WebApi多數據庫切換

用抽象工廠來解決多數據庫之間的切換問題是廣泛的，像如下幾篇文章都講的很具體

申明以前寫的存在強大漏洞 -- 以前有涉及到IoC Autofac的知識點,鄙人孤陋寡聞,在親身實踐後才發現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://www.cnblogs.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://www.cnblogs.com/tiger8000/archive/2012/01/04/2312134.html

可是考慮到在服務器上資源釋放的問題，仍是會選擇採用另外一種實現方式

先新建一個類庫 Interface，這個類庫對誰都不依賴，這裏有各類抽象的方法，但並無關於數據庫鏈接啊或者操做之類的抽象方法，這裏定義的抽象方法和controller裏的對應，

   1:  namespace WebApi.Interface

   2:  {

   3:      public interface ICommon

   4:      {

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

   6:      }

   7:  }

再定義一個具體的實現的類庫

   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:  }

  最後在Controller裏實現一個或多個接口就能夠了

   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爲空");

  13:              }

  14:              if (String.IsNullOrWhiteSpace(LoginName))

  15:              {

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

  17:              }

  18:   

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

  20:              return result;

  21:          }

針對不一樣的數據庫寫不一樣的實現的類庫,就能作到多數據庫的切換了,還的記得子啊webconfig中申明是對哪一個實現的實現

<add key="LoadAssembly" value="WebApi.OracleImp"/>，這樣切換不一樣的實現時就能夠實現對裏面不一樣實現方法的實現。

這裏要實現各依賴項的加載還必需要作到一下幾步：

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);

至於爲何須要好好研究會