1.xxxx后台用到了两个设计模式，工厂模式和单体模式
先看看工厂模式public interface IDaoFactory抽象工厂，定义各种XXXDao GetXXXDao()方法。Dao是用来和数据库打交道的如：Save，update等等看看单体模式，在用Nhibernate操作数据库时
1 using System.Runtime.Remoting.Messaging; 2 using System.Web; 3 using NHibernate; 4 using NHibernate.Cache; 5 using NHibernate.Cfg; 6 using XXXX.Srm2008.Common.Util; 7 using NHibernate.Type; 8 using NHibernate.Id; 9 using System.Collections; 10 using NHibernate.Engine; 11 using NHibernate.Dialect; 12 using System.Data; 13 14 15 namespace Avon.Srm2008.Core 16 { 17 /// 18 /// Handles creation and management of sessions and transactions. It is a singleton because 19 /// building the initial session factory is very expensive. Inspiration for this class came 20 /// from Chapter 8 of Hibernate in Action by Bauer and King. Although it is a sealed singleton 21 /// you can use TypeMock (http://www.typemock.com) for more flexible testing. 22 /// 23 public sealed class NHibernateSessionManager 24 { 25 #region Thread-safe, lazy Singleton 26 27 /// 28 /// This is a thread-safe, lazy singleton. See http://www.yoda.arachsys.com/csharp/singleton.html 29 /// for more details about its implementation. 30 /// 31 public static NHibernateSessionManager Instance 32 { 33 get 34 { 35 return Nested.NHibernateSessionManager; 36 } 37 } 38 39 /// 40 /// Initializes the NHibernate session factory upon instantiation. 41 /// 42 private NHibernateSessionManager() 43 { 44 InitSessionFactory(); 45 } 46 47 /// 48 /// Assists with ensuring thread-safe, lazy singleton 49 /// 50 private class Nested 51 { 52 static Nested() { } 53 internal static readonly NHibernateSessionManager NHibernateSessionManager = new NHibernateSessionManager(); 54 } 55 56 #endregion 57 58 private void InitSessionFactory() 59 { 60 sessionFactory = new Configuration().Configure().BuildSessionFactory(); 61 } 62 63 /// 64 /// Allows you to register an interceptor on a new session. This may not be called if there is already 65 /// an open session attached to the HttpContext. If you have an interceptor to be used, modify 66 /// the HttpModule to call this before calling BeginTransaction(). 67 /// 68 public void RegisterInterceptor(IInterceptor interceptor) 69 { 70 ISession session = ContextSession; 71 72 if (session != null && session.IsOpen) 73 { 74 throw new CacheException("You cannot register an interceptor once a session has already been opened"); 75 } 76 77 GetSession(interceptor); 78 } 79 80 public ISession GetSession() 81 { 82 return GetSession(null); 83 } 84 85 /// 86 /// Gets a session with or without an interceptor. This method is not called directly; instead, 87 /// it gets invoked from other public methods. 88 /// 89 private ISession GetSession(IInterceptor interceptor) 90 { 91 ISession session = ContextSession; 92 93 if (session == null) 94 { 95 if (interceptor != null) 96 { 97 session = sessionFactory.OpenSession(interceptor); 98 } 99 else 100 { 101 session = sessionFactory.OpenSession(); 102 } 103 104 ContextSession = session; 105 } 106 107 CheckHelper.Ensure(session != null, "session was null"); 108 109 return session; 110 } 111 112 /// 113 /// Flushes anything left in the session and closes the connection. 114 /// 115 public void CloseSession() 116 { 117 ISession session = ContextSession; 118 119 if (session != null && session.IsOpen) 120 { 121 //session.Flush(); 122 session.Close(); 123 } 124 125 ContextSession = null; 126 } 127 128 public void BeginTransaction() 129 { 130 ITransaction transaction = ContextTransaction; 131 132 if (transaction == null) 133 { 134 transaction = GetSession().BeginTransaction(); 135 ContextTransaction = transaction; 136 } 137 } 138 139 public void CommitTransaction() 140 { 141 ITransaction transaction = ContextTransaction; 142 143 try 144 { 145 if (HasOpenTransaction()) 146 { 147 transaction.Commit(); 148 ContextTransaction = null; 149 } 150 } 151 catch (HibernateException) 152 { 153 RollbackTransaction(); 154 throw; 155 } 156 } 157 158 public bool HasOpenTransaction() 159 { 160 ITransaction transaction = ContextTransaction; 161 162 return transaction != null && !transaction.WasCommitted && !transaction.WasRolledBack; 163 } 164 165 public void RollbackTransaction() 166 { 167 ITransaction transaction = ContextTransaction; 168 169 try 170 { 171 if (HasOpenTransaction()) 172 { 173 transaction.Rollback(); 174 } 175 176 ContextTransaction = null; 177 } 178 finally 179 { 180 CloseSession(); 181 } 182 } 183 184 public object GetSequenceNextValue(IType type, string sequenceName) 185 { 186 SequenceGenerator seq = new SequenceGenerator(); 187 Hashtable param = new Hashtable(); 188 param.Add("sequence", sequenceName); 189 seq.Configure(type, param, new Oracle9Dialect()); 190 return seq.Generate((ISessionImplementor)GetSession(), null); 191 } 192 193 /// 194 /// If within a web context, this uses 198 private ITransaction ContextTransaction 199 { 200 get 201 { 202 if (IsInWebContext()) 203 { 204 return (ITransaction)HttpContext.Current.Items[TRANSACTION_KEY]; 205 } 206 else 207 { 208 return (ITransaction)CallContext.GetData(TRANSACTION_KEY); 209 } 210 } 211 set 212 { 213 if (IsInWebContext()) 214 { 215 HttpContext.Current.Items[TRANSACTION_KEY] = value; 216 } 217 else 218 { 219 CallContext.SetData(TRANSACTION_KEY, value); 220 } 221 } 222 } 223 224 /// 225 /// If within a web context, this uses 229 private ISession ContextSession 230 { 231 get 232 { 233 if (IsInWebContext()) 234 { 235 return (ISession)HttpContext.Current.Items[SESSION_KEY]; 236 } 237 else 238 { 239 return (ISession)CallContext.GetData(SESSION_KEY); 240 } 241 } 242 set 243 { 244 if (IsInWebContext()) 245 { 246 HttpContext.Current.Items[SESSION_KEY] = value; 247 } 248 else 249 { 250 CallContext.SetData(SESSION_KEY, value); 251 } 252 } 253 } 254 255 private bool IsInWebContext() 256 { 257 return HttpContext.Current != null; 258 } 259 260 private const string TRANSACTION_KEY = "CONTEXT_TRANSACTION"; 261 private const string SESSION_KEY = "CONTEXT_SESSION"; 262 private ISessionFactory sessionFactory; 263 } 264 }