在本章中，我们将介绍如何覆盖NHibernate配置.您需要记住几件事.
首先，NHibernate中的配置是附加的.
因此，您不必只使用单个xml文件，或者您不必使用基于代码的配置或流畅的NHibernate.
您可以混合搭配所有这些方法，具体取决于您要如何配置应用程序.
要记住的重要一点是，最后配置获胜.
在以下示例中，您可以看到我们创建了配置对象，使用基于代码的配置对其进行配置，最后调用 cfg.configure()方法，该方法加载hibernate.cfg.xml文件.
String Data Source = asia13797\\sqlexpress;
String Initial Catalog = NHibernateDemoDB;
String Integrated Security = True;
String Connect Timeout = 15;
String Encrypt = False;
String TrustServerCertificate = False;
String ApplicationIntent = ReadWrite;
String MultiSubnetFailover = False;
cfg.DataBaseIntegration(x = > { x.ConnectionString = "Data Source +
Initial Catalog + Integrated Security + Connect Timeout + Encrypt +
TrustServerCertificate + ApplicationIntent + MultiSubnetFailover";
x.Driver<SqlClientDriver>();
x.Dialect<MsSql2008Dialect>();
x.LogSqlInConsole = true;
});
cfg.Configure();因此，hibernate.cfg.xml中的任何内容都会覆盖代码设置的设置 - 基于配置.
通过反转这两个进程，我们可以在hibernate.cfg.xml中使用默认值，然后在基于代码的配置中执行覆盖.
如果您使用基于代码的配置，并且没有任何东西阻止您使用hibernate.cfg.xml文件，则没有任何内容排除.
让我们看一个简单的例子，我们将使用基于xml和基于代码的混合覆盖配置配置.
我们还使用以下代码将连接字符串移动到 app.config 文件.
<?xml version = "1.0" encoding = "utf-8" ?> <configuration> <startup> <supportedRuntime version = "v4.0" sku = ".NETFramework,Version = v4.5" /> </startup> <connectionStrings> <add name = "default" connectionString = "Data Source = asia13797\\sqlexpress; Initial Catalog = NHibernateDemoDB; Integrated Security = True; Connect Timeout = 15; Encrypt = False; TrustServerCertificate = False; ApplicationIntent = ReadWrite; MultiSubnetFailover = False"/> </connectionStrings> </configuration>
连接字符串位于某个带有默认名称的 app.config 文件中.现在，我们需要在hibernate.cfg.xml文件中提及默认名称而不是连接字符串.
<?xml version = "1.0" encoding = "utf-8" ?> <hibernate-configuration xmlns = "urn:nhibernate-configuration-2.2"> <session-factory> <property name = "connection.connection_string">default</property> <property name = "connection.driver_class"> NHibernate.Driver.SqlClientDriver </property> <property name = "dialect"> NHibernate.Dialect.MsSql2008Dialect </property> <mapping assembly = "NHibernateDemoApp"/> </session-factory> </hibernate-configuration>
让我们从基于代码的配置中评论连接字符串部分，驱动程序和方言部分，因为程序将从hibernate.cfg中读取它. xml文件和 LogSqlInConsole 部分将保留在基于代码的配置中.
using HibernatingRhinos.Profiler.Appender.NHibernate;
using NHibernate.Cfg;
using NHibernate.Dialect;
using NHibernate.Driver;
using System;
using System.Linq;
using System.Reflection;
namespace NHibernateDemoApp {
class Program {
static void Main(string[] args) {
NHibernateProfiler.Initialize();
var cfg = new Configuration();
String Data Source = asia13797\\sqlexpress;
String Initial Catalog = NHibernateDemoDB;
String Integrated Security = True;
String Connect Timeout = 15;
String Encrypt = False;
String TrustServerCertificate = False;
String ApplicationIntent = ReadWrite;
String MultiSubnetFailover = False;
cfg.DataBaseIntegration(x = > { //x.ConnectionString = "Data Source +
Initial Catalog + Integrated Security + Connect Timeout + Encrypt +
TrustServerCertificate + ApplicationIntent + MultiSubnetFailover";
//x.Driver<SqlClientDriver>();
//x.Dialect<MsSql2008Dialect>();
x.LogSqlInConsole = true;
});
cfg.Configure();
cfg.AddAssembly(Assembly.GetExecutingAssembly());
var sefact = cfg.BuildSessionFactory();
using (var session = sefact.OpenSession()) {
using (var tx = session.BeginTransaction()) {
var students = session.CreateCriteria<Student>().List<Student>();
Console.WriteLine("\nFetch the complete list again\n");
foreach (var student in students) {
Console.WriteLine("{0} \t{1} \t{2} \t{3}", student.ID,
student.FirstName, student.LastName, student.AcademicStanding);
}
tx.Commit();
}
Console.ReadLine();
}
}
}
}现在，当你运行应用程序时，你会看到程序已从基于代码的配置和hibernate.cfg.xml文件中的其他配置读取日志.
NHibernate: SELECT this_.ID as ID0_0_, this_.LastName as LastName0_0_, this_.FirstMidName as FirstMid3_0_0_, this_.AcademicStanding as Academic4_0_0_ FROM Student this_ Fetch the complete list again 1 Allan Bommer Excellent 2 Jerry Lewis Good
所以现在我们的 hibernate.cfg.xml 文件，其中一些是在基于代码的配置中，并且根据调用基于代码的顺序与 configure()，我们可以更改其中哪一个覆盖另一个.
