简单项目的简单数据库访问层封装（三）

时间：2011-03-02 来源：菜鸟老了

1、使用工厂模式建立访问类：

SqlQueryHelperBuilder

 1  public class SqlQueryHelperBuilder<T> where T : DBHelperModel, new()
 2     {
 3         private string TabelName;
 4       
 5         private string DataBaseEnginer = ConfigurationManager.AppSettings["SqlEngine"];
 6         public SqlQueryHelperBuilder()
 7         { 
 8         }
 9         public SqlQueryHelperBuilder(string TabelName)
10         {
11             if(string.IsNullOrEmpty(TabelName))
12                 throw new Exception("DataBase source tabel name request");
13             this.TabelName = TabelName;
14         }
15 
16         public ISqlSimpleQueryHelper<T> GetSimpleQueryHelperInstance()
17         {
18             switch (DataBaseEnginer)
19             {
20                 case "MySQL":
21                     return new MySqlSimpleQueryHelper<T>(TabelName);
22                 case "MSSQL":
23                     break;
24                 case "Oracle":
25                     break;
26                 default:
27                     break;
28             }
29             throw new NullReferenceException("the ISqlSimpleQueryHeper instance is not initialized!");
30         }
31 }

2、接口定义：

IDBAccess.cs

 1   public interface IDBAccess<T> where T : DBHelperModel, new()
 2     {
 3         /// <summary>
 4         /// 增加一条数据
 5         /// </summary>
 6          int AddModel(T model);
 7 
 8         /// <summary>
 9         /// 更新一条数据
10         /// </summary>
11         /// <param name="model"></param>
12         /// <returns></returns>
13          int UpdateModel(T model,string keyPropertyName);
14 
15         /// <summary>
16         /// 删除一条数据
17         /// </summary>
18          int DeleteByKey(object keyValue, string keyPropertyName);
19 
20         /// <summary>
21         /// 删除一些数据
22         /// </summary>
23          int DeleteWhere(string whereStr = null);
24 
25         List<T> GetModelList(string whereStr = null);
26 
27         List<T> GetModelList(out int count, string whereStr = null, int pageIndex = 1, int pageSize = 10, string orderColumn = null, string order = null);
28 
29         T GetModelByKey(object keyValue, string keyPropertyName);
30 
31         bool IsExist(object keyValue, string keyPropertyName);
32 
33         int GetCount(string strWhere = null);
34     }

3.最后的访问

DBAccesser

    public class DBAccess<T> : IDAL.IDBAccess<T> where T : DBHelperModel, new()
    {
        private readonly ISqlSimpleQueryHelper<T> QueryHelper = null;
        T model;
        public DBAccess()
        {
            model = new T();
            QueryHelper = new SqlQueryHelperBuilder<T>(model.TabelName).GetSimpleQueryHelperInstance();

        }
        public int AddModel(T model)
        {
            return QueryHelper.AddModel(model);
        }

        public int UpdateModel(T model, string keyPropertyName)
        {
            model.KeyPropertyName = keyPropertyName;
            return QueryHelper.UpdateModel(model, model.KeyPropertyColumnName);
        }

        public int DeleteByKey(object keyValue, string keyPropertyName)
        {
            model.KeyPropertyName = keyPropertyName;
            return QueryHelper.DeleteByParameter(model.KeyProperty.ParameterName, keyValue, model.KeyProperty.DbValueType);
        }

        public int DeleteWhere(string whereStr = null)
        {
            return QueryHelper.DeleteWhere(whereStr);
        }

        public List<T> GetModelList(string whereStr = null)
        {
            return QueryHelper.GetModelList(whereStr);
        }

        public List<T> GetModelList(out int count, string whereStr = null, int pageIndex = 1, int pageSize = 10, string orderColumn = null, string order = null)
        {
            return QueryHelper.GetPagedList(Count: out count, StrWhere: whereStr, PageIndex: pageIndex, PageSize: pageSize, Order: order, OrderColumn: orderColumn);
        }

        public T GetModelByKey(object keyValue, string keyPropertyName)
        {
            model.KeyPropertyName = keyPropertyName;
            return QueryHelper.GetModelByParameter(model.KeyProperty.ParameterName, keyValue, model.KeyProperty.DbValueType);
        }

        public bool IsExist(object keyValue, string keyPropertyName)
        {
            model.KeyPropertyName = keyPropertyName;
            return QueryHelper.IsExist(model.KeyProperty.ParameterName, keyValue, model.KeyProperty.DbValueType);
        }

        public int GetCount(string strWhere = null)
        {
            return QueryHelper.GetCount(strWhere);
        }
    }

例：

static void Main(string[] args)
{
ST.EPolice.IDAL.IDBAccess<ST.EPolice.Model.Student> target = new ST.EPolice.DAL.DBAccess<ST.EPolice.Model.Student>();
ST.EPolice.Model.Student model = new ST.EPolice.Model.Student { StudentId = "001", Name = "lcn" }; // TODO: 初始化为适当的值
Console.WriteLine(target.AddModel(model));

Console.WriteLine(target.GetModelByKey(model.StudentId,"StudentId"));
Console.Read();
}