无法将源接口类型转换为目标接口类型

本文关键字：目标 接口类型 类型转换 接口 | 更新日期: 2023-09-27 18:27:42

我想处理保存在四个目录中的文件，它们的处理方式非常不同。

我有一个通用处理器IFileQueueService，它在调度计时器上运行，加载所有文件名，并为每个文件调用一个自定义处理器IExecutionProcessor。这可能是一个简单的问题，但我有比标准IExecutionProvider具有更多属性的处理器，我不知道如何调用这些自定义处理器。

//Basic processor interface
public interface IExecutionProvider
{
    void ProcessFile(string file);
}
//Simplified version of one of the custom processor interfaces
public interface IKyoExecutionProcessor
{
    string DestinationPath { get; set; }
}
public class KyoExecutionProcessor : IExecutionProvider, IKyoExecutionProcessor
{
   //This processor moves a file to the DestinationPath.
}
public interface IFileQueueService
{
    string SourcePath { get; set; }
    IExecutionProvider ExecutionProvider { get; set; }
    void Start();
    void Stop();
}
public class FileProcessor : IFileQueueService
{
    ...
    public virtual void ProcessFileQueue()
    {
        IEnumerable<string> filesToProcess = GetFilesReadyToProcess();
        foreach (string file in filesToProcess.ToList())
        {
            ExecutionProvider.ProcessFile(file);
        }
    }
}
public class KYOFileSysWatcher : ServiceBase
{
    private IFileQueueService Processor { get; set; }
    private IKyoExecutionProcessor KyoCustomProcessor { get; set; }
    public KYOFileSysWatcher()
    {
        Processor = ObjectFactory.GetInstance<IFileQueueService>();
        KyoCustomProcessor = ObjectFactory.GetInstance<IKyoExecutionProcessor>();
        //This doesn't work, cannot convert source type to target type, but it implements the IExecutionProvider interface??? How do I do this?
        Processor.ExecutionProvider = KyoCustomProcessor;
        Processor.Start(); //Sets up dispatch timer
    }
 }

无法将源接口类型转换为目标接口类型

救援通用。。。

//Basic processor interface
public interface IExecutionProvider
{
    void ProcessFile(string file);
}
//Simplified version of one of the custom processor interfaces
public interface IKyoExecutionProcessor
{
    string DestinationPath { get; set; }
}
public interface IFileQueueService<TProvider>
    where TProvider : IExecutionProvider
{
    string SourcePath { get; set; }
    TProvider ExecutionProvider { get; set; }
    void Start();
    void Stop();
}
public class FileProcessor<TProvider> : IFileQueueService<TProvider>
    where TProvider : IExecutionProvider
{
    string[] GetFilesReadyToProcess() { return new string[0]; }
    public TProvider ExecutionProvider { get; set; }
    public virtual void ProcessFileQueue()
    {
        IEnumerable<string> filesToProcess = GetFilesReadyToProcess();
        foreach (string file in filesToProcess.ToList())
        {
            ExecutionProvider.ProcessFile(file);
        }
    }
    #region IFileQueueService<TProvider> Members
    public string SourcePath { get; set; }
    public void Start() { }
    public void Stop() { }
    #endregion
}
public class KyoExecutionProcessor : IExecutionProvider, IKyoExecutionProcessor
{
    //This processor moves a file to the DestinationPath.
    public string DestinationPath { get; set; }
    public void ProcessFile(string file) { }
}
public class ServiceBase<TProcessor>
    where TProcessor : IExecutionProvider
{
    protected FileProcessor<TProcessor> Processor { get; set; }
    protected TProcessor CustomProcessor { get; set; }
}
public class KYOFileSysWatcher : ServiceBase<KyoExecutionProcessor>
{
    public KYOFileSysWatcher()
    {
        Processor = ObjectFactory.GetInstance<FileProcessor<KyoExecutionProcessor>>();
        CustomProcessor = ObjectFactory.GetInstance<KyoExecutionProcessor>();
        //This compiles now!
        Processor.ExecutionProvider = CustomProcessor;
        Processor.Start(); //Sets up dispatch timer
    }
}

您的IKyoExecutionProcessor接口应该从IExecutionProvider派生，如下所示：

public interface IKyoExecutionProcessor : IExecutionProvider 
{
    string DestinationPath { get; set; }
}

这确保了接口之间存在"is-a"关系，这也将使您能够实现KyoExecutionProcessor类，如下所示：

public class KyoExecutionProcessor : IKyoExecutionProcessor
{
   public void ProcessFile(string file) { ... }
   public string DestinationPath { get; set; }
}

这样，任何实现IKyoExecutionProcessor的对象都可以分配给IExecutionProvider类型的变量。

Processor.ExecutionProvider = KyoCustomProcessor; // You can now appoint IKyoExecutionProcessor instance to IExecutionProvider variable
相关文章：