我在 Winforms 工作，C# .NET4.5
我在程序集 A 中有一个名为 classA 的类，它提供了 method1
在我的主程序集中，我可以调用此方法，但在某些情况下，我 100% 确信这不会发生，因为注册表项中有一些内部标志：
if( valueFromRegistryIsAlwaysFalse)
{
var A = new classA();
A.method1();
}
当我在注册表中设置这个值时，我不想为程序集 A 提供主可执行文件，但是即使我不使用它需要程序集 A 启动的方法。我当然明白了，但是有没有办法解决这个问题？
通常，当 CLI 对使用尚未加载的程序集的类型的任何包含方法进行 JIT 处理时，程序集加载和融合会按需发生。所以：“解决”这个问题的方法是将所有涉及此程序集中类型的代码移动到永远不会执行的方法中。例如：
if( valueFromRegistryIsAlwaysFalse)
{
DoStuff();
}
[System.Runtime.CompilerServices.MethodImpl(
System.Runtime.CompilerServices.MethodImplOptions.NoInlining)]
void DoStuff()
{
var A = new classA();
A.method1();
}
有了这个改变，原来的方法没有提到classA，所以方法可以被JITted而不需要额外的汇编；并且因为DoStuff从未执行/ JITted，它也永远不会从那里加载。
创建调用者和 classA 都引用的接口程序集。删除引用并动态加载程序集并实例化类。
Assembly asm = Assembly.LoadFile(@"C:\classAAssembly.dll");
Type type = asm.GetType("classA");
IClassA a = Activator.CreateInstance(type) as IClassA;
通常，框架会按需加载程序集。另一种方法是使用动态负载模式或复合模式。从框架 4.0 开始，MS 引入了System.Addin命名空间来帮助程序员。我有以下类，我在我的项目中使用它来实现与 Framework 2.0 兼容性相同的目的：
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Reflection;
namespace MyNamespace
{
[Serializable]
public enum CompositeLoaderFilter
{
ImplementsInterface = 0,
InheritsBaseClass = 1
}
[Serializable]
public static class Composite
{
private static readonly CompositeManager manager = new CompositeManager();
public static CompositeManager Manager { get { return manager; } }
}
[Serializable]
public class CompositeManager : MarshalByRefObject
{
private SortedList<string, Type> m_addIns;
public int GetInMemoryComponents(Type addInType, CompositeLoaderFilter filter)
{
m_addIns = internal_GetInMemoryServices(addInType, filter);
return m_addIns.Count;
}
public int GetComponents(Type addInType, CompositeLoaderFilter filter)
{
string addInPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
return GetComponents(addInPath, "*.dll", SearchOption.TopDirectoryOnly, addInType, filter);
}
public int GetComponents(string addInSearchPattern, Type addInType, CompositeLoaderFilter filter)
{
string addInPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
return GetComponents(addInPath, addInSearchPattern, SearchOption.TopDirectoryOnly, addInType, filter);
}
public int GetComponents(string addInPath, string addInSearchPattern, Type addInType, CompositeLoaderFilter filter)
{
return GetComponents(addInPath, addInSearchPattern, SearchOption.TopDirectoryOnly, addInType, filter);
}
public int GetComponents(string addInPath, string addInSearchPattern, SearchOption addInSearchOption, Type addInType, CompositeLoaderFilter filter)
{
AppDomainSetup setup = AppDomain.CurrentDomain.SetupInformation;
setup.PrivateBinPath = addInPath;
setup.ShadowCopyFiles = "false";
AppDomain m_appDomain = AppDomain.CreateDomain("MyNamespace.CompositeManager", null, setup);
CompositeManager m_remoteLoader = (CompositeManager)m_appDomain.CreateInstanceFromAndUnwrap(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "MyAssembly.dll"), "MyNamespace.CompositeManager");
m_addIns = m_remoteLoader.RemoteGetServices(addInPath, addInSearchPattern, addInSearchOption, addInType, filter);
#if DEBUG
DebugLoadedAssemblies();
#endif
AppDomain.Unload(m_appDomain);
return m_addIns.Count;
}
public object CreateInstance(string typeName)
{
if (!m_addIns.ContainsKey(typeName))
throw new ArgumentException(string.Format(CultureInfo.CurrentCulture, "Type {0} was not loaded..", typeName), "typeName");
MethodInfo method = m_addIns[typeName].GetMethod("GetInstance", BindingFlags.Static | BindingFlags.Public | BindingFlags.Instance | BindingFlags.FlattenHierarchy);
if (method != null)
return method.Invoke(m_addIns[typeName], null);
else return Activator.CreateInstance(m_addIns[typeName]);
}
public object CreateInstance(Type type)
{
if (type == null)
throw new ArgumentNullException("type", "Type is null");
if (!m_addIns.ContainsKey(type.FullName))
throw new ArgumentException(string.Format(CultureInfo.CurrentCulture, "Type {0} was not loaded..", type.FullName), "type");
MethodInfo method = type.GetMethod("GetInstance", BindingFlags.Static | BindingFlags.Public | BindingFlags.Instance | BindingFlags.FlattenHierarchy);
if (method != null)
return method.Invoke(type, null);
else return Activator.CreateInstance(type);
}
public T CreateInstance<T>()
{
if (!m_addIns.ContainsKey(typeof(T).FullName))
throw new ArgumentException(string.Format(CultureInfo.CurrentCulture, "Type {0} was not loaded..", typeof(T).FullName), "T");
MethodInfo method = typeof(T).GetMethod("GetInstance", BindingFlags.Static | BindingFlags.Public | BindingFlags.Instance | BindingFlags.FlattenHierarchy);
if (method != null)
return (T)method.Invoke(typeof(T), null);
else return Activator.CreateInstance<T>();
}
public IEnumerable<Type> AvailableServices
{
get
{
foreach (KeyValuePair<string, Type> item in m_addIns)
{
yield return item.Value;
}
}
}
public Type[] AvailableTypes
{
get
{
List<Type> list = new List<Type>();
foreach (KeyValuePair<string, Type> item in m_addIns)
list.Add(item.Value);
return list.ToArray();
}
}
public T[] GetObjects<T>()
{
List<T> list = new List<T>();
foreach (KeyValuePair<string, Type> item in m_addIns)
list.Add((T)CreateInstance(item.Value));
return list.ToArray();
}
public object[] AvailableObjects
{
get
{
List<object> list = new List<object>();
foreach (KeyValuePair<string, Type> item in m_addIns)
list.Add(CreateInstance(item.Value));
return list.ToArray();
}
}
internal SortedList<string, Type> internal_GetInMemoryServices(Type addInType, CompositeLoaderFilter filter)
{
SortedList<string, Type> validAddIns = new SortedList<string, Type>();
Assembly[] assemblies = AppDomain.CurrentDomain.GetAssemblies();
foreach (Assembly assembly in assemblies)
{
try
{
Type[] types = assembly.GetTypes();
foreach (Type type in types)
{
switch (filter)
{
case CompositeLoaderFilter.ImplementsInterface:
if (type.GetInterface(addInType.Name) != null)
validAddIns.Add(type.FullName, type);
break;
case CompositeLoaderFilter.InheritsBaseClass:
if (type.BaseType == addInType)
validAddIns.Add(type.FullName, type);
break;
}
}
}
catch (FileLoadException flex)
{
Debug.WriteLine(string.Format(CultureInfo.CurrentCulture, "{0} MyNamespace.CompositeManager: {1}", DateTime.Now.ToString(), flex.Message));
}
catch (Exception ex)
{
Debug.WriteLine(string.Format(CultureInfo.CurrentCulture, "{0} MyNamespace.CompositeManager: {1}", DateTime.Now.ToString(), ex.Message));
}
}
return validAddIns;
}
internal SortedList<string, Type> RemoteGetServices(string addInPath, string addInSearchPattern, SearchOption addInSearchOption, Type addInType, CompositeLoaderFilter filter)
{
string[] files = Directory.GetFiles(addInPath, addInSearchPattern, addInSearchOption);
SortedList<string, Type> validAddIns = new SortedList<string, Type>();
if (files.Length > 0)
{
foreach (string file in files)
{
if (String.CompareOrdinal(addInPath, file) != 0)
{
try
{
Assembly assembly = Assembly.LoadFrom(file);
Type[] types = assembly.GetTypes();
foreach (Type type in types)
{
switch (filter)
{
case CompositeLoaderFilter.ImplementsInterface:
if (type.GetInterface(addInType.Name) != null)
validAddIns.Add(type.FullName, type);
break;
case CompositeLoaderFilter.InheritsBaseClass:
if (type.BaseType == addInType)
validAddIns.Add(type.FullName, type);
break;
}
}
}
catch (FileLoadException flex)
{
Debug.WriteLine(string.Format(CultureInfo.CurrentCulture, "{0} MyNamespace.CompositeManager: {1}", DateTime.Now.ToString(), flex.Message));
}
catch (Exception ex)
{
Debug.WriteLine(string.Format(CultureInfo.CurrentCulture, "{0} MyNamespace.CompositeManager: {1}", DateTime.Now.ToString(), ex.Message));
}
}
}
}
#if DEBUG
DebugLoadedAssemblies();
#endif
return validAddIns;
}
#if DEBUG
internal void DebugLoadedAssemblies()
{
foreach (Assembly a in AppDomain.CurrentDomain.GetAssemblies())
{
//Debug.WriteLine(string.Format("Domain: {0} Assembly: {1}", AppDomain.CurrentDomain.FriendlyName, a.FullName));
}
}
#endif
}
}
以下示例用法：
Composite.Manager.GetComponents(typeof(IMyService), CompositeLoaderFilter.ImplementsInterface);
IMyService[] services = Composite.Manager.GetObjects<IMyService>();
该类将加载当前文件夹中的所有程序集，检查它们是否包含与输入参数匹配的类型。因为一旦加载一个程序集就不可能卸载，该类会将它们加载到不同的 AppDomain 中，这与单个程序集相反，可以删除。
为了在您的项目中使用它，您应该执行以下操作：
希望能帮助到你 ：）
我认为对于您的特殊情况，您也可以使用 MEF http://msdn.microsoft.com/en-us/library/dd460648.aspx