在一行中通过Namespace名称的一部分获取所有类:

var allClasses = Assembly.GetExecutingAssembly().GetTypes().Where(a => a.IsClass && a.Namespace != null && a.Namespace.Contains(@"..your namespace...")).ToList();

您将无法获得一个名称空间中的所有类型，因为一个名称空间可以桥接多个程序集，但是您可以获得一个程序集中的所有类并检查它们是否属于该名称空间。

assembly .GetTypes()在本地程序集上工作，或者您可以先加载一个程序集，然后在其上调用GetTypes()。

正如FlySwat所说，您可以在多个程序集中拥有相同的命名空间(例如System.Collections.Generic)。如果还没有加载所有这些程序集，则必须加载它们。完整的答案是:

AppDomain.CurrentDomain.GetAssemblies()
                       .SelectMany(t => t.GetTypes())
                       .Where(t => t.IsClass && t.Namespace == @namespace)

这应该工作，除非你想要其他域的类。要获得所有域名的列表，请点击此链接。

Namespaces are actually rather passive in the design of the runtime and serve primarily as organizational tools. The Full Name of a type in .NET consists of the Namespace and Class/Enum/Etc. combined. If you only wish to go through a specific assembly, you would simply loop through the types returned by assembly.GetExportedTypes() checking the value of type.Namespace. If you were trying to go through all assemblies loaded in the current AppDomain it would involve using AppDomain.CurrentDomain.GetAssemblies()

//a simple combined code snippet 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;

namespace MustHaveAttributes
{
  class Program
  {
    static void Main ( string[] args )
    {
      Console.WriteLine ( " START " );

      // what is in the assembly
      Assembly a = Assembly.Load ( "MustHaveAttributes" );
      Type[] types = a.GetTypes ();
      foreach (Type t in types)
      {

        Console.WriteLine ( "Type is {0}", t );
      }
      Console.WriteLine (
         "{0} types found", types.Length );

      #region Linq
      //#region Action


      //string @namespace = "MustHaveAttributes";

      //var q = from t in Assembly.GetExecutingAssembly ().GetTypes ()
      //        where t.IsClass && t.Namespace == @namespace
      //        select t;
      //q.ToList ().ForEach ( t => Console.WriteLine ( t.Name ) );


      //#endregion Action  
      #endregion

      Console.ReadLine ();
      Console.WriteLine ( " HIT A KEY TO EXIT " );
      Console.WriteLine ( " END " );
    }
  } //eof Program


  class ClassOne
  {

  } //eof class 

  class ClassTwo
  {

  } //eof class


  [System.AttributeUsage ( System.AttributeTargets.Class |
    System.AttributeTargets.Struct, AllowMultiple = true )]
  public class AttributeClass : System.Attribute
  {

    public string MustHaveDescription { get; set; }
    public string MusHaveVersion { get; set; }


    public AttributeClass ( string mustHaveDescription, string mustHaveVersion )
    {
      MustHaveDescription = mustHaveDescription;
      MusHaveVersion = mustHaveVersion;
    }

  } //eof class 

} //eof namespace 

在一行中通过Namespace名称的一部分获取所有类:

var allClasses = Assembly.GetExecutingAssembly().GetTypes().Where(a => a.IsClass && a.Namespace != null && a.Namespace.Contains(@"..your namespace...")).ToList();