NHibernate系列文章三：简单的增删改查询

摘要

上一篇文章只完成了简单的NHibernate安装、配置和连接数据库。这篇文章介绍怎样实现最简单的数据库读写操作。

1. 重构ISessionFactory生成过程

将生成ISessionFactory的代码从main函数中移除，变成使用属性控制。

 1         private static ISessionFactory _sessionFactory;
 2 
 3         public static ISessionFactory SessionFactory
 4         {
 5             get
 6             {
 7                 if (_sessionFactory == null)
 8                 {
 9                     var cfg = new Configuration();
10 
11                     cfg.DataBaseIntegration(x =>
12                     {
13                         x.ConnectionString = "Data Source=localhost;Initial Catalog=NHibernateDemoDB;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
14                         x.Driver<SqlClientDriver>();
15                         x.Dialect<MsSql2008Dialect>();
16                     });
17                     cfg.AddAssembly(Assembly.GetExecutingAssembly());
18                     _sessionFactory = cfg.BuildSessionFactory();
19                 }
20                 return _sessionFactory;
21             }
22         }

SessionFactory的创建很占用系统资源，一般在整个应用程序中只创建一次。因此，这里通过判断if (_sessionFactory == null)实现一个最简单的单例模式。

2. GetAll和GetById函数代码

 1         private static IList<Customer> GetAll()
 2         {
 3             using (var session = SessionFactory.OpenSession())
 4             {
 5                 IList<Customer> list = session.CreateCriteria<Customer>().List<Customer>();
 6                 return list;
 7             }
 8         }
 9 
10         private static Customer GetById(int id)
11         {
12             using (var session = SessionFactory.OpenSession())
13             {
14                 Customer customer = session.Get<Customer>(id);
15                 return customer;
16             }
17         }

使用using子句，在using代码块完成后，将自动调用ISession的Dispose方法关闭Session

3. 增删改函数代码

 1         private static int Insert(Customer customer)
 2         {
 3             using (var session = SessionFactory.OpenSession())
 4             {
 5                 var identifier = session.Save(customer);
 6                 session.Flush();
 7                 return Convert.ToInt32(identifier);
 8             }
 9         }
10 
11         private static void Update(Customer customer)
12         {
13             using (var session = SessionFactory.OpenSession())
14             {
15                 session.SaveOrUpdate(customer);
16                 session.Flush();
17             }
18         }
19 
20         private static void Delete(int id)
21         {
22             using (var session = SessionFactory.OpenSession())
23             {
24                 var customer = session.Load<Customer>(id);
25                 session.Delete(customer);
26                 session.Flush();
27             }
28         }

session.Save: 插入新记录，返回新纪录主键值
session.SaveOrUpdate: 如果被调用的Customer对象在数据库里不存在（新记录），则插入新记录，否则修改该记录
session.Delete: 传入Customer对象进行删除
增删改操作完成之后需要调用session.Flush()方法，将对象持久化写入数据库。如果不调用此方法，方法结束后修改记录不能写入到数据库

4. 添加方法CreateCustomer

 1         private static Customer CreateCustomer()
 2         {
 3             var customer = new Customer
 4             {
 5                 FirstName = "Daniel",
 6                 LastName = "Tang",
 7                 Points = 100,
 8                 HasGoldStatus = true,
 9                 MemberSince = new DateTime(2012, 1, 1),
10                 CreditRating = CustomerCreditRating.Good,
11                 AverageRating = 42.42424242,
12                 Street = "123 Somewhere Avenue",
13                 City = "Nowhere",
14                 Province = "Alberta",
15                 Country = "Canada"
16             };
17             
18             return customer;
19         }

5. 修改main函数

 1         static void Main(string[] args)
 2         {
 3             Customer newCustomer = CreateCustomer();
 4             int customerId = Insert(newCustomer);
 5             Console.WriteLine("new customer id: {0}", customerId);
 6 
 7             IList<Customer> list = GetAll();
 8             Console.WriteLine("customer list count: {0}", list.Count);
 9             foreach(var item in list)
10             {
11                 Console.WriteLine("{0} {1}", item.FirstName, item.LastName);
12             }
13 
14             var customer = GetById(customerId);
15             Console.WriteLine("GetById: {0} {1}", customer.FirstName, customer.LastName);
16 
17             customer.LastName = "Chen";
18             Update(customer);
19             var updatedCustomer = GetById(customerId);
20             Console.WriteLine("updated: {0} {1}", updatedCustomer.FirstName, updatedCustomer.LastName);
21 
22             Delete(customerId);
23             var existedCustomer = GetById(customerId);
24             Console.WriteLine("after deleted: existing: {0}", existedCustomer != null);
25 
26             Console.ReadLine();
27         }

6. 完整的代码

  1 using NHibernate;
  2 using NHibernate.Cfg;
  3 using NHibernate.Dialect;
  4 using NHibernate.Driver;
  5 using System;
  6 using System.Collections.Generic;
  7 using System.Reflection;
  8 
  9 namespace NHibernateDemoApp
 10 {
 11     class Program
 12     {
 13         private static ISessionFactory _sessionFactory;
 14 
 15         public static ISessionFactory SessionFactory
 16         {
 17             get
 18             {
 19                 if (_sessionFactory == null)
 20                 {
 21                     var cfg = new Configuration();
 22 
 23                     cfg.DataBaseIntegration(x =>
 24                     {
 25                         x.ConnectionString = "Data Source=localhost;Initial Catalog=NHibernateDemoDB;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
 26                         x.Driver<SqlClientDriver>();
 27                         x.Dialect<MsSql2008Dialect>();
 28                     });
 29                     cfg.AddAssembly(Assembly.GetExecutingAssembly());
 30                     _sessionFactory = cfg.BuildSessionFactory();
 31                 }
 32                 return _sessionFactory;
 33             }
 34         }
 35 
 36         static void Main(string[] args)
 37         {
 38             Customer newCustomer = CreateCustomer();
 39             int customerId = Insert(newCustomer);
 40             Console.WriteLine("new customer id: {0}", customerId);
 41 
 42             IList<Customer> list = GetAll();
 43             Console.WriteLine("customer list count: {0}", list.Count);
 44             foreach(var item in list)
 45             {
 46                 Console.WriteLine("{0} {1}", item.FirstName, item.LastName);
 47             }
 48 
 49             var customer = GetById(customerId);
 50             Console.WriteLine("GetById: {0} {1}", customer.FirstName, customer.LastName);
 51 
 52             customer.LastName = "Chen";
 53             Update(customer);
 54             var updatedCustomer = GetById(customerId);
 55             Console.WriteLine("updated: {0} {1}", updatedCustomer.FirstName, updatedCustomer.LastName);
 56 
 57             Delete(customerId);
 58             var existedCustomer = GetById(customerId);
 59             Console.WriteLine("after deleted: existing: {0}", existedCustomer != null);
 60 
 61             Console.ReadLine();
 62         }
 63 
 64         private static Customer CreateCustomer()
 65         {
 66             var customer = new Customer
 67             {
 68                 FirstName = "Daniel",
 69                 LastName = "Tang",
 70                 Points = 100,
 71                 HasGoldStatus = true,
 72                 MemberSince = new DateTime(2012, 1, 1),
 73                 CreditRating = CustomerCreditRating.Good,
 74                 AverageRating = 42.42424242,
 75                 Street = "123 Somewhere Avenue",
 76                 City = "Nowhere",
 77                 Province = "Alberta",
 78                 Country = "Canada"
 79             };
 80             
 81             return customer;
 82         }
 83 
 84         private static IList<Customer> GetAll()
 85         {
 86             using (var session = SessionFactory.OpenSession())
 87             {
 88                 IList<Customer> list = session.CreateCriteria<Customer>().List<Customer>();
 89                 return list;
 90             }
 91         }
 92 
 93         private static Customer GetById(int id)
 94         {
 95             using (var session = SessionFactory.OpenSession())
 96             {
 97                 Customer customer = session.Get<Customer>(id);
 98                 return customer;
 99             }
100         }
101 
102         private static int Insert(Customer customer)
103         {
104             using (var session = SessionFactory.OpenSession())
105             {
106                 var identifier = session.Save(customer);
107                 session.Flush();
108                 return Convert.ToInt32(identifier);
109             }
110         }
111 
112         private static void Update(Customer customer)
113         {
114             using (var session = SessionFactory.OpenSession())
115             {
116                 session.SaveOrUpdate(customer);
117                 session.Flush();
118             }
119         }
120 
121         private static void Delete(int id)
122         {
123             using (var session = SessionFactory.OpenSession())
124             {
125                 var customer = session.Load<Customer>(id);
126                 session.Delete(customer);
127                 session.Flush();
128             }
129         }
130     }
131 }

7. 执行结果