join(",", names), builder.Value.Condition);
 73                 return unitOfWork.Command(combineSql, parameters);
 74             };
 75             return CreateExcute<int>(express, excute);
 76         }
 77         /// <summary>
 78         /// 删除对象
 79         /// </summary>
 80         /// <param name="express"></param>
 81         public virtual int Delete(Expression<Func<T, bool>> express = null)
 82         {
 83             Func<PropertyInfo[], string, IDictionary<string, object>, int> excute = (propertys, condition, parameters) =>
 84             {
 85                 string sql = "delete from {0} {1}";
 86                 string combineSql = string.Format(sql, tableName, condition);
 87                 return unitOfWork.Command(combineSql, parameters);
 88             };
 89             return CreateExcute<int>(express, excute);
 90         }
 91 
 92         /// <summary>
 93         /// 查询对象集合
 94         /// </summary>
 95         /// <param name="express"></param>
 96         /// <returns></returns>
 97         public virtual List<T> QueryAll(Expression<Func<T, bool>> express = null)
 98         {
 99             Func<PropertyInfo[], string, IDictionary<string, object>, List<T>> excute = (propertys, condition, parameters) =>
100             {
101                 string sql = "select {0} from {1} {2}";
102                 string combineSql = string.Format(sql, string.Join(",", propertys.Select(x => x.Name)), tableName, condition);
103                 return context.ReadValues<T>(combineSql, parameters);
104             };
105             return CreateExcute<List<T>>(express, excute);
106         }
107 
108         /// <summary>
109         /// 查询对象集合(分页)
110         /// </summary>
111         /// <param name="index"></param>
112         /// <param name="pagesize"></param>
113         /// <param name="order"></param>
114         /// <param name="asc"></param>
115         /// <param name="express"></param>
116         /// <returns></returns>
117         public virtual List<T> QueryAll(int index,int pagesize,List<PropertySortCondition> orderFields,Expression<Func<T, bool>> express = null)
118         {
119             Func<PropertyInfo[], string, IDictionary<string, object>, List<T>> excute = (propertys, condition, parameters) =>
120             {
121                 if (orderFields == null) { throw new Exception("排序字段不能为空"); }
122                 string sql = "select * from (select {0} , ROW_NUMBER() over(order by {1}) as rownum from {2} {3}) as t where t.rownum >= {4} and t.rownum < {5}";
123                 string combineSql = string.Format(sql, string.Join(",", propertys.Select(x => x.Name)),string.Join(",", orderFields), tableName, condition, (index - 1) * pagesize + 1, index * pagesize);
124                 return context.ReadValues<T>(combineSql, parameters);
125             };
126             return CreateExcute<List<T>>(express, excute);
127         }
128 
129         /// <summary>
130         /// 查询对象集合
131         /// </summary>
132         /// <param name="type"></param>
133         /// <param name="express"></param>
134         /// <returns></returns>
135         public virtual List<object> QueryAll(Type type, Expression<Func<T, bool>> express = null)
136         {
137             Func<PropertyInfo[], string, IDictionary<string, object>, List<object>> excute = (propertys, condition, parameters) =>
138             {
139                 string sql = "select {0} from {1} {2}";
140                 string combineSql = string.Format(sql, string.Join(",", propertys.Select(x => x.Name)), tableName, condition);
141                 return context.ReadValues(combineSql, type, parameters);
142             };
143             return CreateExcute<List<object>>(express, excute);
144         }
145 
146         /// <summary>
147         /// 查询对象
148         /// </summary>
149         /// <param name="express"></param>
150         /// <returns></returns>
151         public virtual T Query(Expression<Func<T, bool>> express)
152         {
153             Func<PropertyInfo[], string, IDictionary<string, object>, T> excute = (propertys, condition, parameters) =>
154             {
155                 string sql = "select {0} from {1} {2}";
156                 string combineSql = string.Format(sql, string.Join(",", propertys.Select(x => x.Name)), tableName, condition);
157                 return context.ExecuteReader<T>(combineSql, parameters);
158             };
159             return CreateExcute<T>(express, excute);
160         }
161 
162         /// <summary>
163         /// 查询数量
164         /// </summary>
165         /// <param name="express"></param>
166         /// <returns></returns>
167         public virtual object QueryCount(Expression<Func<T, bool>> express = null)
168         {
169             Func<PropertyInfo[], string, IDictionary<string, object>, object> excute = (propertys, condition, parameters) =>
170             {
171                 string sql = "select * from {0} {1}";
172                 string combineSql = string.Format(sql, string.Join(",", propertys.Select(x => x.Name)), tableName, condition);
173                 return context.ExecuteScalar(combineSql, parameters);
174             };
175 
176             return CreateExcute<object>(express, excute);
177         }
178 
179         private TValue CreateExcute<TValue>(Expression<Func<T, bool>> express, Func<PropertyInfo[], string, IDictionary<string, object>, TValue> excute)
180         {
181             Dictionary<string, object> parameters = new Dictionary<string, object>();
182             PropertyInfo[] propertys = typeof(T).GetProperties();
183             string condition = "";
184             if (express != null)
185             {
186                 builder.Value.Build(express, tableName);
187                 condition = string.Format("where {0} ", builder.Value.Condition);
188                 for (int i = 0; i < builder.Value.Arguments.Length; i++)
189                 {
190                     parameters.Add(string.Format("Param{0}", i), builder.Value.Arguments[i]);
191                 }
192             }
193             return excute(propertys, condition, parameters);
194         }
195     }

接下来，定义工作单元，所有的添加、删除、修改操作都会被储存到工作单元中。

 1 public interface IUnitOfWork
 2     {
 3         /// <summary>
 4         /// 命令
 5         /// </summary>
 6         /// <param name="commandText"></param>
 7         /// <param name="parameters"></param>
 8         /// <returns></returns>
 9         int Command(string commandText, IDictionary<string, object> parameters);
10 
11         /// <summary>
12         /// 事务的提交状态
13         /// </summary>
14         bool IsCommited { get; set; }
15 
16         /// <summary>
17         /// 提交事务
18         /// </summary>
19         /// <returns></returns>
20         void Commit();
21 
22         /// <summary>
23         /// 回滚事务
24         /// </summary>
25         void RollBack();
26     }

接下来是对工作单元的实现，其内部维护了一个命令集合，存储Sql语句。

 1 public class UnitOfWork:IUnitOfWork
 2     {
 3         /// <summary>
 4         /// 注入对象
 5         /// </summary>
 6         private IUnitOfWorkContext context;
 7 
 8         /// <summary>
 9         /// 维护一个Sql语句的命令列表
10         /// </summary>
11         private List<CommandObject> commands;
12 
13         public UnitOfWork(IUnitOfWorkContext context)
14         {
15             commands = new List<CommandObject>();
16             this.context = context;
17         }
18 
19         /// <summary>
20         /// 增、删、改命令 
21         /// </summary>
22         /// <param name="commandText"></param>
23         /// <param name="parameters"></param>
24         /// <returns></returns>
25         public int Command(string commandText, IDictionary<string, object> parameters)
26         {
27             IsCommited = false;
28             commands.Add(new CommandObject(commandText, parameters));
29             return 1;
30         }
31 
32         /// <summary>
33         /// 提交状态
34         /// </summary>
35         public bool IsCommited{ get; set; }
36 
37         /// <summary>
38         /// 提交方法
39         /// </summary>
40         /// <returns></returns>
41         public void Commit()
42         {
43             if (IsCommited) { return ; }
44             using (TransactionScope scope = new TransactionScope())
45             {
46                 foreach (var command in commands)
47                 {
48                     context.ExecuteNonQuery(command.command, command.parameters);
49                 }
50                 scope.Complete();
51                 IsCommited = true;
52             }
53         }
54 
55         /// <summary>
56         /// 事务回滚
57         /// </summary>
58         public void RollBack()
59         {
60             IsCommited = false;
61         }
62     }

最后定义工作单元对事务提交处理的上下文及其实现，同仓储模式中的代码。

 1 public interface IUnitOfWorkContext
 2     {
 3 
 4         /// <summary>
 5         /// 注册新对象到上下文
 6         /// </summary>
 7         /// <param name="commandText"></param>
 8         /// <param name="parameters"></param>
 9         int ExecuteNonQuery(string commandText, IDictionary<string, object> parameters = null);
10 
11         /// <summary>
12         ///  查询对象集合
13         /// </summary>
14         /// <typeparam name="T"></typeparam>
15         /// <param name="commandText"></param>
16         /// <param name="parameters"></param>
17         /// <param name="load">自定义处理</param>
18         /// <returns></returns>
19         List<T> ReadValues<T>(string commandText, IDictionary<string, object> parameters = null, Func<IDataReader, T> load = null) where T : class, new();
20 
21         /// <summary>
22         /// 查询对象集合
23         /// </summary>
24         /// <param name="commandText"></param>
25         /// <param name="type"></param>
26         /// <param name="parameters"></param>
27         /// <param name="setItem"></param>
28         /// <returns></returns>
29         List<object> ReadValues(string commandText, Type type, IDictionary<string, object> parameters = null, Action<dynamic> setItem = null);
30 
31         /// <summary>
32         /// 查询对象
33         /// </summary>
34         /// <typeparam name="TEntity"></typeparam>
35         /// <param name="commandText"></param>
36         /// <param name="parameters"></param>
37         /// <param name="excute"></param>
38         /// <returns></returns>
39         T ExecuteReader<T>(string commandText, IDictionary<string, object> parameters = null, Func<IDataReader, T> load = null) where T : class,new();
40 
41         /// <summary>
42         /// 查询数量
43         /// </summary>
44         /// <param name="commandText"></param>
45         /// <param name="parameters"></param>
46         /// <returns></returns>
47         object ExecuteScalar(string commandText, IDictionary<string, object> parameters = null);
48     }

最后实现。

  1 public abstract class UnitOfWorkContext : IUnitOfWorkContext,IDisposable
  2     {
  3         /// <summary>
  4         /// 数据库连接字符串标识
  5         /// </summary>
  6         public abstract string Key { get; }
  7 
  8         private SqlConnection connection;
  9 
 10         private SqlConnection Connection 
 11         {
 12             get 
 13             {
 14                 if (connection == null)
 15                 {
 16                     ConnectionStringSettings settings = ConfigurationManager.ConnectionStrings[Key];
 17                     connection = new SqlConnection(settings.ConnectionString);
 18                 }
 19                 return connection;
 20             }    
 21         }
 22 
 23         /// <summary>
 24         /// 注册新对象到事务
 25         /// </summary>
 26         /// <typeparam name="TEntity"></typeparam>
 27         /// <param name="entity"></param>
 28         public int ExecuteNonQuery(string commandText, IDictionary<string, object> parameters = null)
 29         {
 30             Func<SqlCommand, int> excute = (commend) =>
 31             {
 32                 return commend.ExecuteNonQuery();
 33             };
 34             return CreateDbCommondAndExcute<int>(commandText, parameters, excute);
 35         }
 36 
 37         /// <summary>
 38         /// 查询对象集合
 39         /// </summary>
 40         /// <typeparam name="T"></typeparam>
 41         /// <param name="commandText"></param>
 42         /// <param name="parameters"></param>
 43         /// <param name="load">自定义处理</param>
 44         /// <returns>泛型实体集合</returns>
 45 
 46         public List<T> ReadValues<T>(string commandText, IDictionary<string, object> parameters = null, Func<IDataReader, T> load = null) where T : class,new()
 47         {
 48             Func<SqlCommand, List<T>> excute = (dbCommand) =>
 49             {
 50                 List<T> result = new List<T>();
 51                 using (IDataReader reader = dbCommand.ExecuteReader())
 52                 {
 53                     while (reader.Read())
 54                     {
 55                         if (load == null)
 56                         {
 57                             load = (s) => { return s.GetReaderData<T>(); };
 58                         }
 59                         var item = load(reader);
 60                         result.Add(item);
 61                     }
 62                     return result;
 63                 }
 64             };
 65             return CreateDbCommondAndExcute(commandText, parameters, excute);
 66         }
 67 
 68         /// <summary>
 69         /// 查询对象集合
 70         /// </summary>
 71         /// <param name="commandText"></param>
 72         /// <param name="parameters"></param>
 73         /// <param name="setItem"></param>
 74         /// <returns></returns>
 75         public List<object> ReadValues(string commandText, Type type, IDictionary<string, object> parameters = null, Action<dynamic> setItem = null)
 76         {
 77             Func<SqlCommand, List<object>> excute = (dbCommand) =>
 78             {
 79                 var result = new List<object>();
 80 
 81                 using (IDataReader dataReader = dbCommand.ExecuteReader())
 82                 {
 83                     while (dataReader.Read())
 84                     {
 85                         var item = dataReader.GetReaderData(type);
 86                         if (setItem != null)
 87                         {
 88                             setItem(item);
 89                         }
 90                         result.Add(item);
 91                     }
 92                 }
 93                 return result;
 94             };
 95             return CreateDbCommondAndExcute<List<object>>(commandText, parameters,
 96                 excute);
 97         }
 98 
 99         /// <summary>
100         /// 查询对象
101         /// </summary>
102         /// <typeparam name="TEntity"></typeparam>
103         /// <param name="commandText"></param>
104         /// <param name="parameters"></param>
105         /// <param name="excute"></param>
106         /// <returns></returns>
107         public T ExecuteReader<T>(string commandText, IDictionary<string, object> parameters = null, Func<IDataReader, T> load = null) where T : class,new()
108         {
109             Func<SqlCommand, T> excute = (dbCommand) =>
110             {
111                 var result = default(T);
112                 using (IDataReader reader = dbCommand.ExecuteReader())
113                 {
114                     while (reader.Read())
115                     {
116                         if (load == null)
117                         {
118                             load = (s) => { return s.GetReaderData<T>(); };
119                         }
120                         result = load(reader);
121                     }
122                     return result;
123                 }
124             };
125             return CreateDbCommondAndExcute<T>(commandText, parameters, excute);
126         }
127 
128         /// <summary>
129         /// 查询数量
130         /// </summary>
131         /// <param name="commandText"></param>
132         /// <param name="parameters"></param>
133         /// <returns></returns>
134         public object ExecuteScalar(string commandText, IDictionary<string, object> parameters = null)
135         {
136             Func<SqlCommand, object> excute = (dbCommand) =>
137             {
138                 return dbCommand.ExecuteScalar();
139             };
140             return CreateDbCommondAndExcute(commandText, parameters, excute);
141         }
142 
143         /// <summary>
144         /// 创建命令并执行
145         /// </summary>
146         /// <typeparam name="TValue"></typeparam>
147         /// <param name="commandText"></param>
148         /// <param name="parameters"></param>
149         /// <param name="excute"></param>
150         /// <returns></returns>
151         private TValue CreateDbCommondAndExcute<TValue>(string commandText,
152             IDictionary<string, object> parameters, Func<SqlCommand, TValue> excute)
153         {
154             if (Connection.State == ConnectionState.Closed) { Connection.Open(); };
155             using (SqlCommand command = new SqlCommand())
156             {
157                 command.CommandType = CommandType.Text;
158                 command.CommandText = commandText;;
159                 command.Connection = Connection;
160                 command.SetParameters(parameters);
161                 return excute(command);
162             }
163         }
164 
165         /// <summary>
166         /// 关闭连接
167         /// </summary>
168         public void Dispose()
169         {
170             if (connection != null)
171             {
172                 Connection.Dispose();//非托管资源
173             }
174         }
175     }

View Code

在调用方法时需要注意，一个事务涉及多个聚合时，需要保证传递同一工作单元，并在方法的最后调用Commit() 方法。

 1 public class Services : IService
 2     {
 3         private IMemberRespository member;
 4 
 5         private IUnitOfWork unitOfWork;
 6 
 7         public Services(IMemberRespository member, IUnitOfWork unitOfWork)
 8         {
 9             this.member = member;
10             this.unitOfWork = unitOfWork;
11         }
12 
13         /// <summary>
14         /// 测试用例
15         /// </summary>
16         public void Demo()
17         {
18 
19             member.Test();
20 
21             unitOfWork.Commit();
22         }
23     }

后记

至此，既实现对数据访问层和领域层解耦，如果园友对我的比较认可，欢迎尝试去使用，在使用中遇到什么问题或有什么好的意见，也希望及时反馈给我。若某些园友不太认可我的设计，也希望批评指出。

【.Net设计模式系列】工作单元(Unit Of Work)模式 ( 二 )

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原文地址：http://www.cnblogs.com/retop/p/5193394.html

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