c# KeyValuePair用法

C# KeyValuePair<TKey,TValue>的用法。結構體，定義可設置或檢索的鍵/值對。也就是說我們可以通過 它記錄一個鍵/值對這樣的值。比如我們想定義一個ID(int類型)和Name(string類型)這樣的鍵/值對，那么可以這 樣使用

private KeyValuePair<int, string> SetKeyValuePair()
{
    int intKey = 1;
    string strValue = "My value";
    KeyValuePair<int, string> kvp = new KeyValuePair<int, string>(intKey, strValue);
    return kvp;
}

/// <summary>
/// 獲得鍵/值對
/// </summary>
private void GetKeyValuePairDemo()
{
    KeyValuePair<int, string> kvp = SetKeyValuePair();
    int intKey = kvp.Key;
    string strValue = kvp.Value;
}

 

 

如果想使用泛型的話，一般批量讀取數據的時候，當只需要讀兩個字段(Id and Name)時， 如果想不用Model類，並配合泛型使用KeyValuePair，示例：

///綁定一個cmbobox數據項
public void cmbDate{

List<KeyValuePair<object, string>> dit = new List<KeyValuePair<object, string>>();

if (Helper.GlobalVariables.Gi_Language_Type == 1)
{
dit.Add(new KeyValuePair<object, string>(1, "身份證"));
dit.Add(new KeyValuePair<object, string>(2, "軍官證"));
dit.Add(new KeyValuePair<object, string>(3, "護照"));
dit.Add(new KeyValuePair<object, string>(4, "其他"));
}
else
{
dit.Add(new KeyValuePair<object, string>(1, "Identity card"));
dit.Add(new KeyValuePair<object, string>(2, "Officer certificate"));
dit.Add(new KeyValuePair<object, string>(3, "Passport"));
dit.Add(new KeyValuePair<object, string>(4, "Other"));
}
this.cmbCertificate_type.DataSource = dit;
this.cmbCertificate_type.DisplayMember = "Value";
this.cmbCertificate_type.ValueMember = "Key";

}

　　

/// <summary>
/// 獲取所有企業的Id(enterprise_id)及英文名 (enterprise_name_eng)
/// </summary>
/// <returns>enterprise_info表中的所有企業 Id及英文名</returns>
public List<KeyValuePair<long,string>> GetEnterpriseIdAndNameEngList()
{
    //enterprise_id鍵和enterprise_name_eng 對
    List<KeyValuePair<long, string>> lstIdKeyNameEngValue = new List<KeyValuePair<long, string>>();

 

    string cmdText = "select enterprise_id, enterprise_name_eng from enterprise_info";
    using (OracleDataReader reader = OracleHelper.ExecuteReader(OracleHelper.OracleConnString, CommandType.Text, cmdText, null)) 
    {
        try
        {
            MyEventLog.Log.Debug ("cmdText= " + cmdText);
            while (reader.Read())
            {
                KeyValuePair<long, string> idKeyNameEngValue = new KeyValuePair<long, string> (
               &nbs p;    reader.IsDBNull(0) ? 0 : reader.GetInt64(0), 
                 ;    reader.IsDBNull(1) ? string.Empty : reader.GetString(1) 
                 ;    );
                lstIdKeyNameEngValue.Add (idKeyNameEngValue);
            } 
            OracleHelper.DataReaderClose(reader);
        } 
        catch (OracleException e) 
        {
            MyEventLog.Log.Error ("cmdText= " + cmdText);
            MyEventLog.Log.Error(e);
            throw e;
        }
    } 
    return lstIdKeyNameEngValue;
}

 

2、在業務中處理數據

 

/// <param name="lstEnterpriseNameEn">待導入的企業名稱(英文)集</param>
/// <param name="lstValidRowsIndex">Excel表中有效的企業Id行集</param>
/// <param name="lstInvalidRowsIndex">Excel表中無效的企業Id行集</param>
/// <returns>返回有效的行的索引列表</returns>
public List<long> PrepareForImport(List<string> lstEnterpriseNameEn, out List<int> lstValidRowsIndex, out List<int> lstInvalidRowsIndex)
{
    //有效的企業Id行
    lstValidRowsIndex = new List<int>();
    //無效的企業Id行
    lstInvalidRowsIndex = new List<int>();     //獲取所有的企業Id及英文名
    List<KeyValuePair<long, string>> lstIdKeyNameEngValue = dal.GetEnterpriseIdAndNameEngList();     //用於存放有效的企業的Id，即如果可以在enterprise_info表中找到此企業的英文名，那么表示此企業存在，因此把存在的企業Id獲取出來，存放於此變量
    List<long> lstValidEnterpriseId = new List<long>();     //通過以下循環可以獲得可以有效的企業Id列表
    for (int i = 0; i < lstEnterpriseNameEn.Count; i++)
    {
        foreach (KeyValuePair<long, string> kvp in lstIdKeyNameEngValue)
        {
            if (lstEnterpriseNameEn[i] == kvp.Value)
            {
                //獲得有效行索引
                lstValidRowsIndex.Add(i);                 //獲得有效的企業Id
                lstValidEnterpriseId.Add(kvp.Key);                 //找到了有效的ID后馬上跳出內循環，回到外循環
                continue;
            }
        }         if (!lstValidRowsIndex.Contains(i) && !lstInvalidRowsIndex.Contains(i))
        {
            //取得無效行索引
            lstInvalidRowsIndex.Add(i);
        }
    }
    return lstValidEnterpriseId;
}