用抽象工廠來解決多數(shù)據(jù)庫之間的切換問題是普遍的，像以下幾篇文章都講的很具體

申明之前寫的存在強(qiáng)大漏洞 -- 之前有涉及到IoC Autofac的知識(shí)點(diǎn),鄙人孤陋寡聞,在親身實(shí)踐后才發(fā)現(xiàn)其中奧妙可參照一下幾篇文章

http://www.codePRoject.com/Articles/808894/IoC-in-asp.net-MVC-using-Autofac

http://code.google.com/p/autofac/wiki/Mvc3Integration 

http://m.survivalescaperooms.com/zhouruifu/archive/2012/04/03/dependency-injection-in-asp-net-web-api-using-autofac.html

http://blog.csdn.net/zouyujie1127/article/details/15341569

http://m.survivalescaperooms.com/tiger8000/archive/2012/01/04/2312134.html

但是考慮到在服務(wù)器上資源釋放的問題，還是會(huì)選擇采用另一種實(shí)現(xiàn)方式

先新建一個(gè)類庫 Interface，這個(gè)類庫對(duì)誰都不依賴，這里有各種抽象的方法，但并沒有關(guān)于數(shù)據(jù)庫連接啊或者操作之類的抽象方法，這里定義的抽象方法和controller里的對(duì)應(yīng)，

   1:  namespace WebApi.Interface

   2:  {

   3:      public interface ICommon

   4:      {

   5:          int regist(String LoginName, String PassWord);

   6:      }

   7:  }

再定義一個(gè)具體的實(shí)現(xiàn)的類庫

   1:  namespace WebApi.OracleImp

   2:  {

   3:      public class Common: WebApi.Interface.ICommon

   4:      {

   5:          public int regist(String LoginName, String Password)

   6:          {

   7:              using (var conn = new System.Data.OracleClient.OracleConnection(OracleHelper.ConnString))

   8:              {

   9:                  conn.Open();

  10:                  using (var command = conn.CreateCommand())

  11:                  {

  12:                      command.Parameters.Clear();

  13:                      command.Parameters.Add(new System.Data.OracleClient.OracleParameter(":LoginName", LoginName));

  14:                      command.Parameters.Add(new System.Data.OracleClient.OracleParameter(":Password", Password));

  15:                      command.CommandText = "insert into  YG(DLM,MM) value(:LoginName,:Password)";

  16:                    var result = command.ExecuteNonQuery;

  17:                   return result;

  18:                  }

  19:               }

  20:          }

  21:      }

  22:  }

  最后在Controller里實(shí)現(xiàn)一個(gè)或多個(gè)接口就可以了

   1:          Interface.ICommon _common;

   2:          public DemoController(Interface.ICommon common)

   3:          {

   4:              this._common = common;

   5:          }

   6:          [HttpPost]

   7:          public int regist(String LoginName, String Password)

   8:          {

   9:   

  10:              if (String.IsNullOrWhiteSpace(Password))

  11:              {

  12:                 throw new exception("password為空");

  13:              }

  14:              if (String.IsNullOrWhiteSpace(LoginName))

  15:              {

  16:                 throw new exception("(LoginName))為空");

  17:              }

  18:   

  19:              var result = _common.regist(LoginName, Password);

  20:              return result;

  21:          }

針對(duì)不同的數(shù)據(jù)庫寫不同的實(shí)現(xiàn)的類庫,就能做到多數(shù)據(jù)庫的切換了,還的記得子啊webconfig中申明是對(duì)哪個(gè)實(shí)現(xiàn)的實(shí)現(xiàn)

<add key="LoadAssembly" value="WebApi.OracleImp"/>，這樣切換不同的實(shí)現(xiàn)時(shí)就可以實(shí)現(xiàn)對(duì)里面不同實(shí)現(xiàn)方法的實(shí)現(xiàn)。

這里要實(shí)現(xiàn)各依賴項(xiàng)的加載還必須要做到一下幾步：

1.先添加引用

using Autofac;
using Autofac.Integration.WebApi;

2.

var builder = new ContainerBuilder();
builder.RegisterAssemblyTypes(Assembly.Load(ConfigurationSettings.AppSettings["LoadAssembly"]))
.Where(t => true)
.AsImplementedInterfaces();
builder.RegisterApiControllers(Assembly.GetExecutingAssembly());
var container = builder.Build();
GlobalConfiguration.Configuration.DependencyResolver = new AutofacWebApiDependencyResolver(container);

至于為什么需要好好研究會(huì)