#region Licence
/*
* Copyright 2002-2007 the original author or authors.
*
* 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
using System;
using System.Collections;
using System.Data;
using Common.Logging;
using Spring.Collections;
using Spring.Dao;
using Spring.Objects.Factory;
using Spring.Threading;
namespace Spring.Data.Common{
/// <summary>
/// A wrapper implementation for IDbProvider such that multiple DbProvider instances can be
/// selected at runtime, say based on web request criteria.
/// </summary>
/// <remarks>
/// The name of which DbProvider to use, as provided to the IDictionary property TargetDbProviders
/// is "dbProviderName". Once the target dbprovider name is known, set the name via a call to
/// <code>LogicalThreadContext.SetData(MultiDelegatingDbProvider.CURRENT_DBPROVIDER_SLOTNAME, "database1ProviderName")</code>. The value
/// "database1ProviderName" must match a key in the provided TargetDbProviders dictionary.
/// </remarks>
/// <author>Mark Pollack</author>
public class MultiDelegatingDbProvider : IDbProvider, IInitializingObject
{
public static readonly string CURRENT_DBPROVIDER_SLOTNAME = Spring.Util.UniqueKey.GetTypeScopedString(typeof(MultiDelegatingDbProvider), "Current");
private IDbProvider defaultDbProvider;
private IDictionary targetDbProviders = new SynchronizedHashtable();
#region Logging Definition
private static readonly ILog LOG = LogManager.GetLogger(typeof(MultiDelegatingDbProvider));
#endregion
#region Constructors
/// <summary>
/// Initializes a new instance of the <see cref="MultiDelegatingDbProvider"/> class.
/// </summary>
public MultiDelegatingDbProvider()
{
}
/// <summary>
/// Initializes a new instance of the <see cref="MultiDelegatingDbProvider"/> class.
/// </summary>
/// <param name="targetDbProviders">The target db providers.</param>
public MultiDelegatingDbProvider(IDictionary targetDbProviders)
{
this.targetDbProviders = targetDbProviders;
}
#endregion
/// <summary>
/// Sets the default IDbProvider. This will be returned if no DbProvider is found in thread local storage.
/// </summary>
/// <value>The default db provider.</value>
public IDbProvider DefaultDbProvider
{
set { defaultDbProvider = value; }
}
/// <summary>
/// Sets the target db providers.
/// </summary>
/// <value>The target db providers.</value>
public IDictionary TargetDbProviders
{
set { targetDbProviders = value; }
}
/// <summary>
/// Ensures that the there are values in the TargetDbProviders dictionary and that the
/// key is of the type string and value is of the type IDbProvider.
/// </summary>
/// <exception cref="ArgumentException">If the above conditions are not met.</exception>
public void AfterPropertiesSet()
{
if (targetDbProviders.Count == 0)
{
throw new ArgumentException("Target DbProvider collection required.");
}
foreach (DictionaryEntry entry in targetDbProviders)
{
if (! entry.Key.GetType().Equals(typeof(string)))
{
throw new ArgumentException("Key identifying target IDbProvider in TargetDbProviders dictionary property is required to be of type string. Key = [" + entry.Key + "], type = [" + entry.Key.GetType() + "]");
}
IDbProvider targetProvider = entry.Value as IDbProvider;
if (targetProvider == null)
{
throw new ArgumentException("Value in TargetDbProviders dictionary is not of type IDbProvider. Type = [" + entry.Value.GetType() + "]");
}
}
}
#region IDbProvider methods
/// <summary>
/// Returns a new command object for executing SQL statments/Stored Procedures
/// against the database.
/// </summary>
/// <returns>An new <see cref="IDbCommand"/></returns>
public IDbCommand CreateCommand()
{
return GetTargetProvider().CreateCommand();
}
/// <summary>
/// Returns a new connection object to communicate with the database.
/// </summary>
/// <returns>A new <see cref="IDbConnection"/></returns>
public IDbConnection CreateConnection()
{
return GetTargetProvider().CreateConnection();
}
/// <summary>
/// Returns a new parameter object for binding values to parameter
/// placeholders in SQL statements or Stored Procedure variables.
/// </summary>
/// <returns>A new <see cref="IDbDataParameter"/></returns>
public IDbDataParameter CreateParameter()
{
return GetTargetProvider().CreateParameter();
}
/// <summary>
/// Returns a new adapter objects for use with offline DataSets.
/// </summary>
/// <returns>A new <see cref="IDbDataAdapter"/></returns>
public IDbDataAdapter CreateDataAdapter()
{
return GetTargetProvider().CreateDataAdapter();
}
/// <summary>
/// Returns a new instance of the providers CommandBuilder class.
/// </summary>
/// <returns>A new Command Builder</returns>
/// <remarks>In .NET 1.1 there was no common base class or interface
/// for command builders, hence the return signature is object to
/// be portable (but more loosely typed) across .NET 1.1/2.0</remarks>
public object CreateCommandBuilder()
{
return GetTargetProvider().CreateDataAdapter();
}
/// <summary>
/// Creates the name of the parameter in the format appropriate to use inside IDbCommand.CommandText.
/// </summary>
/// <param name="name">The unformatted name of the parameter.</param>
/// <returns>
/// The parameter name formatted foran IDbCommand.CommandText.
/// </returns>
/// <remarks>In most cases this adds the parameter prefix to the name passed into this method.</remarks>
public string CreateParameterName(string name)
{
return GetTargetProvider().CreateParameterName(name);
}
/// <summary>
/// Creates the name ofthe parameter in the format appropriate for an IDataParameter, i.e. to be
/// part of a IDataParameterCollection.
/// </summary>
/// <param name="name">The unformatted name of the parameter.</param>
/// <returns>
/// The parameter name formatted for an IDataParameter
/// </returns>
public string CreateParameterNameForCollection(string name)
{
return GetTargetProvider().CreateParameterNameForCollection(name);
}
/// <summary>
/// Return metadata information about the database provider
/// </summary>
/// <value></value>
public IDbMetadata DbMetadata
{
get { return GetTargetProvider().DbMetadata; }
}
/// <summary>
/// Connection string used to create connections.
/// </summary>
/// <value></value>
public string ConnectionString
{
get { return GetTargetProvider().ConnectionString; }
set { GetTargetProvider().ConnectionString = value; }
}
/// <summary>
/// Extracts the provider specific error code as a string.
/// </summary>
/// <param name="e">The data access exception.</param>
/// <returns>The provider specific error code</returns>
public string ExtractError(Exception e)
{
return GetTargetProvider().ExtractError(e);
}
/// <summary>
/// Determines whether the provided exception is in fact related
/// to database access. This can be provider dependent in .NET 1.1 since
/// there isn't a common base class for ADO.NET exceptions.
/// </summary>
/// <param name="e">The exception thrown when performing data access
/// operations.</param>
/// <returns>
/// <c>true</c> if is a valid data access exception for the specified
/// exception; otherwise, <c>false</c>.
/// </returns>
public bool IsDataAccessException(Exception e)
{
#if NET_2_0
if (e is System.Data.Common.DbException)
{
return true;
}
else
{
return false;
}
#else
return IsDataAccessExceptionBCL11(e);
#endif
}
/// <summary>
/// Determines whether is data access exception in .NET 1.1 for the specified exception.
/// </summary>
/// <param name="e">The candidate exception.</param>
/// <returns>
/// <c>true</c> if is data access exception in .NET 1.1 for the specified exception; otherwise, <c>false</c>.
/// </returns>
public bool IsDataAccessExceptionBCL11(Exception e)
{
return false;
}
#endregion
/// <summary>
/// Gets the target provider based on the thread local name "dbProviderName"
/// </summary>
/// <returns>The corresonding IDbProvider.</returns>
protected virtual IDbProvider GetTargetProvider()
{
string dbProviderName = (string)LogicalThreadContext.GetData(CURRENT_DBPROVIDER_SLOTNAME);
if (dbProviderName != null && targetDbProviders.Contains(dbProviderName))
{
return (IDbProvider)targetDbProviders[dbProviderName];
}
//Fall back to default if available
if (defaultDbProvider != null)
{
if (LOG.IsDebugEnabled)
{
LOG.Debug("No DbProvider defined in thread local storage, falling back to use DefaultDbProvider.");
}
return defaultDbProvider;
}
if (dbProviderName == null)
{
throw new InvalidDataAccessApiUsageException(
"No provider name found in thread local storage. Consider setting the property DefaultDbProvider to fallback to a default value.");
}
throw new InvalidDataAccessApiUsageException("'" + dbProviderName + "'"
+ " was not under the thread local key 'dbProviderName' and no default IDbProvider was set.");
}
/// <summary>
/// Convenience method to sets the name of the DbProvider that will be used for the
/// the current thread's procesing.
/// </summary>
/// <value>The name of the DbProvider to use for the current threads processing.</value>
public static string CurrentDbProviderName
{
set
{
LogicalThreadContext.SetData(CURRENT_DBPROVIDER_SLOTNAME, value);
}
}
}
}
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