一步一步打造3层架构在线电影网站！（3）系统设计

前面讨论了数据库部分地设计和实现，现在开始真正的用C#编码了。

这里我都是将设计和实现结合在一起写的，从层次结构上来说应该更加清晰吧。
4、          核心代码设计
核心代码主要是封装一些公用的功能，以后的数据层，商务层代码会继承核心代码，并且统一利用核心代码所提供的功能。核心代码类是抽象类，不可以实例化得。

Coofucoo.Core.DbObject：此类是所有数据层类得基类

using System;
using System.Data;
using System.Data.SqlClient;

namespace Coofucoo.Core
{
 /// <summary>
 /// DbObject is the class from which all classes in the Data Services
 /// Tier inherit. The core functionality of establishing a connection
 /// with the database and executing simple stored procedures is also
 /// provided by this base class.
 /// </summary>
 public abstract class DbObject
 {
  protected SqlConnection Connection;
  private string connectionString;

  /// <summary>
  /// A parameterized constructor, it allows us to take a connection
  /// string as a constructor argument, automatically instantiating
  /// a new connection.
  /// </summary>
  /// <param name="newConnectionString">Connection String to the associated database</param>
  public DbObject( string newConnectionString )
  {
   connectionString = newConnectionString;
   Connection = new SqlConnection( connectionString );
  }

  /// <summary>
  /// Protected property that exposes the connection string
  /// to inheriting classes. Read-Only.
  /// </summary>
  protected string ConnectionString
  {
   get
   {
    return connectionString;
   }
  }

  /// <summary>
  /// Private routine allowed only by this base class, it automates the task
  /// of building a SqlCommand object designed to obtain a return value from
  /// the stored procedure.
  /// </summary>
  /// <param name="storedProcName">Name of the stored procedure in the DB, eg. sp_DoTask</param>
  /// <param name="parameters">Array of IDataParameter objects containing parameters to the stored proc</param>
  /// <returns>Newly instantiated SqlCommand instance</returns>
  private SqlCommand BuildIntCommand(string storedProcName, IDataParameter[] parameters)
  {
   SqlCommand command = BuildQueryCommand( storedProcName, parameters );   

   command.Parameters.Add( new SqlParameter ( "ReturnValue",
    SqlDbType.Int,
    4, /* Size */
    ParameterDirection.ReturnValue,
    false, /* is nullable */
    0, /* byte precision */
    0, /* byte scale */
    string.Empty,
    DataRowVersion.Default,
    null ));

   return command;
  }

  /// <summary>
  /// Builds a SqlCommand designed to return a SqlDataReader, and not
  /// an actual integer value.
  /// </summary>
  /// <param name="storedProcName">Name of the stored procedure</param>
  /// <param name="parameters">Array of IDataParameter objects</param>
  /// <returns></returns>
  private SqlCommand BuildQueryCommand(string storedProcName, IDataParameter[] parameters)
  {
   SqlCommand command = new SqlCommand( storedProcName, Connection );
   command.CommandType = CommandType.StoredProcedure;

   foreach (SqlParameter parameter in parameters)
   {
    command.Parameters.Add( parameter );
   }

   return command;

  }

  /// <summary>
  /// Runs a stored procedure, can only be called by those classes deriving
  /// from this base. It returns an integer indicating the return value of the
  /// stored procedure, and also returns the value of the RowsAffected aspect
  /// of the stored procedure that is returned by the ExecuteNonQuery method.
  /// </summary>
  /// <param name="storedProcName">Name of the stored procedure</param>
  /// <param name="parameters">Array of IDataParameter objects</param>
  /// <param name="rowsAffected">Number of rows affected by the stored procedure.</param>
  /// <returns>An integer indicating return value of the stored procedure</returns>
  protected int RunProcedure(string storedProcName, IDataParameter[] parameters, out int rowsAffected )
  {
   int result;

   Connection.Open();
   SqlCommand command = BuildIntCommand( storedProcName, parameters );
   rowsAffected = command.ExecuteNonQuery();
   result = (int)command.Parameters["ReturnValue"].Value;
   Connection.Close();
   return result;
  }

  /// <summary>
  /// Will run a stored procedure, can only be called by those classes deriving
  /// from this base. It returns a SqlDataReader containing the result of the stored
  /// procedure.
  /// </summary>
  /// <param name="storedProcName">Name of the stored procedure</param>
  /// <param name="parameters">Array of parameters to be passed to the procedure</param>
  /// <returns>A newly instantiated SqlDataReader object</returns>
  protected SqlDataReader RunProcedure(string storedProcName, IDataParameter[] parameters )
  {
   SqlDataReader returnReader;

   Connection.Open();
   SqlCommand command = BuildQueryCommand( storedProcName, parameters );
   command.CommandType = CommandType.StoredProcedure;

   returnReader = command.ExecuteReader();
   //Connection.Close();
   return returnReader;
  }

  /// <summary>
  /// Creates a DataSet by running the stored procedure and placing the results
  /// of the query/proc into the given tablename.
  /// </summary>
  /// <param name="storedProcName"></param>
  /// <param name="parameters"></param>
  /// <param name="tableName"></param>
  /// <returns></returns>
  protected DataSet RunProcedure(string storedProcName, IDataParameter[] parameters, string tableName )
  {
   DataSet dataSet = new DataSet();
   Connection.Open();
   SqlDataAdapter sqlDA = new SqlDataAdapter();
   sqlDA.SelectCommand = BuildQueryCommand( storedProcName, parameters );
   sqlDA.Fill( dataSet, tableName );
   Connection.Close();

   return dataSet;
  }

  /// <summary>
  /// Takes an -existing- dataset and fills the given table name with the results
  /// of the stored procedure.
  /// </summary>
  /// <param name="storedProcName"></param>
  /// <param name="parameters"></param>
  /// <param name="dataSet"></param>
  /// <param name="tableName"></param>
  /// <returns></returns>
  protected void RunProcedure(string storedProcName, IDataParameter[] parameters, DataSet dataSet, string tableName )
  {
   Connection.Open();
   SqlDataAdapter sqlDA = new SqlDataAdapter();
   sqlDA.SelectCommand = BuildIntCommand( storedProcName, parameters );
   sqlDA.Fill( dataSet, tableName );
   Connection.Close();   
  }

 }
}

Coofucoo.Core.BizObject：商务层类得基类，无任何内容，以后可以添加。

using System;

namespace Coofucoo.Core
{
 /// <summary>
 /// The class from which all classes in the business tier
 /// inherit from.
 /// </summary>
 public class BizObject
 {
  public BizObject()
  {     
  }
 }
}

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