DataReader转换为实体的应用

一时失言乱红尘 2021-12-24 15:17 243阅读 0赞

![ContractedBlock.gif][] ![ExpandedBlockStart.gif][] 代码

－－－－DataReader转换为实体的泛型类－－－  
        注意 数据库表字段名和实体类相同  
         public   class  EntityTranslate  
        \{  
             ///  用class关键字表示约束为引用类型  
             ///  用struct关键字表示约束为值类型  
             ///  new()默认构造函数约束：如果需要在泛型类型内部实例化类型参数的对象，  
            /// 就必须对类型参数加以默认构造函数约束，除此之外别无选择。   
            // 执行查询返回对象集合    
            public   static  List < TEntity >  Translate < TEntity > (IDataReader reader)  where  TEntity :  class ,  new ()   
            \{  
                List < TEntity >  list  =   new  List < TEntity > ();  
                Type entityType  =   typeof (TEntity);  
                 // 创建实例   
                  object  entity  =  Activator.CreateInstance(entityType);  
                List < string >  attributes  =   new  List < string > ();  
                Dictionary < string , PropertyInfo >  dic  =   new  Dictionary < string , PropertyInfo > ();  
                 foreach  (PropertyInfo info  in  entityType.GetProperties())  
                \{  
                    dic.Add(info.Name, info);  
                \}  
  
                 string  columnName  =   string .Empty;  
                 // object\[\] attributes = info.GetCustomAttributes(true);   
                  while  (reader.Read())  
                \{  
                    TEntity t  =   new  TEntity();  
                     foreach  (KeyValuePair < string , PropertyInfo >  attribute  in  dic)  
                    \{  
                        columnName  =  attribute.Key;  
                         int  filedIndex  =   0 ;  
                         while  (filedIndex  <  reader.FieldCount)  
                        \{  
  
                             if  (reader.GetName(filedIndex)  ==  columnName)  
                            \{  
                                attribute.Value.SetValue(t, reader\[filedIndex\],  null );  
                                 break ;  
  
                            \}  
                            filedIndex \++ ;  
  
  
                        \}  
                    \}  
                    list.Add(t);  
  
                \}  
                 return  list;  
  
            \}  
        \}  
      实现代码：  
        public   void  ReaderToEntity()  
        \{  
             string  sql  =   " select \* from T\_User " ;  
            IDataReader reader  =  DAO.GetReader(sql);  
            List < User >  list  =  EntityTranslate.Translate < User > (reader);  
             foreach  (User user  in  list)  
            \{  
                Console.WriteLine( " 用户ID: "   \+  user.Id.ToString()  \+   "  用户名： "    
                 \+  user.UserName  \+   "  密码: "   \+  user.UserPwd);  
            \}  
            reader.Close();  
        \}

转载于:https://www.cnblogs.com/hubcarl/archive/2010/04/07/1706354.html

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