在C#中使用AppDomain动态加载和卸载dll

public static void Main()


    {
        // Use the file name to load the assembly into the current
        // application domain.
        Assembly a = Assembly.Load("example");
        // Get the type to use.
        Type myType = a.GetType("Example");
        // Get the method to call.
        MethodInfo myMethod = myType.GetMethod("MethodA");
        // Create an instance.
        object obj = Activator.CreateInstance(myType);
        // Execute the method.
        myMethod.Invoke(obj,null);
    }

至于如何卸载它,你必须卸载AppDomain本身,见this

AppDomain Temporary = AppDomain.CreateDomain("Temporary");
try
{
  Gateway Proxy = 
    (Gateway) Temporary.CreateInstanceAndUnwrap("Shim","Shim.Gateway");

  Match M = Proxy.LoadAndMatch("Plugin.dll","Though the tough cough and hiccough,plough them through");  
}
finally
{
  AppDomain.Unload(Temporary);
}