DaoProxy.cs :  » Persistence-Frameworks » iBATIS.NET » IBatisNet » DataAccess » Configuration » C# / CSharp Open Source

#region Apache Notice
/*****************************************************************************
 * $Header: $
 * $Revision: 383115 $
 * $Date: 2006-03-04 15:21:51 +0100 (sam., 04 mars 2006) $
 * 
 * iBATIS.NET Data Mapper
 * Copyright (C) 2004 - Gilles Bayon
 *  
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 ********************************************************************************/
#endregion

#region Imports

using System;
using System.Collections;
using System.Reflection;
using Castle.DynamicProxy;
using IBatisNet.Common.Logging;
using IBatisNet.DataAccess.Exceptions;
using IBatisNet.DataAccess.Interfaces;

#endregion

namespace IBatisNet.DataAccess.Configuration{
  /// <summary>
  /// Summary description for DaoProxy.
  /// </summary>
  [CLSCompliant(false)]
  public class DaoProxy : IInterceptor  
  {
    #region Fields
    private static ArrayList _passthroughMethods = new ArrayList();
    private Dao _daoImplementation;
    private static readonly ILog _logger = LogManager.GetLogger( MethodBase.GetCurrentMethod().DeclaringType );
    #endregion

    #region Constructor (s) / Destructor
    /// <summary>
    /// Constructor for a DaoProxy
    /// </summary>
    static DaoProxy()
    {
      _passthroughMethods.Add("GetType");
      _passthroughMethods.Add("ToString");
    }

    /// <summary>
    /// Create a new proxy for the Dao
    /// </summary>
    /// <param name="dao">The dao object to proxy</param>
    public DaoProxy(Dao dao)
    {
      _daoImplementation = dao;
    }
    #endregion

    #region Methods
    /// <summary>
    /// 
    /// </summary>
    /// <param name="dao"></param>
    /// <returns></returns>
    public static IDao NewInstance(Dao dao) 
    {
      ProxyGenerator proxyGenerator = new ProxyGenerator();
      IInterceptor handler = new DaoProxy(dao);
      Type[] interfaces = {dao.DaoInterface, typeof(IDao)};

      return (proxyGenerator.CreateProxy(interfaces, handler, dao.DaoInstance) as IDao);
    }
    #endregion

    #region IInterceptor menbers

    /// <summary>
    /// 
    /// </summary>
    /// <param name="invocation"></param>
    /// <param name="arguments"></param>
    /// <returns></returns>
    public object Intercept(IInvocation invocation, params object[] arguments)
    {
      Object result = null;

      #region Logging
      if (_logger.IsDebugEnabled) 
      {
        _logger.Debug("Dao Proxy call to " + invocation.Method.Name);
      }
      #endregion

      if (_passthroughMethods.Contains(invocation.Method.Name)) 
      {
        try 
        {
          result = invocation.Method.Invoke( _daoImplementation.DaoInstance, arguments);
        } 
        catch (Exception e) 
        {
          throw UnWrapException(e, invocation.Method.Name);
        }
      } 
      else 
      {
        DaoManager daoManager = _daoImplementation.DaoManager;
        if ( daoManager.IsDaoSessionStarted() ) 
        {
          try 
          {
            result = invocation.Method.Invoke(_daoImplementation.DaoInstance, arguments);
          } 
          catch (Exception e) 
          {
            throw UnWrapException(e, invocation.Method.Name);
          }
        } 
        else 
        {
          #region Logging
          if (_logger.IsDebugEnabled) 
          {
            _logger.Debug("Dao Proxy, Open a connection ");
          }
          #endregion
          // Open a connection
          try 
          {
            daoManager.OpenConnection();
            result = invocation.Method.Invoke(_daoImplementation.DaoInstance, arguments);
          } 
          catch (Exception e) 
          {
            throw UnWrapException(e, invocation.Method.Name);
          } 
          finally 
          {
            daoManager.CloseConnection();
          }
        }
      }

      #region Logging
      if (_logger.IsDebugEnabled) 
      {
        _logger.Debug("End of proxyfied call to " + invocation.Method.Name);
      }
      #endregion

      return result;
    }

    private Exception UnWrapException(Exception ex, string methodName) 
    {
      Exception e = ex;
      while (true) 
      {
        if (typeof(DataAccessException).IsInstanceOfType(e))
        {
          return e;
        }
        else if (e.InnerException != null)
        {
          e = e.InnerException;
        }
        else
        {
          e = new DataAccessException( string.Format("DaoProxy : unable to intercept method name '{0}', cause : {1}", methodName, e.Message), e);
        }      
      }
    }

    #endregion


  }
}