.NET中的缓存依赖的开启及使用(二)

在代码中使用缓存依赖(C#)。

(1)UserCacheDependency 类

public static class UserCacheDependency
{
	public static object GetCache(string CacheKey)
	{
		return HttpRuntime.Cache[CacheKey];
	}

	public static void SetCache(string CacheKey, object objObject, CacheDependency dep)
	{
		HttpRuntime.Cache.Insert(CacheKey, objObject, dep, Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration, CacheItemPriority.Normal, null);
	}

	public static object GetModelSqlCache(string CacheKey, SqlCacheDependency dep, Delegate dg, params object[] obj)
	{
		using (dep)
		{
			object cache = GetCache(CacheKey);
			if (cache == null)
			{
				cache = dg.DynamicInvoke(obj);
				if (cache != null)
				{
					SqlCacheDependency dependency = dep;
					SetCache(CacheKey, cache, dependency);
				}
			}
			return cache;
		}
	}

	public static DataSet GetSqlCache(string CacheKey, SqlCacheDependency dep, Delegate dg, params object[] obj)
	{
		using (dep)
		{
			object cache = GetCache(CacheKey);
			if (cache == null)
			{
				cache = dg.DynamicInvoke(obj);
				if (cache != null)
				{
					SqlCacheDependency dependency = dep;
					SetCache(CacheKey, cache, dependency);
				}
			}
			return (DataSet) cache;
		}
	}

	public static object GetSqlCache(string CacheKey, SqlCacheDependency dep, Delegate dg, int args)
	{
		using (dep)
		{
			object cache = GetCache(CacheKey);
			if (cache == null)
			{
				cache = dg.DynamicInvoke(new object[] { args });
				if (cache != null)
				{
					SqlCacheDependency dependency = dep;
					SetCache(CacheKey, cache, dependency);
				}
			}
			return cache;
		}
	}

	public static string[] GetSqlReturnValueCache(string CacheKey, SqlCacheDependency dep, Delegate dg, params object[] obj)
	{
		using (dep)
		{
			object cache = GetCache(CacheKey);
			if (cache == null)
			{
				cache = dg.DynamicInvoke(obj);
				if (cache != null)
				{
					SqlCacheDependency dependency = dep;
					SetCache(CacheKey, cache, dependency);
				}
			}
			return (string[]) cache;
		}
	}
}

(2)数据访问类

/// <summary>
/// 数据访问抽象基础类
/// </summary>
public abstract class DbHelperSQL
{
	//数据库连接字符串(web.config来配置)，多数据库可使用DbHelperSQLP来实现.
	public static string connectionString = PubConstant.ConnectionString;     		
	public DbHelperSQL()
	{            
	}

	/// <summary>
	/// 执行查询语句，返回SqlDataReader ( 注意：调用该方法后，一定要对SqlDataReader进行Close )
	/// </summary>
	/// <param name="strSQL">查询语句</param>
	/// <returns>SqlDataReader</returns>
	public static SqlDataReader ExecuteReader(string strSQL)
	{
		SqlConnection connection = new SqlConnection(connectionString);
		SqlCommand cmd = new SqlCommand(strSQL, connection);
		try
		{
			connection.Open();
			SqlDataReader myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
			return myReader;
		}
		catch (System.Data.SqlClient.SqlException e)
		{
			throw e;
		}   

	}
	
	/// <summary>
	/// 执行查询语句，返回DataSet
	/// </summary>
	/// <param name="SQLString">查询语句</param>
	/// <returns>DataSet</returns>
	public static DataSet Query(string SQLString)
	{
		using (SqlConnection connection = new SqlConnection(connectionString))
		{
			DataSet ds = new DataSet();
			try
			{
				connection.Open();
				SqlDataAdapter command = new SqlDataAdapter(SQLString, connection);
				command.Fill(ds, "ds");
			}
			catch (System.Data.SqlClient.SqlException ex)
			{
				throw new Exception(ex.Message);
			}
			return ds;
		}
	}
	#endregion

	#region 存储过程操作

	/// <summary>
	/// 执行存储过程，返回SqlDataReader ( 注意：调用该方法后，一定要对SqlDataReader进行Close )
	/// </summary>
	/// <param name="storedProcName">存储过程名</param>
	/// <param name="parameters">存储过程参数</param>
	/// <returns>SqlDataReader</returns>
	public static SqlDataReader RunProcedure(string storedProcName, IDataParameter[] parameters)
	{
		SqlConnection connection = new SqlConnection(connectionString);
		SqlDataReader returnReader;
		connection.Open();
		SqlCommand command = BuildQueryCommand(connection, storedProcName, parameters);
		command.CommandType = CommandType.StoredProcedure;
		returnReader = command.ExecuteReader(CommandBehavior.CloseConnection);
		return returnReader;
		
	}

	/// <summary>
	/// 执行存储过程
	/// </summary>
	/// <param name="storedProcName">存储过程名</param>
	/// <param name="parameters">存储过程参数</param>
	/// <param name="tableName">DataSet结果中的表名</param>
	/// <returns>DataSet</returns>
	public static DataSet RunProcedure(string storedProcName, IDataParameter[] parameters, string tableName)
	{
		using (SqlConnection connection = new SqlConnection(connectionString))
		{
			DataSet dataSet = new DataSet();
			connection.Open();
			SqlDataAdapter sqlDA = new SqlDataAdapter();
			sqlDA.SelectCommand = BuildQueryCommand(connection, storedProcName, parameters);
			sqlDA.Fill(dataSet, tableName);
			connection.Close();
			return dataSet;
		}
	}

	/// <summary>
	/// 构建 SqlCommand 对象(用来返回一个结果集，而不是一个整数值)
	/// </summary>
	/// <param name="connection">数据库连接</param>
	/// <param name="storedProcName">存储过程名</param>
	/// <param name="parameters">存储过程参数</param>
	/// <returns>SqlCommand</returns>
	private static SqlCommand BuildQueryCommand(SqlConnection connection, string storedProcName, IDataParameter[] parameters)
	{
		SqlCommand command = new SqlCommand(storedProcName, connection);
		command.CommandType = CommandType.StoredProcedure;
		foreach (SqlParameter parameter in parameters)
		{
			if (parameter != null)
			{
				// 检查未分配值的输出参数,将其分配以DBNull.Value.
				if ((parameter.Direction == ParameterDirection.InputOutput || parameter.Direction == ParameterDirection.Input) &&
					(parameter.Value == null))
				{
					parameter.Value = DBNull.Value;
				}
				command.Parameters.Add(parameter);
			}
		}

		return command;
	}

	/// <summary>
	/// 执行存储过程，返回影响的行数		
	/// </summary>
	/// <param name="storedProcName">存储过程名</param>
	/// <param name="parameters">存储过程参数</param>
	/// <param name="rowsAffected">影响的行数</param>
	/// <returns></returns>
	public static int RunProcedure(string storedProcName, IDataParameter[] parameters, out int rowsAffected)
	{
		using (SqlConnection connection = new SqlConnection(connectionString))
		{
			int result;
			connection.Open();
			SqlCommand command = BuildIntCommand(connection, storedProcName, parameters);
			rowsAffected = command.ExecuteNonQuery();
			result = (int)command.Parameters["ReturnValue"].Value;
			//Connection.Close();
			return result;
		}
	}

	/// <summary>
	/// 创建 SqlCommand 对象实例(用来返回一个整数值)	
	/// </summary>
	/// <param name="storedProcName">存储过程名</param>
	/// <param name="parameters">存储过程参数</param>
	/// <returns>SqlCommand 对象实例</returns>
	private static SqlCommand BuildIntCommand(SqlConnection connection, string storedProcName, IDataParameter[] parameters)
	{
		SqlCommand command = BuildQueryCommand(connection, storedProcName, parameters);
		command.Parameters.Add(new SqlParameter("ReturnValue",
			SqlDbType.Int, 4, ParameterDirection.ReturnValue,
			false, 0, 0, string.Empty, DataRowVersion.Default, null));
		return command;
	}
	#endregion

}

(3) 在代码中调用

delegate DataSet TopNewsListDelegate(int n);

public DataSet GetTopList(int n)
{
 SqlParameter[] parameters = new SqlParameter[] { new SqlParameter("@n", SqlDbType.Int, 4) };
 parameters[0].Value = n;
 return DbHelperSQL.RunProcedure("storedProcName", parameters, "table_name_in_dataset");
}

public DataSet GetTopListByCache(int n)
{
 SqlCacheDependency dep = new SqlCacheDependency("ilovhealth", "news");
 TopNewsListDelegate dg = new TopNewsListDelegate(this.GetTopList); 
 return (DataSet)UserCacheDependency.GetModelSqlCache("News_TOP_LIST", dep, dg, new object[] { n });
}