我已经在MEF Codeplex论坛上提过这个问题,但是还没有得到回复,所以我想试试StackOverflow。如果有人感兴趣,这里是原帖的副本:
“首先,我完全是新手(今天才发现)MEF,并且迄今为止非常满意。然而,我遇到了一个非常令人沮丧的问题。我正在创建一个具有插件架构的应用程序,插件将仅存储在单个DLL文件中(或编码到主应用程序中)。DLL文件需要能够在运行时重新编译,应用程序应该识别此并重新加载插件(我知道这很困难,但这是一个要求)。为了实现这一点,我采取了这里介绍的方法(查找WebServerDirectoryCatalog)。基本上,想法是“监视插件文件夹,将新的/修改的程序集复制到Web应用程序的/bin文件夹中,并指示MEF从那里加载其导出内容。”这是我的代码,可能不是正确的方法,但这是我在网络上找到的一些示例:
main()...
string myExecName = Assembly.GetExecutingAssembly().Location;
string myPath = System.IO.Path.GetDirectoryName(myExecName);
catalog = new AggregateCatalog();
pluginCatalog = new MyDirectoryCatalog(myPath + @"/Plugins");
catalog.Catalogs.Add(pluginCatalog);
exportContainer = new CompositionContainer(catalog);
CompositionBatch compBatch = new CompositionBatch();
compBatch.AddPart(this);
compBatch.AddPart(catalog);
exportContainer.Compose(compBatch);
并且
private FileSystemWatcher fileSystemWatcher;
public DirectoryCatalog directoryCatalog;
private string path;
private string extension;
public MyDirectoryCatalog(string path)
{
Initialize(path, "*.dll", "*.dll");
}
private void Initialize(string path, string extension, string modulePattern)
{
this.path = path;
this.extension = extension;
fileSystemWatcher = new FileSystemWatcher(path, modulePattern);
fileSystemWatcher.Changed += new FileSystemEventHandler(fileSystemWatcher_Changed);
fileSystemWatcher.Created += new FileSystemEventHandler(fileSystemWatcher_Created);
fileSystemWatcher.Deleted += new FileSystemEventHandler(fileSystemWatcher_Deleted);
fileSystemWatcher.Renamed += new RenamedEventHandler(fileSystemWatcher_Renamed);
fileSystemWatcher.IncludeSubdirectories = false;
fileSystemWatcher.EnableRaisingEvents = true;
Refresh();
}
void fileSystemWatcher_Renamed(object sender, RenamedEventArgs e)
{
RemoveFromBin(e.OldName);
Refresh();
}
void fileSystemWatcher_Deleted(object sender, FileSystemEventArgs e)
{
RemoveFromBin(e.Name);
Refresh();
}
void fileSystemWatcher_Created(object sender, FileSystemEventArgs e)
{
Refresh();
}
void fileSystemWatcher_Changed(object sender, FileSystemEventArgs e)
{
Refresh();
}
private void Refresh()
{
// Determine /bin path
string binPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Plugins");
string newPath = "";
// Copy files to /bin
foreach (string file in Directory.GetFiles(path, extension, SearchOption.TopDirectoryOnly))
{
try
{
DirectoryInfo dInfo = new DirectoryInfo(binPath);
DirectoryInfo[] dirs = dInfo.GetDirectories();
int count = dirs.Count() + 1;
newPath = binPath + "/" + count;
DirectoryInfo dInfo2 = new DirectoryInfo(newPath);
if (!dInfo2.Exists)
dInfo2.Create();
File.Copy(file, System.IO.Path.Combine(newPath, System.IO.Path.GetFileName(file)), true);
}
catch
{
// Not that big deal... Blog readers will probably kill me for this bit of code :-)
}
}
// Create new directory catalog
directoryCatalog = new DirectoryCatalog(newPath, extension);
directoryCatalog.Refresh();
}
public override IQueryable<ComposablePartDefinition> Parts
{
get { return directoryCatalog.Parts; }
}
private void RemoveFromBin(string name)
{
string binPath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "");
File.Delete(Path.Combine(binPath, name));
}
所以所有这些实际上都起作用了,在main代码结束后,我的IEnumerable变量实际上已经填充了DLL中的所有插件(如果您遵循代码,则位于Plugins/1中,以便我可以修改插件文件夹中的dll)。现在,在这一点上,我应该能够重新编译插件DLL,将其放入Plugins文件夹中,我的FileWatcher检测到它已更改,然后将其复制到文件夹“2”中,directoryCatalog应该指向新文件夹。 所有这些都实际上都起作用了!问题是,即使似乎每件事情都指向了正确的位置,我的IEnumerable变量也从未更新为新的插件。离成功只差一步之遥!有什么建议吗? 我知道以这种方式做的不足之处,即没有任何DLL被卸载并导致内存泄漏,但它是一个Windows应用程序,可能每天至少启动一次,并且插件不太可能经常更改,但客户要求它在不重新加载应用程序的情况下执行此操作。 谢谢!感谢您提供的任何帮助,我因无法弄清楚而感到疯狂。
pluginCatalog.directoryCatalog
更改为新目录。它仍将监听旧目录的更改通知。对我而言,更改通知与您的问题非常相关;它怎么可能不是? - Wim Coenen