C＃抽象方法

Question

我有一組方法，它們包含日期和布爾值。然後這些方法使用一些SQL，然後將它傳遞給另一個方法並返回一個列表。每種方法都與返回的SQL和List的例外幾乎相同。現在我知道有更好的方法做這些方法，但我不知道如何。

有沒有人有任何想法，我可以如何抽象或使用更好的設計，因爲方法幾乎相同？

下面是代碼：

private List<ENT_Message> GetMessageData(DateTime? startDate, DateTime? endDate, bool IsSelectAll) 
{ 
    List<ENT_Message> ret = new List<ENT_Message>(); 
    string sql = ""; 

    if (IsSelectAll) 
    { 
     sql = "select * from tbl_message"; 
    } 
    else 
    { 
     sql = " Select * from tbl_message where created_Date between @start_Date and @end_date"; 
    } 

    return Converter.SerializeToMessageList(this.GetData(startDate, endDate, IsSelectAll, sql));     
} 

private List<ENT_SensorData> GetSensorData(DateTime? startDate, DateTime? endDate, bool IsSelectAll) 
{ 
    List<ENT_SensorData> ret = new List<ENT_SensorData>(); 
    string sql = ""; 

    if (IsSelectAll) 
    { 
     sql = "select * from tbl_sensor_data"; 
    } 
    else 
    { 
     sql = "select * from tbl_sensor_data where Timestamp between @start_date and @end_Date"; 
    } 

    return Converter.SerializeToSensorDataList(this.GetData(startDate, endDate, IsSelectAll, sql)); 
} 

private List<ENT_SensorDataEvent> GetSensorDataEvents(DateTime? startDate, DateTime? endDate, bool IsSelectAll) 
{ 
    List<ENT_SensorDataEvent> ret = new List<ENT_SensorDataEvent>(); 
    string sql = ""; 

    if (IsSelectAll) 
    { 
     sql = "select * from tbl_sensor_data_event"; 
    } 
    else 
    { 
     sql = "select * from tbl_sensor_data_event where start_time between @start_date and @end_Date"; 
    } 

    return Converter.SerializeToSensorEventDataList(this.GetData(startDate, endDate, IsSelectAll, sql)); 
} 

private List<ENT_SensorDataState> GetSensorDataState(DateTime? startDate, DateTime? endDate, bool IsSelectAll) 
{ 
    List<ENT_SensorDataState> ret = new List<ENT_SensorDataState>(); 
    string sql = ""; 

    if (IsSelectAll) 
    { 
     sql = "select * from tbl_sensor_data_state"; 
    } 
    else 
    { 
     sql = "select * from tbl_sensor_data_state where start_time between @start_date and @end_Date"; 
    } 

    return Converter.SerializeToSensorDateStateList(this.GetData(startDate, endDate, IsSelectAll, sql)); 
} 

private List<ENT_WorkOrder> GetWorkOrders(DateTime? startDate, DateTime? endDate, bool IsSelectAll) 
{ 
    List<ENT_WorkOrder> ret = new List<ENT_WorkOrder>(); 
    string sql = ""; 

    if (IsSelectAll) 
    { 
     sql = "select * from tbl_workorder"; 
    } 
    else 
    { 
     sql = "select * from tbl_sensor_data_state where completed_date between @start_date and @end_Date"; 
    } 

    return Converter.SerializeToWorkOrderList(this.GetData(startDate, endDate, IsSelectAll, sql)); 
} 

Answer 1

你可以大大縮短你的功能。例如，而不是

private List<ENT_SensorDataState> GetSensorDataState(DateTime? startDate, DateTime? endDate, bool IsSelectAll) 
{ 
    List<ENT_SensorDataState> ret = new List<ENT_SensorDataState>(); 
    string sql = ""; 

    if (IsSelectAll) 
    { 
     sql = "select * from tbl_sensor_data_state"; 
    } 
    else 
    { 
     sql = "select * from tbl_sensor_data_state where start_time between @start_date and @end_Date"; 
    } 

    return Converter.SerializeToSensorDateStateList(this.GetData(startDate, endDate, IsSelectAll, sql)); 
} 

你可以簡單地寫

private List<ENT_SensorDataState> GetSensorDataState(DateTime? startDate, DateTime? endDate, bool IsSelectAll) 
{ 
    string sql = "select * from tbl_sensor_data_state" 
       + (IsSelectAll ? "" : "where start_time between @start_date and @end_Date"); 

    return Converter.SerializeToSensorDateStateList(this.GetData(startDate, endDate, IsSelectAll, sql)); 
} 

，基本上降低了你的函數真正重要的東西：在SQL和序列化功能的名稱。

Answer 2

private List<T> GetData<T>(DateTime? startDate, DateTime? endDate, bool IsSelectAll) 
     { 
      List<T> ret = new List<T>(); 

      string tableName = "";//Select the table name based on T here 
      string sql = ""; 

      if (IsSelectAll) 
      { 
       sql = "select * from tbl_sensor_data"; 
      } 
      else 
      { 
       sql = "select * from tbl_sensor_data where Timestamp between @start_date and @end_Date"; 
      } 
      //Build your list using the appropriate converter based on T here   
      return Converter.SerializeToSensorDataList(this.GetData(startDate, endDate, IsSelectAll, sql)); 
     } 

從這一點上來說，你只

GetData<ENT_whatever>() 

調用。

Answer 3

如果你存儲你的sql語句和一個委託方法在一個映射中的鍵是某種類型T，然後讓你的方法是通用的（方法需要類型T並返回T的List），你可以做一個地圖查找來獲得正確的sql語句和委託方法。

Answer 4

看起來你有機會做一個通用的方法。如果我有語法錯誤，我很抱歉。

private List<T> GetData<T>(DateTime? startDate, DateTime? endDate, bool IsSelectAll) where T : ENT_Data 
{ 
    List<T> ret = new List<T>(); 
    string sql = ""; 

    if (IsSelectAll) 
    { 
     sql = "select * from " + T.table; 
    } 
    else 
    { 
     sql = " Select * from " + T.table + " where created_Date between @start_Date and @end_date"; 
    } 

    return Converter.Serialize<T>(this.GetData(startDate, endDate, IsSelectAll, sql));  
} 

注意的幾件事情我做：

1. 的一般方法具有約束T是ENT_Data，我只是做了一個類型的子類。
2. 我給了ENT_Data類型一個table字段，用於您的查詢。
3. Converter.Serialize方法也以類似的方式被製作爲通用的。

如果我錯過了任何重要的事情，請讓我知道。

Answer 5

您可以創建一個SqlRetriever類，然後將每個子類與要發送的特定SQL消息進行子類化。

class SqlRetriever { 
    public abstract void SendSqlCmd(); 
    public ArrayList List { 
     get; set; 
    } 
} 

class SqlRetrieverXXX 
    public const string SqlCmd = " ... "; 
    public override void SendSqlCmd() 
    { 
     /* ... */ 
    } 
} 

另一種可能性，涉及少classses，與不良的設計是以下之一：

class SqlRetriever { 
     public const string SQLCmd1 = "..."; 
     public const string SQLCmd2 = "..."; 

     public void SendSqlCmd(string sqlcmd) 
     { 
      /*Send the SQL Cmd and store the result in the list */ 
     } 

     public ArrayList List { 
      get; set; 
     } 

     public static ArrayList DoSqlCmd(string sqlCmd) 
     { 
      var obj = new SqlRetriever(); 

      obj.SendSqlCmd(sqlCmd); 

      return obj.List; 
     } 
} 

Answer 6

你可以有一個基類的所有ENT_ *類繼承。然後製作一個方法列表<ENT_Base> GetData（yourParams）。創建一個工廠方法，根據ENT_Base的類型獲取實體列表。 你的GetData（）調用並返回它。 你不會繞過開關盒或者如果然後找出你必須返回哪種實體。