使用Microsoft.Practices.Unity 依赖注入

    Unity是微软Patterns & Practices团队所开发的一个轻量级的，并且可扩展的依赖注入(Dependency Injection)容器，它支持常用的三种依赖注入方式：构造器注入(Constructor Injection)、属性注入(Property Injection)，以及方法调用注入(Method Call Injection).

    假设我们有下面的场景代码，在代码里面有一个很简单的customer对象，customer 对象有个save 方法， 这个方法通过调用ICustomerDataAccess.Save将数据持久到数据库中, 在列子中我们实现了dataaccess的sql版本和mysql版本，也就是说我们这个customer对象，可以支持持久化到sql server 或 mysql.

       

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;using Microsoft.Practices.Unity;namespace UnitySample{    public interface ICustomerDataAccess    {        void Save(Customer c);    }    public class CustomerSqlDataAccess : ICustomerDataAccess    {        public void Save(Customer c)        {            Console.Write("{2}, save data id:{0},name{1}",c.Id,c.Name,this.GetType().ToString());        }    }    public class CustomerMysqlDataAccess : ICustomerDataAccess    {        public void Save(Customer c)        {            Console.Write("{2}, save data id:{0},name{1}", c.Id, c.Name, this.GetType().ToString());        }    }    public class Customer    {        public ICustomerDataAccess CustomerDataAccess { get; set; }        public string Id { get; set; }        public string Name { get; set; }        public void Save()        {            CustomerDataAccess.Save(this);        }    }    class Program    {        static void Main(string[] args)        {        }    }}

 

传统做法可能是在配置文件中填几个一个变量 dbType = sql  or my sql. 然后在customer 对象中根据设定的db type 来实力化不同的dataaccess.

   代码可能会是下面这个样子，这样的话，customer 对象实际上依赖于CustomerSqlDataAccess 和 CustomerSqlDataAccess 的，而且，未来比如要新增加其他数据库的支持，则必须修改customer 对象的源代码。

 

 public Customer() {            if (DbType = "sql")            {                CustomerDataAccess = new CustomerSqlDataAccess();            }            else            {                CustomerDataAccess = new CustomerSqlDataAccess();            } }

下面我们使用unity 来解除customer 对象对  CustomerSqlDataAccess 和 CustomerSqlDataAccess 的依赖。

一、 属性注入(Property Injection)

    1.  配置unity

　　   为了以后调用方便，我这里建立了一个静态方法，然后注入了两个dataaccess。

 public class UnitySetup    {        public static void Config()        {            var container = new UnityContainer();            container.RegisterType<ICustomerDataAccess, CustomerSqlDataAccess>();            container.RegisterType<ICustomerDataAccess, CustomerSqlDataAccess>("mysql");        }    }

　　然后我们需要在Main函数中调用这个方法配置unity containter.

　　

　　　　　static void Main(string[] args)        {            UnitySetup.Config();        }

 

    2. 标记属性注入

　　 这步很简单，直接在customer 类中的ICustomerDataAccess 定义上面添加[Dependency]标注即可。

      

[Dependency]public ICustomerDataAccess CustomerDataAccess { get; set; }

 

    3. 通过resove 获取对象

 

            var container = new UnityContainer();            UnitySetup.Config(container);            var sqlCustomer = container.Resolve<ICustomerDataAccess>();            var mysqlCustomer = container.Resolve<ICustomerDataAccess>("mysql");

上面的代码就分别获取了CustomerSqlDataAccess 实例和CustomerSqlDataAccess实例

二 、构造器注入(Constructor Injection)

  1.  配置unity

　　  

  unityContainer.RegisterType<Customer>(                new InjectionConstructor(new ResolvedParameter<ICustomerDataAccess>()));            unityContainer.RegisterType<Customer>("mysqlCustomer",                new InjectionConstructor(new ResolvedParameter<ICustomerDataAccess>("mysql")));

添加两行注册customer 对想到container.

 

2. 获取

 var sqlCustomer = container.Resolve<Customer>(); var myqlCustomer = container.Resolve<Customer>("mysqlCustomer");

完整代码如下

using System;using System.Collections.Generic;using System.Data;using System.Linq;using System.Text;using System.Threading.Tasks;using Microsoft.Practices.Unity;namespace UnitySample{        public interface ICustomerDataAccess    {        void Save(Customer c);    }    public class CustomerSqlDataAccess : ICustomerDataAccess    {        public void Save(Customer c)        {            Console.WriteLine("{2}, save data id:{0},name{1}",c.Id,c.Name,this.GetType().ToString());        }    }    public class CustomerMysqlDataAccess : ICustomerDataAccess    {        public void Save(Customer c)        {            Console.WriteLine("{2}, save data id:{0},name{1}", c.Id, c.Name, this.GetType().ToString());        }    }    public class UnitySetup    {        public static void Config(IUnityContainer unityContainer)        {            unityContainer.RegisterType<ICustomerDataAccess, CustomerSqlDataAccess>();            unityContainer.RegisterType<ICustomerDataAccess, CustomerMysqlDataAccess>("mysql");            unityContainer.RegisterType<Customer>(                new InjectionConstructor(new ResolvedParameter<ICustomerDataAccess>()));            unityContainer.RegisterType<Customer>("mysqlCustomer",                new InjectionConstructor(new ResolvedParameter<ICustomerDataAccess>("mysql")));        }    }    public class Customer    {        private ICustomerDataAccess CustomerDataAccess { get; set;}        public string Id { get; set; }        public string Name { get; set; }        public Customer(ICustomerDataAccess customerDataAccess)        {            CustomerDataAccess = customerDataAccess;        }        public void Save()        {            CustomerDataAccess.Save(this);        }    }    class Program    {        static void Main(string[] args)        {            var container = new UnityContainer();            UnitySetup.Config(container);            var sqlCustomer = container.Resolve<Customer>();            var myqlCustomer = container.Resolve<Customer>("mysqlCustomer");            sqlCustomer.Save();            myqlCustomer.Save();                        Console.ReadKey();        }    }}

三 、 方法调用注入(Method Call Injection)

 方法调用注入和输入注入有点类似，只需要在调用的方法上面添加[InjectionMethod] 标注即可

  1.  配置unity

　　  

 unityContainer.RegisterType<Customer>("mysqlCustomer",                new InjectionMethod("SetDataAccess", new ResolvedParameter<ICustomerDataAccess>("mysql")));

 

2. 获取

 var sqlCustomer = container.Resolve<Customer>(); var myqlCustomer = container.Resolve<Customer>("mysqlCustomer");

 完成后的代码如下

using System;using System.Collections.Generic;using System.Data;using System.Linq;using System.Text;using System.Threading.Tasks;using Microsoft.Practices.Unity;namespace UnitySample{        public interface ICustomerDataAccess    {        void Save(Customer c);    }    public class CustomerSqlDataAccess : ICustomerDataAccess    {        public void Save(Customer c)        {            Console.WriteLine("{2}, save data id:{0},name{1}",c.Id,c.Name,this.GetType().ToString());        }    }    public class CustomerMysqlDataAccess : ICustomerDataAccess    {        public void Save(Customer c)        {            Console.WriteLine("{2}, save data id:{0},name{1}", c.Id, c.Name, this.GetType().ToString());        }    }    public class UnitySetup    {        public static void Config(IUnityContainer unityContainer)        {            unityContainer.RegisterType<ICustomerDataAccess, CustomerSqlDataAccess>();            unityContainer.RegisterType<ICustomerDataAccess, CustomerMysqlDataAccess>("mysql");                        unityContainer.RegisterType<Customer>("mysqlCustomer",                new InjectionMethod("SetDataAccess", new ResolvedParameter<ICustomerDataAccess>("mysql")));        }    }    public class Customer    {        private ICustomerDataAccess CustomerDataAccess { get; set;}        public string Id { get; set; }        public string Name { get; set; }              public void Save()        {            CustomerDataAccess.Save(this);        }        [InjectionMethod]        public void SetDataAccess(ICustomerDataAccess dataAccess)        {            CustomerDataAccess = dataAccess;        }    }    class Program    {        static void Main(string[] args)        {            var container = new UnityContainer();            UnitySetup.Config(container);            var sqlCustomer = container.Resolve<Customer>();            var mysqlCustomer = container.Resolve<Customer>("mysqlCustomer");            sqlCustomer.Save();            mysqlCustomer.Save();            Console.ReadKey();        }    }}

好了，通过使用unity 依赖注入，customer 对象不再依赖具体的CustomerSqlDataAccess 和 CustomerMysqlDataAccess., 只依赖于接口ICustomerDataAccess。

上面就是unity 的基本用法介绍。