问题
I am a newbie to 3 tier architecture and below is my DAL code
public static int Insert(string firstname, string lastname, DateTime dob, string gender,string email, string password)
{
// bool flag = false;
SqlParameter pid;
SqlParameter result;
SqlConnection con = Generic.DBConnection.OpenConnection();
try
{
SqlCommand cmd1 = new SqlCommand("Insertreg", con);
cmd1.CommandType = CommandType.StoredProcedure;
cmd1.Parameters.AddWithValue("@FirstName", firstname);
cmd1.Parameters.AddWithValue("@LastName", lastname);
cmd1.Parameters.AddWithValue("@Dob", dob);
cmd1.Parameters.AddWithValue("@Gender", gender);
cmd1.Parameters.AddWithValue("@EmailId", email);
cmd1.Parameters.AddWithValue("@Password", password);
result = cmd1.Parameters.Add("@result", System.Data.SqlDbType.Int);
result.Direction = System.Data.ParameterDirection.Output;
pid = cmd1.Parameters.Add("@id", System.Data.SqlDbType.Int);
pid.Direction = System.Data.ParameterDirection.Output;
return cmd1.ExecuteNonQuery();
con.Close();
}
catch (Exception ex)
{
throw ex;
}
}
this in BAL
public int insert(string firstname,string lastname,DateTime dob,string gender,string email,string password)
{
ProfileMasterDAL dal=new ProfileMasterDAL();
try
{
return ProfileMasterDAL.Insert(firstname, lastname, dob, gender,email, password);
}
catch (Exception ex)
{
throw ex;
}
finally
{
dal = null;
}
}
I my UI
ProfileMasterBLL pmBLL = new ProfileMasterBLL();
pmBLL.insert(firstname, lastname, dob, gender, mobile, country, state, email, password);
Is this the correct way to code in 3 tier??I mean how to call methods from DAL to BAL and into UI?If not suggest me some good way.Thanks.
回答1:
Normally I do the following:
- Define a Business Layer (BL, you call it BAL). This contains the definitions of you business entities. It also defines interfaces to retrieve/save/delete data for whatever patterns you use (repository, context, etc).
- Define a Data Access Layer (DAL). This contains the actual implementation for the retrieve/save/delete interfaces.
- Define a UI layer. This contains UI elements (forms, controls, models, controllers, etc), which can use the BL to load data.
The references are the following:
- The BL doesn't know the DAL or the UI.
- The DAL knows the BL. The DAL does not know the UI.
- THe UI knows the BL. The UI does not know the DAL.
The big question for you probably is, how does the BL retrieve/save/delete data when it doesn't know the DAL, and therefore cannot create an instance of a class in the DAL. Well, this is where a little Dependency Injection comes in handy. All you have to wire up is the injection of the DAL-class to the BL-interface.
Hope this makes sense. I use it as my standard 3-tier implementation, and it works absolutely without problems. Specifically, I use Entity Framework with POCO for entities, and the DI I use is a custom one, but any of the ones out there will do.
UPDATE
The BL does not know the DAL.
- The BL defines an interface (lets call it IRepository) which it can use to do what it needs to do.
- The DAL defines a class (Repository) which implements the interface IRepository. So the actual implementation of the repository is in the DAL.
- Obviously the BL cannot create an instance of the repository directly. This is where dependency injection comes in, this allows the developer to create an instance of a class where it normally cannot be done. A simple crude version of this, is to use reflection.
I hope this makes more sense.
回答2:
It might help you to see some actual code. I suggest you download NetTiers, run it against your db schema and see the outputted code for the implementation details.
回答3:
using System;
using System.Data;
using System.Configuration;
using System.Collections.Generic;
using System.Text;
using System.Data.Common;
using System.Data.SqlClient;
using System.Data.OleDb;
using System.Data.Odbc;
using System.IO;
using System.ComponentModel;
namespace dal
{
/// <summary>
/// Summary description for Data Access Layer
/// </summary>
public class DataAccess
{
public string strConnectionString;
private DbConnection objConnection;
private DbCommand objCommand;
private DbProviderFactory objFactory = null;
private bool boolHandleErrors=false;
private string strLastError;
private bool boolLogError=false;
private string strLogFile;
public DataAccess()
{
//strConnectionString = ;
strConnectionString = objCommon.GetConnectionString;
objFactory = OleDbFactory.Instance;
objConnection = objFactory.CreateConnection();
objCommand = objFactory.CreateCommand();
objConnection.ConnectionString = strConnectionString;
objCommand.Connection = objConnection;
}
public bool HandleErrors
{
get
{
return boolHandleErrors;
}
set
{
boolHandleErrors = value;
}
}
public string LastError
{
get
{
return strLastError;
}
}
public bool LogErrors
{
get
- {
return boolLogError;
}
set
{
boolLogError = value;
}
}
public string LogFile
{
get
{
return strLogFile;
}
set
{
strLogFile = value;
}
}
public int AddParameter(string name, object value)
{
DbParameter p = objFactory.CreateParameter();
p.ParameterName = name;
p.Value = value;
return objCommand.Parameters.Add(p);
}
public int AddParameter(string name, object value, ParameterDirection direction)
{
DbParameter p = objFactory.CreateParameter();
p.ParameterName = name;
p.Value = value;
p.Direction = direction;
return objCommand.Parameters.Add(p);
}
public int AddParameter(string name, object value, DbType type)
{
DbParameter p = objFactory.CreateParameter();
p.ParameterName = name;
p.Value = value;
p.DbType = type;
return objCommand.Parameters.Add(p);
}
public int AddParameter(DbParameter parameter)
{
return objCommand.Parameters.Add(parameter);
}
public DbCommand Command
{
get
{
return objCommand;
}
}
public void BeginTransaction()
{
try
{
if (objConnection.State == System.Data.ConnectionState.Closed)
{
objConnection.Open();
}
objCommand.Transaction = objConnection.BeginTransaction();
}
catch (Exception Ex)
{
HandleExceptions(Ex);
}
}
public void CommitTransaction()
{
objCommand.Transaction.Commit();
objConnection.Close();
}
public void RollbackTransaction()
{
objCommand.Transaction.Rollback();
objConnection.Close();
}
public int ExecuteNonQuery(string query)
{
return ExecuteNonQuery(query, CommandType.Text, ConnectionState.CloseOnExit);
}
public int ExecuteNonQuery(string query, CommandType commandtype)
{
return ExecuteNonQuery(query, commandtype, ConnectionState.CloseOnExit);
}
public int ExecuteNonQuery(string query, ConnectionState connectionstate)
{
return ExecuteNonQuery(query, CommandType.Text, connectionstate);
}
public int ExecuteNonQuery(string query, CommandType commandtype, ConnectionState connectionstate)
{
objCommand.CommandText = query;
objCommand.CommandType = commandtype;
int i = -1;
try
{
if (objConnection.State == System.Data.ConnectionState.Closed)
{
objConnection.Open();
}
i = objCommand.ExecuteNonQuery();
}
catch (Exception ex)
{
HandleExceptions(ex);
}
finally
{
objCommand.Parameters.Clear();
if (connectionstate == ConnectionState.CloseOnExit)
{
objConnection.Close();
}
}
return i;
}
public object ExecuteScalar(string query)
{
return ExecuteScalar(query, CommandType.Text, ConnectionState.CloseOnExit);
}
public object ExecuteScalar(string query, CommandType commandtype)
{
return ExecuteScalar(query, commandtype, ConnectionState.CloseOnExit);
}
public object ExecuteScalar(string query, ConnectionState connectionstate)
{
return ExecuteScalar(query, CommandType.Text, connectionstate);
}
public object ExecuteScalar(string query, CommandType commandtype, ConnectionState connectionstate)
{
objCommand.CommandText = query;
objCommand.CommandType = commandtype;
object o = null;
try
{
if (objConnection.State == System.Data.ConnectionState.Closed)
{
objConnection.Open();
}
o = objCommand.ExecuteScalar();
}
catch (Exception ex)
{
HandleExceptions(ex);
}
finally
{
objCommand.Parameters.Clear();
if (connectionstate == ConnectionState.CloseOnExit)
{
objConnection.Close();
}
}
return o;
}
public DbDataReader ExecuteReader(string query)
{
return ExecuteReader(query, CommandType.Text, ConnectionState.CloseOnExit);
}
public DbDataReader ExecuteReader(string query, CommandType commandtype)
{
return ExecuteReader(query, commandtype, ConnectionState.CloseOnExit);
}
public DbDataReader ExecuteReader(string query, ConnectionState connectionstate)
{
return ExecuteReader(query, CommandType.Text, connectionstate);
}
public DbDataReader ExecuteReader(string query, CommandType commandtype, ConnectionState connectionstate)
{
objCommand.CommandText = query;
objCommand.CommandType = commandtype;
DbDataReader reader = null;
try
{
if (objConnection.State == System.Data.ConnectionState.Closed)
{
objConnection.Open();
}
if (connectionstate == ConnectionState.CloseOnExit)
{
reader = objCommand.ExecuteReader(CommandBehavior.CloseConnection);
}
else
{
reader = objCommand.ExecuteReader();
}
}
catch (Exception ex)
{
HandleExceptions(ex);
}
finally
{
objCommand.Parameters.Clear();
}
return reader;
}
public DataSet ExecuteDataSet(string query)
{
return ExecuteDataSet(query, CommandType.Text, ConnectionState.CloseOnExit);
}
public DataSet ExecuteDataSet(string query, CommandType commandtype)
{
return ExecuteDataSet(query, commandtype, ConnectionState.CloseOnExit);
}
public DataSet ExecuteDataSet(string query, ConnectionState connectionstate)
{
return ExecuteDataSet(query, CommandType.Text, connectionstate);
}
public DataSet ExecuteDataSet(string query, CommandType commandtype, ConnectionState connectionstate)
{
DbDataAdapter adapter = objFactory.CreateDataAdapter();
objCommand.CommandText = query;
objCommand.CommandType = commandtype;
adapter.SelectCommand = objCommand;
DataSet ds = new DataSet();
try
{
adapter.Fill(ds);
}
catch (Exception ex)
{
HandleExceptions(ex);
}
finally
{
objCommand.Parameters.Clear();
if (connectionstate == ConnectionState.CloseOnExit)
{
if (objConnection.State == System.Data.ConnectionState.Open)
{
objConnection.Close();
}
}
}
return ds;
}
private void HandleExceptions(Exception ex)
{
throw ex;
}
private void WriteToLog(string msg)
{
StreamWriter writer = File.AppendText(LogFile);
writer.WriteLine(DateTime.Now.ToString() + " - " + msg);
writer.Close();
}
public void Dispose()
{
objConnection.Close();
objConnection.Dispose();
objCommand.Dispose();
}
public enum Providers
{
SqlServer, OleDb, Oracle, ODBC, ConfigDefined
}
public enum ConnectionState
{
KeepOpen, CloseOnExit
}
public interface ILoadFromDataRow
{
bool LoadFromDataRow(DataRow row);
}
}
}
回答4:
You can you the following sample code for 3 tier architecture :-
CLASS - BAL.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Collections;
public class BAL
{
DAL objDAL;
public BAL()
{
}
public string _Name;
public string Name
{
get { return _Name; }
set { _Name = value; }
}
public int insert()
{
objDAL = new DAL();
int val = 0;
try
{
Hashtable objHash = new Hashtable();
objHash.Add("@Name", Convert.ToString(_Name));
val = objDAL.Insert("Your SP Name", objHash);
}
catch (Exception ex)
{
throw ex;
}
finally
{
objDAL = null;
}
return val;
}
}
CLASS - DAL.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data;
using System.Data.SqlClient;
using System.Collections;
public class DAL : IDisposable
{
SqlConnection con;
public DAL()
{
con = new SqlConnection("Connection String");
}
public int Insert(string CMD, Hashtable objHash)
{
int val = 0;
try
{
SqlCommand cmd1 = new SqlCommand(CMD, con);
cmd1.CommandType = CommandType.StoredProcedure;
foreach (DictionaryEntry de in objHash)
{
cmd1.Parameters.AddWithValue(Convert.ToString(de.Key), Convert.ToString(de.Value));
}
con.Open();
val = cmd1.ExecuteNonQuery();
}
catch (Exception ex)
{
throw ex;
}
finally
{
con.Close();
}
return val;
}
#region IDisposable Members
public void Dispose()
{
throw new NotImplementedException();
}
#endregion
}
UI:-
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class _Default : System.Web.UI.Page
{
BAL objBAL;
protected void Page_Load(object sender, EventArgs e)
{
Insert();
}
public void Insert()
{
int val = 0;
objBAL = new BAL();
objBAL.Name = "stackoverflow";
try
{
val = objBAL.insert();
}
catch { }
finally
{
objBAL = null;
}
if (val != 0)
{
//Insert sucessful
}
else
{
//Error in Insert.
}
}
}
来源：https://stackoverflow.com/questions/12214371/use-of-bal-in-3-tier-architecturehow-to-call-methods-from-dal-to-bal