我最近将我正在处理的应用程序从Cocktail 1.4升级到Cocktail 2.6（Punch）。我已经为wpf项目调整了我的bootstrapper类，现在加载没有问题。但是，在我的WCF / Web项目中，我在尝试调用Composition.GetInstance时收到运行时异常并出现以下错误：
"You must first set a valid CompositionProvider by using Composition.SetProvider."
稍微深入研究一下这个问题后，当引导程序继承自CocktailMefBootstrapper时，会自动配置组合容器。我目前根本没有非wpf项目的bootstrapper类。在升级之前，我所要做的就是在Composition类上调用configure方法来配置组合容器，但它似乎已被弃用：
Composition.Configure();
我注意到你也可以调用Composition.SetProvider（），但我对如何完全满足方法签名有点不确定。 DevForce Punch documentation表示bootstrapper类的泛型类型应该是viewmodel，并且服务项目中没有视图/视图模型。这使我无法做什么，因为我不想从这些WCF项目中剔除鸡尾酒。在Cocktail（Punch）2.6项目中，是否还有一种方法可以使用Cocktail的合成容器而不使用自举程序？
更新
我找到了this on the DevForce forums。所以看来我应该学习如何配置多线程ICompositionProvider并调用如上所述的Composition.SetProvider（）。任何推荐的文章来实现这个目标？
答案 0 :(得分：1)
在深入了解Punch的源代码并查看实现ICompositionProvider的Ideablade的MefCompositionContainer后，我创建了自己的ICompositionProvider线程安全实现。以下是我使用的代码。基本上，它与Ideablade的MefCompositionContainer的代码相同，可以在in their repository找到。唯一的变化是我将一个true的bool标志传递给CompositionContainer的构造函数。 MSDN lists the pros and cons of making the container thread safe
internal partial class ThreadSafeCompositionProvider : ICompositionProvider
{
static ThreadSafeCompositionProvider()
{
CompositionHost.IgnorePatterns.Add("Caliburn.Micro*");
CompositionHost.IgnorePatterns.Add("Windows.UI.Interactivity*");
CompositionHost.IgnorePatterns.Add("Cocktail.Utils*");
CompositionHost.IgnorePatterns.Add("Cocktail.Compat*");
CompositionHost.IgnorePatterns.Add("Cocktail.dll");
CompositionHost.IgnorePatterns.Add("Cocktail.SL.dll");
CompositionHost.IgnorePatterns.Add("Cocktail.WinRT.dll");
}
public IEnumerable<Assembly> GetProbeAssemblies()
{
IEnumerable<Assembly> probeAssemblies = CompositionHost.Instance.ProbeAssemblies;
var t = GetType();
// Add Cocktail assembly
probeAssemblies = probeAssemblies.Concat(GetType().GetAssembly());
return probeAssemblies.Distinct(x => x);
}
private List<Assembly> _probeAssemblies;
private AggregateCatalog _defaultCatalog;
private ComposablePartCatalog _catalog;
private CompositionContainer _container;
public ComposablePartCatalog Catalog
{
get { return _catalog ?? DefaultCatalog; }
}
public ComposablePartCatalog DefaultCatalog
{
get
{
if (_defaultCatalog == null)
{
_probeAssemblies = GetProbeAssemblies().ToList();
var mainCatalog = new AggregateCatalog(_probeAssemblies.Select(x => new AssemblyCatalog(x)));
_defaultCatalog = new AggregateCatalog(mainCatalog);
CompositionHost.Recomposed += new EventHandler<RecomposedEventArgs>(OnRecomposed)
.MakeWeak(x => CompositionHost.Recomposed -= x);
}
return _defaultCatalog;
}
}
internal void OnRecomposed(object sender, RecomposedEventArgs args)
{
if (args.HasError) return;
var newAssemblies = GetProbeAssemblies()
.Where(x => !_probeAssemblies.Contains(x))
.ToList();
if (newAssemblies.Any())
{
var catalog = new AggregateCatalog(newAssemblies.Select(x => new AssemblyCatalog(x)));
_defaultCatalog.Catalogs.Add(catalog);
_probeAssemblies.AddRange(newAssemblies);
}
// Notify clients of the recomposition
var handlers = Recomposed;
if (handlers != null)
handlers(sender, args);
}
public CompositionContainer Container
{
get { return _container ?? (_container = new CompositionContainer(Catalog, true)); }
}
public Lazy<T> GetInstance<T>() where T : class
{
var exports = GetExportsCore(typeof(T), null).ToList();
if (!exports.Any())
throw new Exception(string.Format("Could Not Locate Any Instances Of Contract", typeof(T).FullName));
return new Lazy<T>(() => (T)exports.First().Value);
}
public T TryGetInstance<T>() where T : class
{
if (!IsTypeRegistered<T>())
return null;
return GetInstance<T>().Value;
}
public IEnumerable<T> GetInstances<T>() where T : class
{
var exports = GetExportsCore(typeof(T), null);
return exports.Select(x => (T)x.Value);
}
public Lazy<object> GetInstance(Type serviceType, string contractName)
{
var exports = GetExportsCore(serviceType, contractName).ToList();
if (!exports.Any())
throw new Exception(string.Format("Could Not Locate Any Instances Of Contract",
serviceType != null ? serviceType.ToString() : contractName));
return new Lazy<object>(() => exports.First().Value);
}
public object TryGetInstance(Type serviceType, string contractName)
{
var exports = GetExportsCore(serviceType, contractName).ToList();
if (!exports.Any())
return null;
return exports.First().Value;
}
public IEnumerable<object> GetInstances(Type serviceType, string contractName)
{
var exports = GetExportsCore(serviceType, contractName);
return exports.Select(x => x.Value);
}
public ICompositionFactory<T> GetInstanceFactory<T>() where T : class
{
var factory = new ThreadSafeCompositionFactory<T>();
Container.SatisfyImportsOnce(factory);
if (factory.ExportFactory == null)
throw new CompositionException(string.Format("No export found.", typeof(T)));
return factory;
}
public ICompositionFactory<T> TryGetInstanceFactory<T>() where T : class
{
var factory = new ThreadSafeCompositionFactory<T>();
Container.SatisfyImportsOnce(factory);
if (factory.ExportFactory == null)
return null;
return factory;
}
public void BuildUp(object instance)
{
// Skip if in design mode.
if (DesignTime.InDesignMode())
return;
Container.SatisfyImportsOnce(instance);
}
public bool IsRecomposing { get; internal set; }
public event EventHandler<RecomposedEventArgs> Recomposed;
internal bool IsTypeRegistered<T>() where T : class
{
return Container.GetExports<T>().Any();
}
public void Configure(CompositionBatch compositionBatch = null, ComposablePartCatalog catalog = null)
{
_catalog = catalog;
var batch = compositionBatch ?? new CompositionBatch();
if (!IsTypeRegistered<IEventAggregator>())
batch.AddExportedValue<IEventAggregator>(new EventAggregator());
Compose(batch);
}
public void Compose(CompositionBatch compositionBatch)
{
if (compositionBatch == null)
throw new ArgumentNullException("compositionBatch");
Container.Compose(compositionBatch);
}
private IEnumerable<Lazy<object>> GetExportsCore(Type serviceType, string key)
{
return Container.GetExports(serviceType, null, key);
}
}
在设置该类之后，我在启动期间添加了一个配置来实例化我的新线程安全组合提供程序并将其设置为Punch＆＃39的Composition类的提供程序：
if (createThreadSafeCompositionContainer)
{
var threadSafeContainer = new ThreadSafeCompositionProvider();
Composition.SetProvider(threadSafeContainer);
}
似乎像魅力一样工作！