.NET Remoting with Service 使用 DAAB 和 Unity 给出空引用异常

Question

我有一个使用 Unity 的项目，我正在尝试实现 NET Remoting。 我有一个用于现有服务层的 NET 远程服务器，该服务层具有使用企业库数据访问应用程序块的数据层。 问题是，由于调用 TestService 时 Remoting 需要无参数构造函数，所以我 得到一个空引用异常。 关于如何使用 Unity 实现这一点有什么想法吗？

这是我的代码：

来自服务层的 TestService：

public class TestService : MarshalByRefObject, ITestService
{
    private ITestRepository repository;

    public TestService(ITestRepository repository)
    {
        this.repository = repository;        
    }

    public TestService() <--- parameterless constructor
    {}

    public List<Book> GetBooks()
    {
        return repository.GetBooks();
    }

来自数据层的 TestRepository：

public class TestRepository : ITestRepository
{
    private Database db;

    public TestRepository(Database db)
    {
        this.db = db;      
    }

    public List<Book> GetBooks()
    {
      List<Book> list = new List<Book>();
        list.Add(new Book(1, "test book 1"));
        list.Add(new Book(2, "test book 2"));
        return list;
    }     

Book 类：

[Serializable]
public class Book : MarshalByRefObject
{
    public int ID { get; set; }
    public string Name { get; set; }

    public Book() { }
    public Book(int id, string name)
    {
        this.ID = id;
        this.Name = name;
    }
}

简单测试 RemotingServer：

TestRepository testRepository;
TestService testService;

IUnityContainer container = new UnityContainer();

container.AddNewExtension<EnterpriseLibraryCoreExtension>();
container.AddNewExtension<DataAccessBlockExtension>();


container.RegisterType<ITestRepository, TestRepository>();

container.RegisterType<ITestService, TestService>();

testService = container.Resolve<TestService>();

TcpServerChannel channel = new TcpServerChannel(9988);
ChannelServices.RegisterChannel(channel);
RemotingConfiguration.RegisterWellKnownServiceType(typeof(TestService), "TestService", WellKnownObjectMode.SingleCall);
System.Console.WriteLine("Press Any Key");
System.Console.ReadKey();

简单远程客户端：

ChannelServices.RegisterChannel(new TcpClientChannel());
ITestService testService = (ITestService)Activator.GetObject(typeof(ITestService), "tcp://localhost:9988/TestService");

foreach(Book item in testService.GetBooks())
{
  Console.WriteLine("Book:\n" + item.Name);    
}

Console.ReadKey();

这是完整的异常：

line 40 is calling repository.GetBooks();
at Test.Services.IssueService.GetBooks() in TestService.cs:line 40
at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs)
at System.Runtime.Remoting.Messaging.StackBuilderSink.PrivateProcessMessage(RuntimeMethodHandle md, Object[] args, Object server, Int32 methodPtr, Boolean fExecuteInContext, Object[]& outArgs)
at System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg, Int32 methodPtr, Boolean fExecuteInContext)