依赖注入容器Unity介绍 dodo

Unity是微软团队开发的一个轻量级，可扩展的依赖注入容器，为松散耦合应用程序提供了很好的解决方案，支持构造器注入，属性注入，方法注入。

interface IDal  
    {  
        void save();  
    }  
    class SqlServerDal : IDal  
    {  
        public void save()  
        {  
            Console.WriteLine("SqlServer save.");  
        }  
    }  
    class OracleDal : IDal  
    {  
        public void save()  
        {  
            Console.WriteLine("Oracle save.");  
        }  
    }

Unity的实现如下：

IUnityContainer container = new UnityContainer();  
container.RegisterType<IDal, OracleDal>(); 
var dal = container.Resolve<IDal>();//这是得到OracleDal的实例。  
dal.save();

1、创建容器

IUnityContainer container = new UnityContainer();

2、注册映射

a) 代码方式注册映射：

container.RegisterType<IDal, OracleDal>();

RegisterType有以下几个重载方法：
RegisterType<TFrom, TTo>( )
RegisterType<TFrom, TTo>(LifetimeManager lifetime)
RegisterType<TFrom, TTo>(String name)
RegisterType<TFrom, TTo>(String name, LifetimeManager lifetime)
RegisterType<T>(LifetimeManager lifetime)
RegisterType<T>(String name, LifetimeManager lifetime)
RegisterType(Type from, Type to)
RegisterType(Type from, Type to, String name)
RegisterType(Type from, Type to, LifetimeManager lifetime)
RegisterType(Type from, Type to, String name, LifetimeManager lifetime)
RegisterType(Type t, LifetimeManager lifetime)
RegisterType(Type t, String name, LifetimeManager lifetime)

b) 通过配置方式注册映射：

UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity");

config文件配置如下：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <configSections>
      <section name="unity" 
         type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection, 
               Microsoft.Practices.Unity.Configuration" />
    </configSections>
    <unity>
      <containers>
        <container>
          <types>
            <type 
               type="UnityDemo.IDal,UnityDemo" 
               mapTo="UnityDemo.OracleDal,UnityDemo" />
          </types>
        </container>
      </containers>
    </unity>
</configuration>

配置方式完整代码：

IUnityContainer container = new UnityContainer();
UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity");
section.Configure(container);
var dal = container.Resolve<IDal>();//这是得到OracleDal的实例。  
dal.save();

3、获取对象实例

var dal = container.Resolve<IDal>();//这是得到OracleDal的实例。

可以通过方法ResolveAll来得到所有注册对象的实例：

<types>
            <type 
               type="UnityDemo.IDal,UnityDemo" name="oracle"
               mapTo="UnityDemo.OracleDal,UnityDemo" />
            <type 
               type="UnityDemo.IDal,UnityDemo" name="sqlserver"
               mapTo="UnityDemo.SqlServerDal,UnityDemo" />
</types>

var dals = container.ResolveAll<IDal>();
foreach(IDal dal in dals)
{
     dal.save();
}

结果：

参考文档：

http://unity.codeplex.com