【.Net設計模式系列】倉儲(Repository)模式 ( 一 )

時間 2019-11-11

標籤 .Net設計模式系列倉儲 repository 模式简体版

原文原文鏈接

開篇

2016新年伊始，望眼過去，不知不覺在博客園已經註冊8個月啦，因爲最近忙於工做，博客遲遲沒有更新。直到最近一直研究.Net設計模式，對一些模式有所感悟，故拿出本身的心得與你們分享，在接下來的全部博客中我都會以【理論介紹】和【具體實踐】兩個方面來敘述對模式的應用。數據庫

理論介紹

倉儲(Respository)是存在於工做單元和數據庫之間單獨分離出來的一層，是對數據訪問的封裝。其優勢：設計模式

　　　　1）業務層不須要知道它的具體實現，達到了分離關注點。this

　　　　2）提升了對數據庫訪問的維護，對於倉儲的改變並不會改變業務的邏輯，數據庫能夠用Sql Server（該系列博客使用）、MySql等。spa

具體實踐

首先，建立IRepository.cs接口定義對數據操做的契約(命令執行、重載不一樣查詢結果集合、查詢實體、查詢返回結果值)。設計

 1     /// <summary>
 2     /// Ado.Net實現的倉儲
 3     /// </summary>
 4     public interface IRepository
 5     {
 6         /// <summary>
 7         /// 增、刪、改對象
 8         /// </summary>
 9         /// <param name="commandText">Sql語句</param>
10         /// <param name="parameters">參數</param>
11         /// <param name="isCommit">是否提交</param>
12         /// <returns></returns>
13         void Command(string commandText, IDictionary<string, object> parameters = null);
14 
15         /// <summary>
16         /// 查詢對象集合
17         /// </summary>
18         /// <typeparam name="T">返回值的實體類型</typeparam>
19         /// <param name="commandText">Sql語句</param>
20         /// <param name="parameters">參數</param>
21         /// <param name="isCommit">是否提交</param>
22         /// <returns>泛型實體集合</returns>
23         List<T> QueryAll<T>(string commandText, IDictionary<string, object> parameters = null) where T : class, new();
24 
25         /// <summary>
26         /// 查詢對象集合
27         /// </summary>
28         /// <param name="commandText"></param>
29         /// <param name="type"></param>
30         /// <param name="parameters"></param>
31         /// <param name="isCommit"></param>
32         /// <returns></returns>
33         List<object> QueryAll(string commandText, Type type, IDictionary<string, object> parameters = null);
34 
35         /// <summary>
36         /// 查詢對象
37         /// </summary>
38         /// <typeparam name="TEntity"></typeparam>
39         /// <param name="commandText"></param>
40         /// <param name="type"></param>
41         /// <param name="parameters"></param>
42         /// <returns></returns>
43         T Query<T>(string commandText, IDictionary<string, object> parameters = null) where T : class,new();
44 
45         /// <summary>
46         /// 查詢數量
47         /// </summary>
48         /// <param name="commandText"></param>
49         /// <param name="parameters"></param>
50         /// <returns></returns>
51         object QueryCount(string commandText, IDictionary<string, object> parameters = null);
52     }

其次，定義抽象類BaseRepository.cs實現倉儲。code

  1     /// <summary>
  2     /// 基礎庫實現
  3     /// </summary>
  4     public abstract class BaseRepository : IRepository
  5     {
  6     /// <summary>
  7         /// 數據庫鏈接字符串標識
  8         /// </summary>
  9         public abstract string Key { get; }
 10 
 11         private SqlConnection connection;
 12 
 13         private SqlConnection Connection 
 14         {
 15             get 
 16             {
 17                 if (connection == null)
 18                 {
 19                     ConnectionStringSettings settings = ConfigurationManager.ConnectionStrings[Key];
 20                     connection = new SqlConnection(settings.ConnectionString);
 21                 }
 22                 return connection;
 23             }    
 24         }
 25 
 26         /// <summary>
 27         /// 增、刪、改命令
 28         /// </summary>
 29         /// <param name="commandText"></param>
 30         /// <param name="parameters"></param>
 31         public virtual void Command(string commandText, IDictionary<string, object> parameters = null)
 32         {
 33             Func<SqlCommand, int> excute = (commend) =>
 34             {
 35                 return commend.ExecuteNonQuery();
 36             };
 37             CreateDbCommondAndExcute<int>(commandText, parameters, excute);
 38         }
 39 
 40         /// <summary>
 41         /// 查詢實體（強類型）
 42         /// </summary>
 43         /// <typeparam name="T"></typeparam>
 44         /// <param name="commandText"></param>
 45         /// <param name="parameters"></param>
 46         /// <returns></returns>
 47         public virtual T Query<T>(string commandText, IDictionary<string, object> parameters = null,Func<IDataReader, T> load = null) where T : class, new()
 48         {
 49             Func<SqlCommand, T> excute = (dbCommand) =>
 50             {
 51 
 52                 var result = default(T);
 53                 using (IDataReader reader = dbCommand.ExecuteReader())
 54                 {
 55                     while (reader.Read())
 56                     {
 57                         if (load == null)
 58                         {
 59                             load = (s) => { return s.GetReaderData<T>(); };
 60                         }
 61                         result = load(reader);
 62                     }
 63                     return result;
 64                 }
 65             };
 66             return CreateDbCommondAndExcute<T>(commandText, parameters, excute);
 67         }
 68 
 69         /// <summary>
 70         /// 查詢匿名對象集合
 71         /// </summary>
 72         /// <param name="commandText"></param>
 73         /// <param name="type"></param>
 74         /// <param name="parameters"></param>
 75         /// <returns></returns>
 76         public virtual List<object> QueryAll(string commandText, Type type, IDictionary<string, object> parameters = null,Action<dynamic> setItem = null)
 77         {
 78             Func<SqlCommand, List<object>> excute = (dbCommand) =>
 79             {
 80                 var result = new List<object>();
 81 
 82                 using (IDataReader dataReader = dbCommand.ExecuteReader())
 83                 {
 84                     while (dataReader.Read())
 85                     {
 86                         var item = dataReader.GetReaderData(type);
 87                         if (setItem != null)
 88                         {
 89                             setItem(item);
 90                         }
 91                         result.Add(item);
 92                     }
 93                 }
 94                 return result;
 95             };
 96             return CreateDbCommondAndExcute<List<object>>(commandText, parameters,
 97                 excute);
 98         }
 99 
100         /// <summary>
101         /// 查詢強類型對象集合
102         /// </summary>
103         /// <typeparam name="T"></typeparam>
104         /// <param name="commandText"></param>
105         /// <param name="parameters"></param>
106         /// <returns></returns>
107         public virtual List<T> QueryAll<T>(string commandText, IDictionary<string, object> parameters = null,Func<IDataReader, T> load = null) where T : class, new()
108         {
109            Func<SqlCommand, List<T>> excute = (dbCommand) =>
110             {
111                 List<T> result = new List<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                         var item = load(reader);
121                         result.Add(item);
122                     }
123                     return result;
124                 }
125             };
126             return CreateDbCommondAndExcute(commandText, parameters, excute);
127         }
128 
129         /// <summary>
130         /// 查詢結果數量
131         /// </summary>
132         /// <param name="commandText"></param>
133         /// <param name="parameters"></param>
134         /// <returns></returns>
135         public virtual object QueryCount(string commandText, IDictionary<string, object> parameters = null)
136         {
137              Func<SqlCommand, object> excute = (dbCommand) =>
138             {
139                 return dbCommand.ExecuteScalar();
140             };
141             return CreateDbCommondAndExcute(commandText, parameters, excute);
142         }
143 
144     /// <summary>
145         /// 建立命令並執行
146         /// </summary>
147         /// <typeparam name="TValue"></typeparam>
148         /// <param name="commandText"></param>
149         /// <param name="parameters"></param>
150         /// <param name="excute"></param>
151         /// <returns></returns>
152         private TValue CreateDbCommondAndExcute<TValue>(string commandText,
153             IDictionary<string, object> parameters, Func<SqlCommand, TValue> excute)
154         {
155             if (Connection.State == ConnectionState.Closed) { Connection.Open(); };
156             using (SqlCommand command = new SqlCommand())
157             {
158                 command.CommandType = CommandType.Text;
159                 command.CommandText = commandText;;
160                 command.Connection = Connection;
161                 command.SetParameters(parameters);
162                 return excute(command);
163             }
164         }
165 
166         /// <summary>
167         /// 關閉鏈接
168         /// </summary>
169         public void Dispose()
170         {
171             if (connection != null)
172             {
173                 Connection.Dispose();//非託管資源
174             }
175         }
176     }

最後，實現方法中的擴展方法。對象

  1     /// <summary>
  2     /// Sql Server 擴展類
  3     /// </summary>
  4     public static class SqlServerExtension
  5     {
  6         /// <summary>
  7         /// 設置參數
  8         /// </summary>
  9         /// <param name="dbCommand"></param>
 10         /// <param name="parameters"></param>
 11         public static void SetParameters(this IDbCommand dbCommand, IDictionary<string, object> parameters)
 12         {
 13             if (parameters == null)
 14             {
 15                 return;
 16             }
 17             foreach (var parameter in parameters)
 18             {
 19                 if (parameter.Value != null)
 20                 {
 21                     dbCommand.Parameters.Add(new SqlParameter(parameter.Key, parameter.Value));
 22                 }
 23                 else 
 24                 {
 25                     dbCommand.Parameters.Add(new SqlParameter(parameter.Key,DBNull.Value));    
 26                 }
 27             }
 28         }
 29 
 30         /// <summary>
 31         ///  獲取對應的實體
 32         /// </summary>
 33         /// <typeparam name="TEntity"></typeparam>
 34         /// <param name="TEntity"></param>
 35         /// <returns></returns>
 36         public static TEntity GetReaderData<TEntity>(this IDataReader reader) where TEntity : class, new()
 37         {
 38             var item = new TEntity();
 39             var filedList = new List<string>();
 40             for (int i = 0; i < reader.FieldCount; i++)
 41             {
 42                 filedList.Add(reader.GetName(i));
 43             }
 44             //映射數據庫中的字段到實體屬性
 45             IEnumerable<PropertyInfo> propertys = typeof(TEntity).GetProperties().Where(s => filedList.Contains(s.Name));
 46             foreach (var property in propertys)
 47             {
 48                 //對實體屬性進行設值
 49                 property.SetValue(item, reader[property.Name]);
 50             }
 51             return item;
 52         }
 53 
 54         /// <summary>
 55         /// 根據列名獲取值
 56         /// </summary>
 57         /// <typeparam name="T"></typeparam>
 58         /// <param name="reader"></param>
 59         /// <param name="columnName"></param>
 60         /// <returns></returns>
 61         public static T GetValue<T>(this IDataReader reader, string columnName)
 62         {
 63             int index = reader.GetOrdinal(columnName);
 64             if (reader.IsDBNull(index))
 65             { 
 66                 return default(T);
 67             }
 68             return (T)reader[index];
 69         }
 70 
 71         /// <summary>
 72         /// 獲取對應的實體
 73         /// </summary>
 74         /// <param name="reader"></param>
 75         /// <param name="type"></param>
 76         /// <returns></returns>
 77         public static object GetReaderData(this IDataReader reader,Type type)
 78         {
 79             var item = Activator.CreateInstance(type);
 80             var filedList = new List<string>();
 81             for (int i = 0; i < reader.FieldCount; i++)
 82             {
 83                 filedList.Add(reader.GetName(i).ToLower());
 84             }
 85             var properties = (from s in type.GetProperties()
 86                               let name = s.Name.ToLower().Split(new string[] { "_" }, StringSplitOptions.RemoveEmptyEntries).LastOrDefault()
 87                               where filedList.Contains(s.Name)
 88                               select new
 89                               {
 90                                   Name = s.Name,
 91                                   Property = s
 92                               }).ToList();
 93 
 94             foreach (var property in properties)
 95             {
 96                 property.Property.SetValue(item, reader[property.Name]);
 97             }
 98             return item;
 99         }
100     }