.NET Framework项目如何加载根目录的子目录下的dll文件

Specifies application base subdirectories for the common language runtime to search when loading assemblies.

<configuration>
<runtime>
<assemblyBinding>
<probing>

AttributeDescriptionprivatePathRequired attribute.
Specifies subdirectories of the application’s base directory that might contain assemblies. Delimit each subdirectory with a semicolon.
其中描述翻译为：指定应用程序的根目录的子目录,可能包含程序集。划用分号隔开每个子目录。

Example
The following example shows how to specify application base subdirectories the runtime should search for assemblies.

<configuration>
   <runtime>
      <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
         <probing privatePath="bin;bin2\subbin;bin3"/>
      </assemblyBinding>
   </runtime>
</configuration>

参考：https://msdn.microsoft.com/en-us/library/823z9h8w(v=vs.110).aspx