Implementation of IOC by MEF (dependency inversion)

 

Scenario: Implement Dependency inversion. Managed extensibility framework (MEF) is a scalable management framework.

Preparation: defined interface, interface implementation class, introduction of namespace, system. componentmodel. Composition

[Implementation in the console]

 
---------------------------------------------------------NamespaceLeleapplicationdemo. icontract {Public InterfaceIexpor {StringGettxt (StringName,StringPassword );}}
 

 
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  using  leleapplicationdemo. icontract;  using  system. componentmodel. composition;  namespace  leleapplicationdemo. impl {[Export ( "ex1" ,  typeof  (iexpor)]  Public   class  demo1: iexpor { Public   string  gettxt ( string  name,  string  password) { return   string . format ( "{0} --- {1}" , name, password) ;}}----------------------------------------------------------- 

  using  leleapplicationdemo. icontract;  using  system. componentmodel. composition;  namespace  leleapplicationdemo. impl2 {[Export ( "ex2" ,  typeof  (iexpor)]  Public   class  demo1: iexpor { Public   string  gettxt ( string  name,  string  password) { return   string . format ( "***** {0} ^ {1}" , name, password) ;}}

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Class used for the interface:

  using  system. componentmodel. composition;  using  leleapplicationdemo. icontract;  namespace  consoleapplication. demo {[Export]  class  demoexpor {[import ( "ex1" )]  Public  iexpor expor {Get; set ;} [import ( "ex2" )]  Public  iexpor expor2 {Get; set ;}}

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Call:

  static   void  main ( string  [] ARGs) {aggregatecatalog catalog =  New  aggregatecatalog (); catalog. catalogs. add ( New  directorycatalog (directory. getcurrentdirectory (); catalog. catalogs. add ( New  assemblycatalog (assembly. getexecutingassembly (); compositioncontainer Tainer =  New  compositioncontainer (catiner); demoexpor dd = Tainer. getexportedvalue 
  
    (); console. writeline (DD. expor. gettxt (
    "N @ me" , 
    "P @ $ w0rd" ); console. writeline (DD. expor2.gettxt (
    "N @ me" , 
    "P @ $ w0rd" ); console. read () ;}
  

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Result:
 

 
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In mvc4, MEF implements Dependency inversion:
 

 
Preparation: interface, implementation class, introduction of namespace, system. componentmodel. Composition
 

 namespaces  namespace  mefiocdemo { Public   interface  iaccountsitecontract { string  test ( string  name,  string  password) ;}

UsingSystem. componentmodel. composition;UsingSystem. componentmodel. Composition. primitives ;---------------------------------------------------------------NamespaceMefiocdemo. impl {[Export (Typeof(Iaccountsitecontract)]Public ClassAccountcontract: iaccountsitecontract {Public StringTest (StringName,StringPassword ){Return String. Format ("Name: {0} password: {1 }", Name, password );}}}
 

 
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 // Create a MEF implementation class that implements the idependencyresolver Interface // Web applicationProgramStateless, that is, each access is performed independently, so the object instance generated by the IOC component must also be unique.  // Otherwise, operations by different users may be connected in a string, causing mutual interference.  // Use the httpcontext. Current. items set to save the compositioncontainer instance of the combined container, so that each user's data remains independent and the same object instance is used in the same HTTP request of the same user.  // In addition, you may need to manually obtain the instances in the combined container and cache the combined container to the application in the current context.  // (Refer to http://www.cnblogs.com/guomingfeng/archive/2013/05/21/mvc-ioc-mef.html MVC practical Architecture Design (2) -- use MEF practical IOC (dependency inversion ))  Using System; Using System. Collections. Generic; Using System. componentmodel. composition; Using System. componentmodel. Composition. Hosting; Using System. componentmodel. Composition. primitives; Using System. Web. MVC; Using System. Web; Namespace Mefiocdemo. IOC { Public   Class Iocdemo: idependencyresolver { Private Composablepartcatalog _ Catalog; Private   Const   String Iocdemokey = "Iocdemokey" ; Public Iocdemo (composablepartcatalog log) {_ catalog = log ;} Public Compositioncontainer container {get { If (! Httpcontext. Current. Items. Contains (iocdemokey) {httpcontext. Current. Items. Add (iocdemokey, New Compositioncontainer (_ Catalog);} compositioncontainer triner = (compositioncontainer) httpcontext. Current. items [iocdemokey]; httpcontext. Current. application [ "Container" ] = Triner; Return Triner ;}} Public   Object Getservice (type servicetype ){ String Contractname = attributedmodelservices. getcontractname (servicetype ); Return Container. getexportedvalueordefault < Object > (Contractname );} Public Ienumerable < Object > Getservices (type servicetype ){ Return Container. getexportedvalues < Object > (Servicetype. fullname );}}}

 
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Initialize in route Configuration
 

 Using Mefiocdemo. IOC; Using System. componentmodel. Composition. Hosting; Namespace Demomvc4 { // Note: For instructions on enabling the IIS6 or iis7 Classic mode,      // Please visit http://go.microsoft.com /? Linkid = 9394801      Public   Class Mvcapplication: system. Web. httpapplication { Protected   Void Application_start () {arearegistration. registerallareas (); webapiconfig. register (globalconfiguration. configuration); filterconfig. registerglobalfilters (globalfilters. filters); routeconfig. registerroutes (routetable. routes); bundleconfig. registerbundles (bundletable. bundles); directorycatalog catalog = New Directorycatalog (appdomain. currentdomain. setupinformation. privatebinpath); iocdemo demod = New Iocdemo (Catalog); dependencyresolver. setresolver (demod );}}}

 
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Usage:
 

  using  system. componentmodel. composition;  namespace  demomvc4.controllers {[Export]  Public   class  homecontroller: controller {[import]  private  mefiocdemo. iaccountsitecontract accountcontract;  Public  actionresult index () {viewbag. title = accountcontract. test ( "ABC" ,  "P @ ssw0rd"  );  return  View () ;}}

On the page:

 
@ {Viewbag. Title = viewbag. Title;} <H2 >@viewbag. Title </H2>
 

 

Result: