所以我有一个接口(interface)叫做IWorkItem
在 WorkA
中实现, WorkB
和许多其他类。
public interface IWorker<T> where T : IWorkItem
{
void Process(T item);
}
IWorker<T>
接口(interface)在 WorkerA
中实现( IWorker<WorkA>
), WorkerB
( IWorker<WorkB>
) 和许多其他类。
public static void ProcessWorkItem(IWorkItem item)
{
(/* find the right worker */).Process(item);
}
现在我的问题是:如何找到能够处理给定 IWorkItem
的工作对象?
我的第一次尝试看起来像这样,但是泛型类型参数是个问题:
public static class WorkerRepository
{
private static Dictionary<Type, IWorker<???>> RegisteredWorkers =
new Dictionary<Type, IWorker<???>>();
public static void RegisterWorker(IWorker<???> worker)
{
var handled = from iface in worker.GetType().GetInterfaces()
where iface.IsGenericType
where iface.GetGenericTypeDefinition() == typeof(IWorker<>)
select iface.GetGenericArguments()[0];
foreach (var type in handled)
if (!RegisteredWorkers.ContainsKey(type))
RegisteredWorkers[type] = worker;
}
public static void ProcessWorkItem(IWorkItem item)
{
RegisteredWorkers[item.getType()].Process(item);
}
}
所以我有 Dictionary
包含 worker 。我在这里需要哪种类型的参数?在 Java 中我可以只使用 ? extends IWorkItem
,但我在 C# 中这样做吗?
然后是RegisterWorker
.您可能会为整个方法建议一个通用类型参数,例如 RegisterWorker<T>(IWorker<T> worker)
.但是,这也行不通,因为我想动态加载、实例化和注册 Workers。
这是正确的方法还是有更好的方法来实现这一点?
最佳答案
我做了一些更改,但得到了一个解决方案,您可以在其中保持通用性(而不是使用 object
s)。不确定您是否关心,但想将其添加为答案并让您决定。
我还写了一个测试来检查它是否真的有效,你应该可以复制/粘贴它。
[TestFixture]
public class WorkerThing
{
[Test]
public void RegisterAndRetrieveWorkers()
{
var repo = new WorkerRepository();
repo.RegisterWorker(new WorkerA());
var workerA = repo.RetrieveWorkerForWorkItem(new WorkItemA());
Assert.IsTrue(workerA is WorkerA);
repo.RegisterWorker(new WorkerB());
var workerB = repo.RetrieveWorkerForWorkItem(new WorkItemB());
Assert.IsTrue(workerB is WorkerB);
}
}
WorkerRepository
类。
public class WorkerRepository
{
private readonly Dictionary<Type, IWorker<IWorkItem>> _registeredWorkers =
new Dictionary<Type, IWorker<IWorkItem>>();
public void RegisterWorker(IWorker<IWorkItem> worker)
{
var type = (from iface in worker.GetType().GetInterfaces()
where iface.IsGenericType
where iface.GetGenericTypeDefinition() == typeof(IWorker<>)
select iface.GetGenericArguments()[0]).First();
if (!_registeredWorkers.ContainsKey(type))
{
_registeredWorkers[type] = worker;
}
}
// You don't need this method, just added it to check if I indeed retrieved the correct type
//
public IWorker<IWorkItem> RetrieveWorkerForWorkItem(IWorkItem item)
{
var type = item.GetType();
var registeredWorker = _registeredWorkers[type];
return registeredWorker;
}
public void ProcessWorkItem(IWorkItem item)
{
var type = item.GetType();
var registeredWorker = _registeredWorkers[type];
registeredWorker.Process(item);
}
}
工作项接口(interface)和类。
public interface IWorkItem
{
}
public class WorkItemA : IWorkItem
{
}
public class WorkItemB : IWorkItem
{
}
我在这里添加了 out
关键字以允许在界面上输入协方差。这样你就可以转换 WorkerA
至 IWorker<IWorkItem>
. (如单元测试示例中所示)
public interface IWorker<out T> where T : IWorkItem
{
void Process(IWorkItem workItem);
}
public class WorkerA : IWorker<WorkItemA>
{
public void Process(IWorkItem item)
{
}
}
public class WorkerB : IWorker<WorkItemB>
{
public void Process(IWorkItem item)
{
}
}
没有object
字典。没有反射。我希望这个例子有用!
干杯(感谢这个很酷的问题,它让我忙了一会儿:))
关于C#:持有一组处理程序对象并找到合适的对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15454591/