确保已安装Microsoft Web Development Tools，您可以在Visual Studio安装程序的Windows and Web Development

Ensure you have the Microsoft Web Development Tools installed which you can find in the Visual Studio installer under Windows and Web Development

安装后，启动Visual Studio并再次检查模板，您应该会看到ASP.NET Core模板.

Once installed, start up Visual Studio and check your templates again and you should see the ASP.NET Core templates.

更新

根据以下评论，

对于已经安装了Visual Studio 2015+但在初始安装过程中未添加功能的用户，您必须下载主Visual Studio安装程序并修改其功能

For those who already had visual studio 2015+ installed but didn't add the feature during the inital installation, you have to download the main visual studio installer and modify its features