我很晚才回到这个需求，因为我们在 GAC 中有一些程序集，而 NHibernate 之类的东西需要解决它们。不是将所有这些qualifyAssembly 元素添加到每个app.config，下面的代码允许我们将它们添加到我们的machine.config。
using System;
using System.Collections.Generic;
using System.Configuration;
using System.IO;
using System.Reflection;
using System.Xml;
using System.Xml.XPath;
namespace MyNamespace {
/// <summary>
/// Implements <see cref="IDisposable"/> to provide a scope for resolving
/// assemblies described in the machine.config file with
/// <qualifyAssembly> elements.
/// </summary>
/// <remarks>
/// Because the framework only respects <qualifyAssembly> at the
/// application configuration level, this class provides similar
/// functionality for this element at the machine configuration level.
/// You can wrap a new instance of this class in a <b>using</b> statement
/// to get resolution within a specific scope; or, you can call the
/// <see cref="AssemblyResolver.Attach()"/> method to get
/// resolution for the lifetime of the current <see cref="AppDomain"/>.
/// </remarks>
public sealed class AssemblyResolver : IDisposable {
#region Private fields and implementation
private static Dictionary<string, string> _qualifiedNames;
private static Assembly ResolveAssembly(object sender, ResolveEventArgs args) {
if(_qualifiedNames == null) {
//
// Lazily initialize short/long name mappings.
//
_qualifiedNames = BuildQualifiedNameList();
}
if(!_qualifiedNames.ContainsKey(args.Name)) {
return null;
}
try {
return Assembly.Load(_qualifiedNames[args.Name]);
}
catch(FileNotFoundException) {
//
// TODO: Should this exception be propogated?
// It probably should not be hidden from the consumer
// since it likely indicates a configuration error.
//
return null;
}
}
private static Dictionary<string, string> BuildQualifiedNameList() {
var dict = new Dictionary<string, string>(StringComparer.InvariantCultureIgnoreCase);
//
// Get runtime XML data
//
var xml = GetConfigXml(GetMachineRuntimeSection());
if(xml == null) {
return dict;
}
//
// Iterate the qualifyAssembly elements and register in the list
//
var navigator = xml.CreateNavigator();
foreach(XPathNavigator qualifyAssembly in navigator.Select("runtime/asm:assemblyBinding/asm:qualifyAssembly", CreateNamespaceManager())) {
dict.Add(
qualifyAssembly.GetAttribute("partialName", string.Empty),
qualifyAssembly.GetAttribute("fullName", string.Empty));
}
return dict;
}
private static ConfigurationSection GetMachineRuntimeSection() {
System.Configuration.Configuration machineConfig = ConfigurationManager.OpenMachineConfiguration();
return machineConfig.GetSection("runtime") as ConfigurationSection;
}
private static IXPathNavigable GetConfigXml(ConfigurationSection runtimeSection) {
var ignoreSection = runtimeSection as IgnoreSection;
if(ignoreSection == null) {
return null;
}
//
// Cheat via Reflection to get the XML content of the config
// section.
//
FieldInfo field = typeof(IgnoreSection).GetField("_rawXml", BindingFlags.Instance | BindingFlags.NonPublic);
string rawXml = (string)field.GetValue(ignoreSection);
return new XPathDocument(new StringReader(rawXml));
}
private static IXmlNamespaceResolver CreateNamespaceManager() {
var nsmgr = new XmlNamespaceManager(new NameTable());
nsmgr.AddNamespace("asm", "urn:schemas-microsoft-com:asm.v1");
return nsmgr;
}
#endregion
/// <summary>
/// Creates a new <see cref="AssemblyResolver"/>.
/// </summary>
public AssemblyResolver() {
AppDomain.CurrentDomain.AssemblyResolve += new ResolveEventHandler(ResolveAssembly);
}
/// <summary>
/// Removes the current <see cref="AssemblyResolver"/>
/// from the <see cref="AppDomain"/>.
/// </summary>
public void Dispose() {
AppDomain.CurrentDomain.AssemblyResolve -= new ResolveEventHandler(ResolveAssembly);
GC.SuppressFinalize(this);
}
/// <summary>
/// Provides qualified assembly resolution for the lifetime of the
/// current <see cref="AppDomain"/>.
/// </summary>
public static void Attach() {
Attach(AppDomain.CurrentDomain);
}
/// <summary>
/// Provides qualified assembly resolution for the lifetime of an
/// <see cref="AppDomain"/>.
/// </summary>
/// <param name="appDomain">
/// The <see cref="AppDomain"/> to service.
/// </param>
public static void Attach(AppDomain appDomain) {
appDomain.AssemblyResolve += new ResolveEventHandler(ResolveAssembly);
}
}
}
在大多数情况下，我们通过像这样使用它来限制它的范围：
using(new AssemblyResolver()) {
//
// NHibernate initialization or whatever
//
}
它也可以在应用程序启动代码或 global.asax 中使用，并在应用程序的生命周期内持续存在，如下所示：
AssemblyResolver.Attach();
//
// or
//
AssemblyResolver.Attach(AppDomain.CurrentDomain);