卸载程序集

2015-04-16

 

Assembly没有Unload方法，那么程序如何在运行状态下卸载程序集呢？

可以用AppDomain.Unload方法。

想法一 （失败）：

1. create new Domain
2. load assembly in new domain
3. unload the new Domain

代码如下：

1 using System; 2  3 using System.Reflection; 4  5 namespace UnloadAssembly 6 { 7     class Program 8     { 9         static void Main(string[] args)10         {11             string file1 = @"C:\code\UnloadAssembly\Assembly1\bin\Debug\Assembly1.dll";12             AppDomain appD = AppDomain.CreateDomain("#D1"); 13             AssemblyName myAssemblyName1 = AssemblyName.GetAssemblyName(file1);14             System.IO.File.Copy(file1, GetDestinateFile(file1), true);15             appD.Load(myAssemblyName1);16             string dName = appD.FriendlyName;17             AppDomain.Unload(appD);18         }19 20         public static string GetDestinateFile(string file)21         {22             return Environment.CurrentDirectory + @"\" + new System.IO.FileInfo(file).Name;23         }24     }25 }

图1 想法一

想法二 ^[1]（成功）：

Create a class say class "B" derived by MarshalByRefObject

• Write a method LoadAssembly({AssemblyPath}) in class "B". This function will only load that assembly and return void.
• Write another method ExecuteMethod({ClassName, MethodName, Params}) in class "B" . This function execute the method (name passed in the parameter) of the loaded assembly.

Create a new class say class "A". This will be our main class from where we will start and execute the code.

• write a main method in class "A" which will load class "B" in the new appdomain, and then call class B methods to load the assembly by passing the loadassembly method by passing assembly path and then by calling ExecuteMethod by passing method name and parameters.

 代码如下：

1 using System; 2 using System.Reflection; 3  4 namespace UnloadAssembly 5 { 6     class Program 7     { 8         static void Main(string[] args) 9         {10             string file1 = @"C:\code\UnloadAssembly\Assembly1\bin\Debug\Assembly1.dll";11             //Creating a new appdomain 12             AppDomainSetup setup = AppDomain.CurrentDomain.SetupInformation;13             //Create an instance of loader class in new appdomain 14             AppDomain newDomain = AppDomain.CreateDomain("newDomain", AppDomain.CurrentDomain.Evidence, setup);15 16             System.Runtime.Remoting.ObjectHandle obj = newDomain.CreateInstance(typeof(LoadMyAssembly).Assembly.FullName, typeof(LoadMyAssembly).FullName);17 18             //As the object we are creating is from another appdomain hence we will get that object in wrapped format and hence in next step we have unwrappped it 19             LoadMyAssembly loader = (LoadMyAssembly)obj.Unwrap();20 21             //Call loadassembly method so that the assembly will be loaded into the new appdomain amd the object will also remain in new appdomain only. 22             loader.LoadAssembly(file1);23 24             //Call exceuteMethod and pass the name of the method from assembly and the parameters. 25             loader.ExecuteStaticMethod("MyClass", "MyMethod", new object[] { 1 });26 27             //After the method has been executed call unload method of the appdomain. 28             AppDomain.Unload(newDomain); 29         }30 31         public sealed class LoadMyAssembly : MarshalByRefObject32         {33             private Assembly _assembly;34             System.Type MyType = null;35             object inst = null;36             public override object InitializeLifetimeService()37             {38                 return null;39             }40 41             public void LoadAssembly(string path)42             {43                 _assembly = Assembly.Load(AssemblyName.GetAssemblyName(path));44             }45 46             public object ExecuteStaticMethod(string className, string methodName, params object[] parameters)47             {48                 foreach (System.Type type in _assembly.GetTypes())49                 {50                     if (String.Compare(type.Name, className, true) == 0)51                     {52                         MyType = type;53                         inst = _assembly.CreateInstance(type.FullName);54 55                         break;56                     }57                 }58                 MethodInfo MyMethod = MyType.GetMethod(methodName, new Type[] { typeof(int) });59                 MyMethod.Invoke(inst, BindingFlags.InvokeMethod, null, parameters, null);60                 return null;61             }62         }63 64         public static string GetDestinateFile(string file)65         {66             return Environment.CurrentDirectory + @"\" + new System.IO.FileInfo(file).Name;67         }68     }69 }

被加载的assembly代码如下：

1     public class MyClass2     {3         public string MyMethod(int i)4         {5             return (i * 2).ToString();6         }7     }

参考

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