.NET 引用两个不同版本的dll的几种方法

// 在文件顶部定义外部别名
extern alias Version1;
extern alias Version2;

using System;

class Program
{
    static void Main()
    {
        // 使用版本1
        Version1::MyNamespace.MyClass obj1 = new Version1::MyNamespace.MyClass();
        obj1.DoSomething();
        
        // 使用版本2
        Version2::MyNamespace.MyClass obj2 = new Version2::MyNamespace.MyClass();
        obj2.DoSomething();
        
        // 或者使用全局命名空间限定
        var obj3 = new global::MyNamespace.MyClass(); // 使用默认引用
    }
}

<configuration>
  <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="MyAssembly" 
                         publicKeyToken="32ab4ba45e0a69a1" 
                         culture="neutral" />
        <bindingRedirect oldVersion="1.0.0.0" newVersion="2.0.0.0"/>
        <codeBase version="1.0.0.0" href="lib\v1\MyAssembly.dll" rel="external nofollow" />
        <codeBase version="2.0.0.0" href="lib\v2\MyAssembly.dll" rel="external nofollow" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>
</configuration>

using System;
using System.Reflection;

class Program
{
    static void Main()
    {
        // 动态加载不同版本的程序集
        Assembly version1 = Assembly.LoadFrom(@"path\to\version1\MyAssembly.dll");
        Assembly version2 = Assembly.LoadFrom(@"path\to\version2\MyAssembly.dll");
        
        // 通过反射创建实例
        dynamic obj1 = version1.CreateInstance("MyNamespace.MyClass");
        dynamic obj2 = version2.CreateInstance("MyNamespace.MyClass");
        
        obj1.DoSomething();
        obj2.DoSomething();
    }
}

// Version1Wrapper.cs
public class Version1Wrapper
{
    private dynamic _instance;
    
    public Version1Wrapper(string dllPath)
    {
        var assembly = Assembly.LoadFrom(dllPath);
        _instance = assembly.CreateInstance("MyNamespace.MyClass");
    }
    
    public void DoSomething() => _instance.DoSomething();
}

// 使用包装器
var wrapperV1 = new Version1Wrapper(@"lib\v1\MyAssembly.dll");
var wrapperV2 = new Version1Wrapper(@"lib\v2\MyAssembly.dll");

using System;
using System.Reflection;

class Program
{
    static void Main()
    {
        AppDomain domain1 = AppDomain.CreateDomain("Version1Domain");
        AppDomain domain2 = AppDomain.CreateDomain("Version2Domain");
        
        // 在不同应用域中加载不同版本
        domain1.ExecuteAssembly(@"path\to\version1\app.exe");
        domain2.ExecuteAssembly(@"path\to\version2\app.exe");
        
        AppDomain.Unload(domain1);
        AppDomain.Unload(domain2);
    }
}