相信大家应该都知道.NET Core现在不再支持原来的web.config配置文件了，取而代之的是json或xml配置文件。官方推荐的项目配置方式是使用appsettings.json配置文件，这对现有一些重度使用web.cofig配置的项目迁移可能是不可接受的。
但是好消息是，我们是可以直接在.NET Core 2.0项目种利用上现有的web.config的。本文将详细介绍.NET Core 2.0迁移之web.config 配置文件的相关内容，下面话不多说了，来一起看看详细的介绍吧。
迁移方法
1.首先在解决方案中引入System.Configuration.ConfigurationManager,只有引入它才可以让我们已有的读取web.config代码起作用.
2. 导入web.config文件到项目根目录，并将名称修改为app.config. 因为.NET Core的项目本质是控制台应用，所以ConfigurationManager的API会去默认读取app.config配置文件，而不是web.config配置文件。
3.去除config中和需要的配置无关的内容，主要是<system.web> , <system.webServer>和<system.codedom>等典型asp.net标签。
移除前：
<?xml version="1.0" encoding="utf-8"?> <configuration> <configSections> <!-- For more information on Entity Framework configuration, visit ?LinkID=237468 --> <section type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" /> </configSections> <connectionStrings> <add connectionString="Data Source=(LocalDb)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\aspnet-WebApplication24-20170824065102.mdf;Initial Catalog=aspnet-WebApplication24-20170824065102;Integrated Security=True" providerName="System.Data.SqlClient" /> </connectionStrings> <appSettings> <add key="webpages:Version" value="3.0.0.0" /> <add key="webpages:Enabled" value="false" /> <add key="ClientValidationEnabled" value="true" /> <add key="UnobtrusiveJavaScriptEnabled" value="true" /> <add key="MyKey" value="true"/> </appSettings> <system.web> <compilation debug="true" targetFramework="4.7" /> <httpRuntime targetFramework="4.7" /> <httpModules> <add type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web" /> </httpModules> </system.web> <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <dependentAssembly> <assemblyIdentity culture="neutral" publicKeyToken="30ad4fe6b2a6aeed" /> <bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" /> </dependentAssembly> <dependentAssembly> <assemblyIdentity publicKeyToken="31bf3856ad364e35" /> <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="1.1.0.0" /> </dependentAssembly> <dependentAssembly> <assemblyIdentity publicKeyToken="31bf3856ad364e35" /> <bindingRedirect oldVersion="0.0.0.0-1.5.2.14234" newVersion="1.5.2.14234" /> </dependentAssembly> <dependentAssembly> <assemblyIdentity publicKeyToken="31bf3856ad364e35" /> <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" /> </dependentAssembly> <dependentAssembly> <assemblyIdentity publicKeyToken="31bf3856ad364e35" /> <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" /> </dependentAssembly> <dependentAssembly> <assemblyIdentity publicKeyToken="31bf3856ad364e35" /> <bindingRedirect oldVersion="1.0.0.0-5.2.3.0" newVersion="5.2.3.0" /> </dependentAssembly> </assemblyBinding> </runtime> <system.webServer> <validation validateIntegratedModeConfiguration="false" /> <modules> <remove /> <add type="Microsoft.ApplicationInsights.Web.ApplicationInsightsHttpModule, Microsoft.AI.Web" preCondition="managedHandler" /> </modules> </system.webServer> <system.codedom> <compilers> <compiler language="c#;cs;csharp" extension=".cs" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:default /nowarn:1659;1699;1701" /> <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:default /nowarn:41008 /define:_MYTYPE=\"Web\" /optionInfer+" /> </compilers> </system.codedom> </configuration>
修改后：